WMALT 2007-4

8/2/2019 WMALT 2007-4

1/394

B2 EDGAR HTML from 48648 1..119 ++

B5 1 c48648_424b5.htm

Prospectus Supplement to Prospectus Dated April 17, 2007

Washingt on Mut ual Mor tgage Pass-ThroughCert if icates, WMALT Series 2007-4

WaMu Asset Acceptance Corp.Depositor

Washington Mut ual Mort gage Securit ies Corp.Sponsor

Washington Mut ual Bank Servicer

$390,678,089(Approximate)

nsider carefully t he risk factors beginning on page S-14 in t his prospectus supplement and page 5 in t hecompanying prospectus.

e certificates will represent interests only in the issuing entity which is the Washington Mutual Mortgage Pass-Through Certificates WMALTies 2007-4 Trust and will not represent interests in or obligations of Washington Mutual Bank, Washington Mutual Mortgage Securitiesp., WaMu Asset Acceptance Corp., Washington Mutual, Inc. or any of their affiliates.

i ther these certificates nor the underlying mort gage loans are guaranteed by any agency or instrum entality of th e United States.

s prospectus supplement may be used to offer and sell the offered certificates only if accompanied by the prospectus.

Washington Mutual Mortgage Pass-Through Certificates WMALT Series 2007-4 Trust will issue twenty-four classes ofr ed certif icates and thr ee classes of priv ately placed cert ificat es. Each class of offered cert ificat es (other t han t he Class C-Certificates) w il l be entit led to receive monthly distribut ions of interest, principal or both, beginning on June 25, 2007.certificate int erest rate for some classes of offered certif icates wil l be variable. The table on page S-6 of thispectus supplement contains a l ist of the classes of offered certificates, including the initial class principal balance,ficate interest rate and special characteristics of each class.

primary asset of t he Trust w il l be a pool of first l ien single-family residential fix ed-rate mort gage loans. The Trust w il lcontain other assets, which are described on page S-30 of t his prospectus supplement.

red Certificates

l principal amount (approximate) $390,678,089

payment date

June 25, 2007

rest and/or principal paid Monthly

payment date June 25, 2037

it enhancement for the offered certificates is being provided by three classes of privately placed certificates, which have an aggregatecipal balance of approximately $3,546,029.

underwriter listed below will offer the offered certificates at varying prices to be determined at the time of sale. The proceeds to WaMut Acceptance Corp. from the sale of the offered certificates will be approximately 98.63% of the principal balance of the offered certificatesaccrued interest, before deducting expenses. The underwriters commission will be the difference between the price it pays to WaMut Acceptance Corp. for the offered certificates and the amount it receives from the sale of the offered certificates to the public.

her th e SEC nor any state securities commission has approved or disapproved of t he offered certificates or determ ined thatprospectus supplement or t he prospectus is accurate or complete. Any representation t o th e contrary is a crimin al offense.

Underwriter

WaMu Capit al Corp.May 23, 2007

ttp://www.sec.gov/Archives/edgar/data/1317069/000093041307004679/c48648_424b5.htm (1 of 395) [3/23/2012 4:54:36 PM]

8/2/2019 WMALT 2007-4

2/394


I mport ant Notice About Inf ormation Presented in thisProspectus Supplement and the Accompanying Prospectus

provide information to you about the offered certificates in two separate documents that progressively provide more detail: (a) thempanying prospectus, which provides general information, some of which may not apply to your series of certificates, and (b) thispectus supplement, which describes the specific terms of your series of certificates.

should be certain to review t he informat ion in this prospectus supplement for a description of t he specific terms of certif icates.

nclude cross-references in this prospectus supplement and the accompanying prospectus to captions in these materials where you canfurther related discussions. The following table of contents and the table of contents included in the accompanying prospectus provide thes on which these captions are located.

can find a listing of the pages where some of the capitalized terms used in this prospectus supplement and the accompanying prospectusdefined under the caption Index of Termson page S-117 in this prospectus supplement and under the caption Glossarybeginning on 143 in the accompanying prospectus. Capitalized terms used in this prospectus supplement and not otherwise defined in thispectus supplement have the meanings assigned in the accompanying prospectus.

European Economi c Area

lation to each Member State of the European Economic Area which has implemented the Prospectus Directive (each, a Relevant Membere), the Underwriter has represented and agreed that with effect from and including the date on which the Prospectus Directive is implementedat Relevant Member State (the Relevant Implementation Date) it has not made and will not make an offer of certificates to the public inRelevant Member State prior to the publication of a prospectus in relation to the certificates which has been approved by the competentority in that Relevant Member State or, where appropriate, approved in another Relevant Member State and notified to the competentority in that Relevant Member State, all in accordance with the Prospectus Directive, except that it may, with effect from and includingRelevant Implementation Date, make an offer of certificates to the public in that Relevant Member State at any time:

to legal entities which are authorized or regulated to operate in the financial markets or, if not so authorized or regulated, whose corporate purposeis solely to invest in securities;

to any legal entity which has two or more of (1) an average of at least 250 employees during the last financial year; (2) a total balance sheet ofmore than 43,000,000 and (3) an annual net turnover of more than 50,000,000, as shown in its last annual or consolidated accounts; or

in any other circumstances which do not require the publication by the issuer of a prospectus pursuant to Article 3 of the Prospectus Directive.

he purposes of this provision, the expression an offer of certificates to the public in relation to any certificates in any Relevant Membere means the communication in any form and by any means of sufficient information on the terms of the offer and the certificates to be offereds to enable an investor to decide to purchase or subscribe to the certificates, as the same may be varied in that Member State by anysure implementing the Prospectus Directive in that Member State and the expression Prospectus Directivemeans Directive 2003/71/ECncludes any relevant implementing measure in each Relevant Member State.

United Kingdom

underwriter has represented and agreed that:

it has only communicated or caused to be communicated and will only communicate or cause to be communicated an invitation or inducement toengage in investment activity (within the meaning of Section 21 of the Financial Services and Markets Act) received by it in connection with the issueor sale of the certificates in circumstances in which Section 21(1) of the Financial Services and Markets Act does not apply to the issuer; and

it has complied and will comply with all applicable provisions of the Financial Services and Markets Act with respect to anything done by it in relationto the certificates in, from or otherwise involving the United Kingdom.

S-2


8/2/2019 WMALT 2007-4

3/394


TABLE OF CONTENTS

Page

UMMARY INFORMATION S-5 Transaction Participants S-5 What You Own S-5

Information About the Mortgage Pool S-5 The Certificates S-6

The Offered Certificates S-6 The Exchangeable Offered Certificates

S-7 The Non-Offered Certificates S-7 Relationship Between Loan Groups, Subgroups and the

Offered Certificates S-8 Initial Principal Balance of the Certificates S-8 Last Scheduled Distribution Date S-8

Distributions on the Certificates S-8 Monthly Distributions S-8 Distributions of Interest S-9 Compensating Interest and Interest Shortfalls S-9 Distributions of Principal S-9 Cross-Collateralization S-11

Class R Certificates S-11 Credit Enhancements S-11

Allocation of Losses S-11 Optional Termination S-12

Yield Considerations S-12 Book-Entry Registration S-12 Denominations S-12 Legal Investment S-12 ERISA Considerations S-12 Federal Income Tax Consequences S-13 Ratings S-13

SK FACTORS S-14

HE SPONSOR S-25 General S-25 The Sponsors Origination Channels S-25

TATIC POOL INFORMATION S-26 NDERWRITING OF THE MORTGAGE LOANS S-26

General S-26 Evaluation of the Borrowers Credit Standing S-27 Evaluation of the Borrowers Repayment Ability S-27 Evaluation of the Adequacy of the Collateral S-27 Documentation Programs S-28 Exceptions to Program Parameters S-29

Automated Underwriting System

S-29 Due Diligence S-29 HE ORIGINATORS S-29

Washington Mutual Bank S-29 HE DEPOSITOR S-29 HE TRUST S-30

General S-30 Assignment of the Mortgage Loans and Other Assets to the

Trust S-30 Restrictions on Activities of the Trust S-31 Discretionary Activities With Respect to the Trust S-31

HE TRUSTEES S-32


8/2/2019 WMALT 2007-4

4/394


The Trustee S-32 General S-32 Material Duties of the Trustee S-32 Events of Default Under the Pooling Agreement S-33

The Delaware Trustee S-33 Limitations on the TrusteesLiability S-33 Resignation and Removal of the Trustees S-34

HE SERVICERS S-34 General S-34

The Servicer S-34 The Servicers Servicing Experience S-34 Servicing Procedures S-35 The Servicers Quality Control Procedures S-39

The Administrative Agent S-40 The Administrative Agents Servicing Experience S-40 Services Performed by the Administrative Agent S-40 The Administrative Agents Quality Control Procedures S-41

The Custodian S-41 Special Servicing Agreements S-42

FILIATIONS AND RELATED TRANSACTIONS S-42 ESCRIPTION OF THE MORTGAGE POOL S-43

Loan Group 1 S-44 Subgroup 1-1, Subgroup 1-2 and Subgroup 1-3 S-45

Loan Group 2 S-46 Additional Information S-46 Representations and Warranties Regarding the Mortgage Loans S-47 Criteria for Selection of Mortgage Loans S-48

ESCRIPTION OF THE CERTIFICATES S-49 General S-49 Book-Entry Registration S-51 Definitive Certificates S-51 Exchangeable Certificates S-52 Priority of Distributions

S-52 Distributions of Interest S-56 Distributions of Principal S-57

General S-57

S-3


8/2/2019 WMALT 2007-4

5/394


Page

Group 1 Certificate Principal Distributions S-58 Group 2 Certificate Principal Distributions S-62 Class C-P Certificate Principal Distributions S-63 Class B Certificate Principal Distributions S-63

Principal Prepayments S-65 Cross-Collateralization S-66 Subordination and Allocation of Losses S-67

Distributions to the Class C-PPP Certificates S-69 The Class R Certificates S-70

Available Distribution Amount S-71 Last Scheduled Distribution Date S-72 Optional Termination S-72

Amendment of the Pooling Agreement S-72 Payment of Fees and Expenses S-73 Reports and Other Information S-74

ELD AND PREPAYMENT CONSIDERATIONS S-76 General S-76 Principal Prepayments and Compensating Interest S-76 Lockout Certificates S-77 Rate of Payments S-77 Prepayment Assumptions S-77 Lack of Historical Prepayment Data S-79

Yield Considerations with Respect to the Class C-PPP

Certificates S-80 Yield Considerations with Respect to the Interest Only and

Principal Only Certificates S-80 Yield Considerations with Respect to the Senior Subordinate

Certificates S-81 Additional Yield Considerations Applicable Solely to the Class R

Certificates S-84 REDIT ENHANCEMENTS S-84

Subordination

S-84 Shifting of Interests S-85 ATERIAL FEDERAL INCOME TAX CONSEQUENCES S-85

Taxation of Owners of the Class PPP Certificates S-86 Special Tax Considerations Applicable to the Exchangeable

Certificates S-87 Special Tax Considerations Applicable to the Residual

Certificates S-89 ERTAIN LEGAL INVESTMENT ASPECTS S-91 RISA CONSIDERATIONS S-92 ETHOD OF DISTRIBUTION S-93 GAL MATTERS S-94

ERTIFICATE RATINGS S-94 PENDIX A: DECREMENT TABLES S-95 PENDIX B: MORTGAGE LOAN TABLES S-99 PENDIX C: AVAILABLE EXCHANGES OF EXCHANGEABLE

ERTIFICATES S-114 DEX OF TERMS S-117

S-4


8/2/2019 WMALT 2007-4

6/394


SUMMARY I NFORMATI ON

following summarylights selected informationthis prospectus supplement.es not contain all ofnformation that you need

onsider in making yourstment decision. To understandterms of the offeredficates, read carefullyentire prospectus supplementthe accompanying prospectus.

summary provides an overviewertain calculations, cashs and other information toyour understanding. Thismary is qualified by thedescription ofe calculations, cash flowsother information inprospectus supplement andaccompanying prospectus.

NSACTI ON PARTI CIPANTS

May 25, 2007, which is the closing date, the mortgage loans that support the certificates will be sold by Washington Mutual Mortgagerities Corp., the sponsor of the securitization transaction, to WaMu Asset Acceptance Corp., the depositor. On the closing date, the depositorell the mortgage loans and related assets to the Washington Mutual Mortgage Pass-Through Certificates WMALT Series 2007-4 Trust.

xchange for the mortgage loans and related assets, the Trust will issue the certificates pursuant to the order of the depositor.sponsor purchased all of the mortgage loans from Washington Mutual Bank, which originated all of the mortgage loans.

mortgage loans will be serviced by Washington Mutual Bank, as servicer. Some servicing activities will be performed by Washingtonual Mortgage Securities Corp., as administrative agent of the servicer. Some servicing activities will be outsourced to third party vendors.

trustee of the Trust will be LaSalle Bank National Association, and the Delaware trustee will be Christiana Bank & Trust Company.hington Mutual Bank fsb will have possession of and will review the mortgage notes, mortgages and other legal documents related tomortgage loans as custodian for the Trust.

AT YOU OWN

r certificates represent interests only in the assets of th e issuing entit y. All payments to you w ill come only fromamount s received in connection wit h th ose assets.

Trust owns a pool of fixed-rate mortgage loans and certain other assets, as described under The Trust in this prospectus supplement.

e are no outstanding series or classes of securities that are backed by the assets of the issuing entity or otherwise have claims on the assetse issuing entity, other than the certificates. The depositor does not expect that any securities representing additional interests in or claims on

assets of the issuing entity will be issued in the future.

rmat ion About t he Mortgage Pool

mortgage pool consists of 662 mortgage loans with an aggregate principal balance as of May 1, 2007 of approximately $394,224,019. All ofmortgage loans are secured by residential properties or shares of cooperative apartments, and each is set to mature within 30 years of the dates originated.

e event of a material breach of the representations and warranties made by the sponsor or the depositor with respect to the mortgage loans,the event that a required loan document is not included in the mortgage files for the mortgage loans, the breaching party will, unless it

cured the breach in all material respects, be required to repurchase the affected mortgage loan or substitute a new mortgage loan foraffected mortgage loan. See Description ofMortgage Pool RepresentationsWarranties Regarding thegage Loans in thispectus supplement .

mortgage pool consists of the following two loan groups:

Loan Group

Number ofMortgage

Loans

ApproximatePrincipal Balance

as ofMay 1, 2007

MaximumYears toMaturity

FromOrigination

Date

n Group 1 610 $

363,833,526 30

n Group 2 52 $

30,390,492 15

group 1 will be further subdivided into three subgroups as more fully explained in this prospectus supplement. Forrther description of thetgage loans in each loan groupeach subgroup, see Descriptione Mortgage Pool and Appendixthis prospectus supplement.

S-5


8/2/2019 WMALT 2007-4

7/394



8/2/2019 WMALT 2007-4

8/394


CERTIFI CATES

Offer ed Certi ficat es

approximate initial class principal balance, annual certificate interest rate and type of each class of the offered certificates will be as follows:

Class

ApproximateI nitial Class

PrincipalBalance

AnnualCertificate

I nterest Rate Type-1 $

91,435,000 (1)

5.500% Senior/Exchangeab

-2 5,475,500 5.500% Senior/Mezzanine

-3

180,842,600 (2)

6.000%

Senior/Exchangeab

-4 10,829,500 (2)

6.000% Senior/Exchangeabl

Mezzanine

-5 52,998,400 7.000% Senior


-7 9,143,500 (1)

5.500% Senior/Exchangeabl

Lockout

-8 82,291,500 (1)


-9 70,622,300 (1)


-10 11,669,200 (1)


-11 75,895,400 (1)


-12 6,396,100 (1)


-13 191,672,100 (2)

6.000% Senior/Exchangeab-1 8,543,400 (3)


-2 18,467,000 (3)



-4 27,010,400 (3)


7.000%(4) Senior/Interest Onl

242,289 (5) Senior/Principal Onl

8,874,700 Variable(6) Subordinate



100 5.500% Senior/Residual

PP 100 (7) Prepayment Penalty

The Class 1-A-1, Class 1-A-7, Class 1-A-8, Class 1-A-9, Class 1-A-10, Class 1-A-11 and Class 1-A-12 Certificates are referred to in this prospectussupplement as the subgroup 1-1 exchangeable certificates, and, in certain combinations, may be exchanged for certain other subgroup 1-1exchangeable certificates as described below in The Exchangeable Offered Certificatesand in Appendix C. For these certificates, the principalbalance listed in this chart represents the maximum initial class principal balance. On the closing date, each of these certificates will have an initialclass principal balance up to its maximum initial class principal balance such that the total initial class principal balance of these certificates willequal $91,435,000.

The Class 1-A-3, Class 1-A-4 and Class 1-A-13 Certificates are referred to in this prospectus supplement as the subgroup 1-2 exchangeablecertificates, and, in certain combinations, may be exchanged for certain other subgroup 1-2 exchangeable certificates as described below in TheExchangeable Offered Certificatesand in Appendix C. For these certificates, the principal balance listed in this chart represents the maximum initialclass principal balance. On the closing date, each of these certificates will have an initial class principal balance up to its maximum initial classprincipal balance such that the total initial class principal balance of these certificates will equal $191,672,100.

The Class 2-A-1, Class 2-A-2 and Class 2-A-4 Certificates are referred to in this prospectus supplement as the group 2 exchangeable certificates,and, in certain combinations, may be exchanged for certain other group 2 exchangeable certificates as described below in The ExchangeableOffered Certificatesand in Appendix C. For these certificates, the principal balance listed in this chart represents the maximum initial class principal

balance. On the closing date, each of these certificates will have an initial class principal balance up to its maximum initial class principal balancesuch that the total initial class principal balance of these certificates will equal $27,010,400.

The Class C-X Certificates will not receive any distributions of principal, but will accrue interest on the Class C-X notional amount. The initial Class C-X notional amount will be approximately $2,132,648. See Description of theCertificates Distributions of Interest in this prospectus supplement .

These certificates will not receive any distributions of interest.

The initial certificate interest rate on the Class B-1, Class B-2 and Class B-3 Certificates will each be approximately 5.990% per annum and will varyafter the first distribution date between 5.500% and 7.000% per annum. For a more detailed description of the certificate interest rate on thesecertificates, see Description of theCertificates Distributions of Interest Class B Certificate Interest Rate inthis prospectus supplement.


8/2/2019 WMALT 2007-4

9/394


The Class C-PPP Certificates will receive $100 of principal on the distribution date in May 2011 from the Class C-PPP Reserve Fund. The Class C-PPPCertificates will not receive any distributions of interest, nor will they receive distributions of principal on any other distribution date. The Class C-PPP Certificates will also have a notional balance, the Class C-PPP Notional Amount,which will equal approximately $394,224,019, theaggregate principal balance of the mortgage loans as of May 1, 2007. The Class C-PPP Certificates will

S-6


8/2/2019 WMALT 2007-4

10/394


be entitled to receive prepayment penalties paid by borrowers upon voluntary full prepayment of certain mortgage loans if those mortgage loansare prepaid during certain periods. Accordingly, these amounts will not be available for distribution to other classes of certificates.See Description of the MortgagePool, Description of theCertificates Distributions to theClass C-PPP Certificates and the Prepayment Penalty Amount and Term tables in Appendix B in thisprospectus supplement for moreinformation regarding the Class C-PPPCertificates and prepayment penalties.

Exchangeabl e Offered Certi ficates

group 1-1angeable Certificates. The Class 1-A-1, Class 1-A-7, Class 1-A-8,s 1-A-9, Class 1-A-10, Class 1-A-11 and Class 1-A-12 Certificates are referred to in this prospectus supplement as the subgroup 1-1angeable certificates. Holders of the subgroup 1-1 exchangeable certificates will be entitled to exchange all or a portion of those certificatesertain proportions of other of these subgroup 1-1 exchangeable certificates. Together, the subgroup 1-1 exchangeable certificates haveggregate initial class principal balance of $91,435,000. On each distribution date, these certificates will, in the aggregate, receive an interestof 5.500% on their aggregate class principal balance outstanding at such time. See Appendixr a description of thet available exchanges. See

Description of the CertificatesExchangeable Certificates inprospectus supplement.

group 1-2

angeable Certificates. The Class 1-A-3, Class 1-A-4 and Class 1-A-ertificates are referred to in this prospectus supplement as the subgroup 1-2 exchangeable certificates. Holders of the subgroup 1-changeable certificates will be entitled to exchange all or a portion of those certificates for certain proportions of other of these subgroup 1-changeable certificates. Together, the subgroup 1-2 exchangeable certificates have an aggregate initial class principal balance of,672,100. On each distribution date, these certificates will, in the aggregate, receive an interest rate of 6.000% on their aggregate class

cipal balance outstanding at such time. See Appendix C forscription of the exactable exchanges. See


up 2 Exchangeable Certificates. The Class 2-A-ass 2-A-2 and Class 2-A-4 Certificates are referred to in this prospectus supplement as the group 2 exchangeable certificates. Holders ofgroup 2 exchangeable certificates will be entitled to exchange all or a portion of those certificates for certain proportions of other of these groupchangeable certificates. Together, the group 2 exchangeable certificates have an aggregate initial class principal balance of $27,010,400. Ondistribution date, these certificates will, in the aggregate, receive an interest rate of 5.500% on their aggregate class principal

nce outstanding at such time. See Appendix C forscription of the exactable exchanges. See


Non-Offered Certificates

ddition to the offered certificates, the Trust will also issue the Class B-4, Class B-5 and Class B-6 Certificates. These certif icates are notg offered by t his prospectus supplement.

approximate initial class principal balance, annual certificate interest rate and type of each of the Class B-4, Class B-5 and Class B-6ficates will be as follows:

Class

Approximate

I nitial ClassPrincipalBalance

Annual

CertificateInterest

Rate Type

$

1,576,000 Variable (1) Subordinate 1,182,000 Variable (1) Subordinate 788,029 Variable (1) Subordinate

The initial certificate interest rate on the Class B-4, Class B-5 and Class B-6 Certificates will each be approximately 5.990% per annum and willvary after the first distribution date between 5.500% and 7.000% per annum. For a more detailed description of the certificate interest rate onthese certificates, see Description of theCertificates Distributions of Interest Class B Certificate Interest Rate in this prospectus supplement.

Class B-4, Class B-5 and Class B-6 Certificates will be subordinate in right of payment to the offered certificates and will not receive


8/2/2019 WMALT 2007-4

11/394


butions of interest or principal on any distribution date until the offered certificates have received all distributions of interest and principalthey are entitled to receive on that distribution date. In addition, losses realized on the mortgage loans will be allocated to the Class B-4,s B-5 and Class B-6 Certificates, until their principal balances have been reduced to

S-7


8/2/2019 WMALT 2007-4

12/394


before they are allocated to the offered certificates. See Description ofCertificates SubordinationAllocation of Losses inprospectus supplement.

ationship Between Loan Groups, Subgroups and the Offered Certificates

certificates whose class designation begins with 1 correspond to loan group 1.

ddition, the Class 1-A-1, Class 1-A-2, Class 1-A-7, Class 1-A-8, Class 1-A-9, Class 1-A-10, Class 1-A-11 and Class 1-A-12 Certificates correspondbgroup 1-1, the Class 1-A-3, Class 1-A-4 and Class 1-A-13 Certificates correspond to subgroup 1-2 and the Class 1-A-5 and Class 1-A-rtificates correspond to subgroup 1-3.

certificates whose class designation begins with2

correspond to loan group 2.Class C-X, Class C-P and Class C-PPP Certificates and the subordinate certificates, whose class designation begins with B, correspond togroup 1 and loan group 2.

of the certificates generally receives distributions based on principal and interest collected from mortgage loans in its corresponding loanp, subgroup, or loan groups.

al Principal Balance of t he Certif icates

nitial aggregate principal balance of the certificates issued by the Trust is approximately $394,224,118, subject to an upward ornward variance of no more than 5%.

nitial aggregate principal balance of the certificates has the following composition:

e senior certificates in the aggregate comprise approximately 95.65% of the aggregate principal balance of both loan groups;

e Class B-1, Class B-2 and Class B-3 Certificates comprise approximately 3.45% of the aggregate principal balance of both loan groups; and

e privately placed Class B-4, Class B-5 and Class B-6 Certificates comprise approximately90% of the aggregate principal balance of both loan groups.

Scheduled Distribution Date

ast scheduled distribution date for each class of certificates is the distribution date in the month after the scheduled maturity date for thet maturing mortgage loan in the related loan group or loan groups; provided, however, the last scheduled distribution date for the Class C-PPP Certificates will be the distribution date in May 2011.

actual rate of principal payments on the certificates will depend on the rate of principal payments (including principal prepayments) on theed mortgage loans. No assurance can be given as to the actual payment experience on the mortgage loans.

Description of the Certificatesast Scheduled Distribution Date is prospectus supplement.

TRI BUTIONS ON THE CERTI FI CATES

thly Distributions

month, the trustee, LaSalle Bank National Association, will make distributions of interest and/or principal to the holders of theficates. Distributions will be made on the 25th day of each month, or if the 25th day is not a business day, on the next business day. Thedistribution date will be June 25, 2007.

rce of Payments. The mortgagors pay their interest and principal during the month toervicer. Each month, the servicer subtracts its servicing fee, and sends the remainder to the trustee. On the distribution date for that month,rustee distributes that remaining amount by loan group to the holders of the certificates related to that loan group in the order describedescription of the CertificatesPriority of Distributions in this prospectus supplement (in accordance with the monthly distribution report).servicing fee will be calculated as a per annum percentage for each mortgage loan. The servicing fee for each group 1 loan will range0.250% to 0.500%, with a weighted average of approximately 0.470%. The servicing fee for each group 2 loan will range from 0.250%

500%, with a weighted average of approximately 0.429%.

ances. For any month, if the servicer receives a payment on a mortgage loan that is less than the full scheduledment or if no payment is received at all, the servicer will advance funds held by the servicer for future distribution, or its own funds, to covershortfall. However, the servicer will not

S-8


8/2/2019 WMALT 2007-4

13/394


equired to make advances if it determines that those advances will not be recoverable from future payments or collections on that mortgageSee The Servicers The Servicer

Servicing Procedures Advances inprospectus supplement.

ributions of Interest

class of offered certificates entitled to interest will accrue interest each month. On each distribution date interest will be distributed toe classes of certificates in the order described in Description of the CertificatesPriority of Distributions in this prospectus supplement.

possible that, on any given distribution date, there will be insufficient payments from the mortgage loans to make the interestbutions contemplated in this prospectus supplement. If the servicer does not advance its own funds, because it determines that thence would be nonrecoverable, some certificates, most likely the subordinate certificates, may not receive the full amount of accrued interest

hich they are entitled. If this happens, those certificates will be entitled to receive any shortfall in interest distributions on future distributions in the same priority as their distribution of current interest. However, there will be no extra interest paid to make up for the delay.

amount of interest each class of certificates accrues each month will generally equal 1/12th of the annual interest rate for that class multipliedhe related class principal balance or class notional amount, as applicable. The principal balance or notional amount used for this calculation onirst distribution date will be the applicable balance as of May 25, 2007, which is the closing date. The principal balance or notional amountfor this calculation on any other distribution date will be the applicable balance immediately after the preceding distribution date. The

ual interest rate for each class of offered certificates entitled to interest is described on pages S-6 and S-7 of this prospectus supplement. Forscription of how the notional amounts are determined, see Descriptione Certificates Distributionsterest in thispectus supplement.

Class C-P and Class C-PPP Certificates will not receive any distributions of interest.

pensating In terest and Int erest Shortf alls

ayments in Full. When mortgagors make prepayments in full, they need not pay a

months interest. Instead, they are required to pay interest only to the date of their prepayment. To partially compensate certificateholders forhortfall in interest this causes, the servicer may pay compensating interest to the certificateholders out of the servicing fee it collects, as wellom certain other sources. For a description of how compensating interest payable by the servicer is calculated, and how it is allocated amongertificates, as well as important limitations on the amount of compensating interest,

Description of the CertificatesDistributions of Interest pensating Interest and YieldPrepayment Considerations inprospectus supplement.

al Prepayments. When mortgagors make partial prepayments, they do not pay interesthe amount of that prepayment. Certificateholders will receive no compensating interest to compensate them for the shortfall in interestcauses.

ribu tions of Principal

eral. As the mortgagors pay principal on the mortgage loans in each loan group, that principal is passed on to

holders of certificates related to that loan group. However, not every class of certificates w il l receive principal on eachribution date.

groups. For the purposes of distributions to the senior certificates related to loan group 1, the mortgage loans ingroup 1 will be divided into three separate subgroups. As the mortgagors pay principal on the mortgage loans (or portions of mortgage loans)ch subgroup of loan group 1, that principal is passed on to the holders of certificates related to that subgroup.

cipal payments relating to the mortgage loans (or portions of mortgage loans) in subgroup 1-1 will be used to pay the Class 1-A-1, Class 1-A-ass 1-A-7, Class 1-A-8, Class 1-A-9, Class 1-A-10, Class 1-A-11 and Class 1-A-12 Certificates as well as the group 1 portion of the Class C-rtificates. Principal payments relating to the mortgage loans (or portions of mortgage loans) in subgroup 1-2 will be used to pay the Class 1-A-ass 1-A-4 and Class 1-A-13 Certificates. Principal payments relating to the mortgage loans (or portions of mortgage loans) in subgroup 1-3 willsed to pay the Class 1-A-5 and Class 1-A-6 Certificates. However, in certain

S-9


8/2/2019 WMALT 2007-4

14/394


mstances, payments from mortgage loans in one loan group or subgroup may be used to pay principal to the certificates related to the othergroup or subgroup, as described in Description of the CertificatesCross-Collateralization in this prospectus supplement.

Description of the Mortgage Pooloan Group 1 Subgroup 1-1, Subgroupand Subgroup 1-3

Description of the CertificatesDistributions of Principal inprospectus supplement fortailed description of, forgroup 1, which mortgage loans,

ortions of mortgage loans,ng to which subgroup.

s C-P Certificates. On each distribution date, the Class C-P Certificateseceive a portion of the principal received or advanced on each discount mortgage loan. A discount mortgage loan is a mortgage loan withnnual interest rate, after subtracting the servicing fee, of less than 5.500%. For a description of the principal distributions to the Class C-rtificates, see Description ofCertificates Distributionsrincipal in thispectus supplement.

group 1-1 Certificates. On each distribution date, a portion ofprincipal received or advanced on the group 1 loans (or portions of those mortgage loans) in subgroup 1-1 will be distributed to the Class 1-A-ass 1-A-2, Class 1-A-7, Class 1-A-8, Class 1-A-9, Class 1-A-10, Class 1-A-11 and Class 1-A-12 Certificates in the order of priority describedescription of the CertificatesDistributions of PrincipalGroup 1 Certificate Principal DistributionsSubgroup 1-1 Certificate PrincipalibutionsSubgroup 1-1 Senior

cipal Distribution Amount in this prospectuslement. However, not all of t hese certificates wil l receive principal on each distribut ion date. See Appendix A for a t able

wing, for each class of certificates entitled to pr incipal, the expected rate of retu rn of pr incipal at different rates of

payments on the mor tgage loans in subgroup 1-1. However, if there are no subordinate certificates outstanding, the Class 1-A-1, Class 1-Class 1-A-7, Class 1-A-8, Class 1-A-9, Class 1-A-10, Class 1-A-11 and Class 1-A-12 Certificates will not receive principal in the order ofity described in Description of the CertificatesDistributions of PrincipalGroup 1 Certificate Principal DistributionsSubgroup 1-1ficate Principal DistributionsSubgroup 1-1 Senior

cipal Distribution Amount in this prospectus supplement.ead, each of these classes of certificates will generally receive principal pro rata according to its class principal balance.

group 1-2 Certificates. On each distribution date, a portion ofprincipal received or advanced on the group 1 loans (or portions of those mortgage loans) in subgroup 1-2 will be distributed, pro rata, toClass 1-A-3, Class 1-A-4 and Class 1-A-13 Certificates. See Description ofCertificates Distributionsrincipal Group 1ificate Principal Distributions

Subgroup 1-2 Certificatecipal Distributions Subgroup 1-nior Principal Distributionunt in this prospectus supplement.

group 1-3 Certificates. On each distribution date, a portion ofprincipal received or advanced on the group 1 loans (or portions of those mortgage loans) in subgroup 1-3 will be distributed, pro rata, toClass 1-A-5 and Class 1-A-6 Certificates. See Description ofCertificates Distributionsrincipal Group 1ificate Principal Distributions

Subgroup 1-3 Certificatecipal Distributions Subgroup 1-nior Principal Distributionunt in this prospectus supplement.

up 2-A Certificates. On each distribution date, a portion of thecipal received or advanced on all of the group 2 loans will be distributed to the Class 2-A-1, Class 2-A-2, Class 2-A-3 and Class 2-A-4ficates entitled to receive principal in the order of priority described in Description of the CertificatesDistributions of PrincipalGrouprtificate Principal DistributionsGroup 2 Seniorcipal Distribution Amount in this prospectuslement. However, not all of t hese certificates wil l receive principal on each distribut ion date. See Appendix A for a t able

wing, for each class of certificates entitled to pr incipal, the expected rate of retu rn of pr incipal at different rates ofpayments on the mor tgage loans in loan group 2. However, if there are no subordinate certificates outstanding, the Class 2-A-1, Class 2-Class 2-A-3 and Class 2-A-4 Certificates entitled to receive principal will not receive principal in the order of priority described in Descriptione CertificatesDistributions of PrincipalGroup 2 Certificate Principal DistributionsGroup 2or Principal Distribution Amount inprospectus supplement. Instead, each of these classes of certificates will generally receive principal pro rata according to its classcipal balance.

s B Certificates. On each distribution date, the Class B-1, Class B-2, Class B-ass B-4, Class B-5 and Class B-6 Certificates will be entitled to receive a portion of the principal received or

S-10


8/2/2019 WMALT 2007-4

15/394


nced on all of the mortgage loans, pro rata, according to their respective class principal balances. However, under certain conditions describeds prospectus supplement under Description of the CertificatesPriority of Distributions, the amount of principal prepaymentsrwise distributable to some classes of these Class B Certificates will instead be paid to other classes of these certificates with a higher priority.

rity of Principal Distributions. Each classrtificates in a certificate group receives its principal entitlements in the order described in Description of the CertificatesPrioritystributions in this prospectus supplement. It is possible that, on any given distribution date, there will be insufficient payments from

mortgage loans to make principal distributions as contemplated in this prospectus supplement. As a result, some certificates, most likelyubordinate certificates, may not receive the full amount of principal distributions to which they are entitled.

Class C-X and Class C-PPP Certificates will not receive any distributions of principal (except for a distribution of $100 to the Class C-Certificates on the distribution date in May 2011).

a more detailed description of how distributions of principal will be allocated among the various classes of certificates, Description of the Certificates

Distributions of Principal inprospectus supplement.

ss-Collateralization

ertain limited circumstances, principal and interest collected from one or more of subgroup 1-1, subgroup 1-2, subgroup 1-3 or loan group 2be used to pay principal or interest, or both, to the senior certificates unrelated to that loan group or subgroup.

Description of the CertificatesCross-Collateralization inprospectus supplement .

Class R Certificates

Class R Certificates will receive $100 of principal on the first distribution date, as well as one months interest on that amount. Theseficates are not expected to receive any material distributions on any other distribution date.

Description of the CertificatesThe Class R Certificates inprospectus supplement. However, holders of the Class Rficates may have tax liabilities that substantially exceed any distributions on those certificates. See

Yield and Prepayment Considerationsdditional Yieldsiderations Applicable Solelye Class R Certificates

Material Federal IncomeConsequences SpecialConsiderations Applicable toResidual Certificates inprospectus supplement.

DI T ENHANCEMENTS

ordination . The senior certificates will receive all distributions of interest and principal that they are entitled

ceive on each distribution date before the subordinate certificates receive any distributions on that distribution date. This providest enhancement to the senior certificates. In a similar fashion, each class of subordinate certificates will provide credit enhancement to allr subordinate certificates with lower numerical class designations.

ing of Interests . The senior certificates entitled to distributions of principal inaggregate will receive 100% of principal prepayments received on the mortgage loans in the related loan group (or subgroup) until theanniversary of the first distribution date. During the next four years, those senior certificates in the aggregate will generally receiveproportionately large, but decreasing, share of these principal prepayments. This will result in a quicker return of principal to thoseor certificates and increases the likelihood that holders of those senior certificates will be paid the full amount of principal to which theyentitled. For a more detailed description of how principal prepayments are allocated among the senior certificates and therdinate certificates, see Description of

Certificates Principalayments in thispectus supplement.

OCATI ON OF LOSSES

ized Losses . A loss is realized on a mortgage loan when the servicer determines that it has receivedmounts it expects to recover for that mortgage loan and the amounts are less than the outstanding principal balance of the mortgage loan andccrued and unpaid interest. Losses wil l be allocated t o th e certificates by deducting t he losses from t he principal balance ofcertificates without making any payments to th e certif icateholders. In general, the amount of losses will be allocated to the mostr class of subordinate certificates then outstanding. In general, losses will be allocated to the senior certificates

S-11


8/2/2019 WMALT 2007-4

16/394


after the principal balances of all of the subordinate certificates have been reduced to zero.

es on Discount Mortgage Loans. Losses realized ondiscount mortgage loans will be treated differently from other losses. A portion of the loss on each discount mortgage loan will first be allocatede Class C-P Certificates, and the remainder of the loss will be allocated in the usual manner. However, the portion of the loss allocated to

Class C-P Certificates will usually be recovered by those certificates through amounts otherwise allocable to the subordinate certificatesescribed in Description of the CertificatesPriority of Distributions in this prospectus supplement, and the amounts so recovered willlocated as a loss to the most junior class of subordinate certificates then outstanding.

a more detailed description of the allocation of realized losses among the certificates, Description of the Certificates

Subordination and Allocation

osses

in thispectus supplement.

I ONAL TERMI NATION

n the aggregate principal balance of the mortgage loans has been reduced to less than 10% of that balance as of May 1, 2007, the servicerpurchase all of the mortgage loans, which will cause the retirement of the certificates.

Description of the CertificatesOptional Termination inprospectus supplement.

LD CONSI DERATI ONS

yield to maturity of each class of certificates will depend upon, among other things:

e price at which the certificates are purchased;

e applicable certificate interest rate, if any;

hether an optional termination occurs; and

e rate of prepayments (including liquidations) on the related mortgage loans;

Yield andayment Considerations inprospectus supplement.

certificates that receive only distributions of principal or only distributions of interest will be especially sensitive to the rate of prepayments. Forcussion of special yield considerations applicable to these classes of certificates, see

Risk Factors and YieldPrepayment Considerations d Considerations with Respecte Interest Only and

cipal Only Certificates inprospectus supplement.

OK-ENTRY REGI STRATIONeneral, the offered certificates, other than the Class R Certificates, will be available only in book-entry form through the facilities of Theository Trust Company, Euroclear and Clearstream. See Description ofSecurities Form of Securities e accompanying prospectus .

OMI NATIONS

offered certificates, other than the Class 1-A-10, Class 1-A-12, Class 2-A-2, Class C-X, Class C-PPP and Class R Certificates, are offerednimum denominations of $25,000 initial class principal balance each and multiples of $1 in excess of $25,000.

Class C-X Certificates are offered in minimum denominations of $100,000 initial Class notional amount each and multiples of $1 in excess00,000.

Class 1-A-10, Class 1-A-12 and Class 2-A-2 Certificates are offered in minimum denominations of $1,000 initial class principal balance eachmultiples of $1 in excess of $1,000.

Class C-PPP Certificates will be offered in minimum denominations of $200,000,000 initial class notional amount each and multiples of $1

cess of $200,000,000.Class R Certificates will have an initial class principal balance of $100 and will be offered in a single certificate that represents a 99.99%est in its class.

AL I NVESTMENT

f the date of their issuance, all of the offered certificates, other than the Class B-2, Class B-3 and Class C-PPP Certificates, will bertgage related securities for purposes of the Secondary Mortgage Market Enhancement Act of 1984.

Certain Legal Investmentects in this prospectusplement for importantrmation concerningible restrictions on ownershipe offered certificates

egulated institutions. You should consult with your own legal advisorstermining whether and to what extent the offered certificates constitute legal investments for you.


8/2/2019 WMALT 2007-4

17/394


SA CONSIDERATI ONS

ect to important considerations described under ERISA Considerations in this prospectus supplement and in the accompanying prospectus, the

S-12


8/2/2019 WMALT 2007-4

18/394


ed certificates, other than the Class C-PPP and Class R Certificates, will be eligible for purchase by persons investing assets of employeeefit plans or individual retirement accounts. See ERISAsiderations in thispectus supplement and inaccompanying prospectus.

ERAL I NCOME TAX CONSEQUENCES

ederal income tax purposes, one or more REMIC elections will be made with respect to the Trust. The offered certificates, other than thes R and Class C-PPP Certificates, will represent ownership of REMIC regular interests, and will generally be treated as representing ownershipebt for federal income tax purposes. You will be required to include in income all interest and original issue discount on these certificatescordance with the accrual method of accounting regardless of your usual methods of accounting. For federal income tax purposes, the

s R Certificates will represent ownership of REMIC residual interests. The Class C-PPP Certificates will not represent an interest in any REMIC.urther information regarding the federal income tax consequences of investing in the offered certificates, including importantmation regarding the tax treatment of the Class R Certificates, see

Material Federal IncomeConsequences in thispectus supplement and inaccompanying prospectus.

I NGS

a condition to the issuance of the offered certificates that they receive the following ratings from Standard & Poors Ratings Services, a divisionhe McGraw-Hill Companies, Inc., and Moody s Investors Service:

Rating Agency S&P Moodys

A-1 AAA Aaa

A-2 AAA Aa1

A-3 AAA Aaa

A-4 AAA Aa1

A-5 AAA Aaa

A-6 AAA Aaa

A-7 AAA Aaa

A-8 AAA Aaa

A-9 AAA Aaa

A-10 AAA Aaa

A-11 AAA Aaa

A-12 AAA Aaa

A-13 AAA AaaA-1 AAA Aaa

A-2 AAA Aaa

A-3 AAA Aa1

A-4 AAA Aaa

X AAA Aaa

P AAA Aaa

1 AA

2 A

3 BBB AAA Aaa

PPP AAA Aaa

ratings on the offered certificates address the likelihood of the receipt by holders of the offered certificates of all distributions on theerlying mortgage loans to which they are entitled. They do not address the likely actual rate of prepayments. The rate of prepayments, ifrent than originally anticipated, could adversely affect the yield realized by holders of the offered certificates or cause the holders ofcertificates entitled to interest only to fail to recover their initial investment.

ratings assigned to the Class C-PPP do not address any assessment of the likelihood or frequency of prepayments on the related mortgages or the likelihood of receipt of prepayment penalty payments and only address the return of the Class C-PPP principal balance of $100.

S-13


8/2/2019 WMALT 2007-4

19/394


RI SK FACTORS

offered certificates are not suitable investment s for all investors. I n part icular, you should not purchase any class ofred certificates unless you understand and are able to bear t he prepayment, credit, l iquidity and market risks associated that class.

offered certificates are complex securities and it is import ant t hat you p ossess, either alone or toget her w ith y oursors, including your accountant s, the expertise necessary to evaluate t he inform ation contained in this prospectus

plement and the accompanying prospectus in the context of your financial situation.

re is No Guarant ee That You Will Receive Princip al PaymentsYour Cert ificat es at any Specific Rate or on an y Specific Dates

As the mortgagors make payments of interest and principal on their mortgage loans, you wreceive payments. Because the mortgagors are free to make those payments faster thanscheduled, you may receive distributions faster than you expected. There is no guarantee t

will receive principal payments on your certificates at any specific rate or on any specific daLack of Secondary Markets May Make it Difficult for You t o

ell Your Certi ficates and Your I nvestm ent May Lose Value The underwriter may make a secondary market in the classes of offered certificates actuallypurchased by it, but it has no obligation to do so. There is no assurance that such a secondmarket will develop or, if it develops, that it will continue. Consequently, you may not be absell your certificates readily or at prices that will enable you to realize your desired yield. Thmarket values of the offered certificates are likely to fluctuate; these fluctuations may besignificant and could result in significant losses to you.

Investments can lose value because of actual performance as well as perceptions of futureperformance based on changes in the external interest rate environment and other market not directly related to the performance of the mortgage loans themselves.

The secondary markets for asset-backed securities have experienced periods of illiquidity anbe expected to do so in the future. Illiquidity can have a severely adverse effect on the pricsecurities that are especially sensitive to prepayment, credit, or interest rate risk, or that hastructured to meet the investment requirements of limited categories of investors.

ent Developments in t he Residential Mort gage Market Mayersely Affect the Return on Your Certificates

Recently, the residential mortgage market in the United States has experienced a variety ofdifficulties and changed economic conditions that may adversely affect the yield on yourcertificates. Delinquencies and losses with respect to residential mortgage loans generally hincreased in recent months, and may continue to increase. In addition, in recent months hoprices in many states have declined or stopped appreciating, after extended periods of signappreciation. A continued decline or an extended flattening of those values may result in adincreases in delinquencies and losses on residential mortgage loans generally, particularly wrespect to second homes and investor properties and

S-14


8/2/2019 WMALT 2007-4

20/394


with respect to any residential mortgage loans whose aggregate loan amounts (includingsubordinate liens) are close to or greater than the related property values. You should cothat the general market conditions discussed above may affect the performance of themortgage loans and may adversely affect the return on your certificates.

Yield on Your Certi ficat es is Directly Related t o the Prepaymente on the Related Mortgage Loans

The yield to maturity on your certificates is directly related to the rate at which the mortpay principal on the related mortgage loans. Principal payments on the mortgage loans min the following forms:

scheduled principal payments; and

principal prepayments, which consist of:

prepayments in full on a mortgage loan;

partial prepayments on a mortgage loan; and

liquidation principal, which is the principal recovered after foreclosing on orotherwise liquidating a defaulted mortgage loan.

In general, if prevailing mortgage interest rates decline significantly below the mortgagerates on the mortgage loans in the mortgage pool, the prepayment rate may increase. Pfor early prepayment may also affect the prepayment rate, as they may discourage mortfrom prepaying their mortgage loans during the period such prepayment penalties are ineven in a declining interest rate environment. See Description of theMortgage Pool and the Prepayment Penalty

Amount and Term tablesin Appendix B in this

prospectus supplementfor a description ofprepayment penaltiesimposed on the mortgageloans. General economic conditions and homeowner mobility will also athe prepayment rate. Each mortgage loan contains a due-on-sale clause; however, theis prohibited from exercising that due-on-saleclause if prohibited by applicable law or conditions specified in the mortgage note are satisfied. If the due-on-sale clause is exethe sale of a mortgaged property will cause a prepayment in full on the related mortgagSee Yield andPrepaymentConsiderations in thisprospectus supplementand Yield and MaturityConsiderations in theaccompanying prospectus.prepayment rate may affect the yield on all of the offered certificates. However, if you hpurchased a certificate that receives only distributions of interest or only distributions ofprincipal, the prepayment rate will be especially important to you.

From time to time, the servicer may implement programs to solicit mortgagors of qualifymortgage loans that it services for refinance, including mortgage loans underlying thecertificates. While those programs will not specifically target the mortgage loans underly

S-15


8/2/2019 WMALT 2007-4

21/394


the certificates for refinance, they may have the effect of accelerating the prepayment ratethose mortgage loans, which would adversely affect the yield on all classes of certificatespurchased at a premium, particularly those certificates only entitled to interest.

As described in this prospectus supplement, distributions on the certificates related to loan will be calculated on the basis of collections on specified subgroups of the mortgage loans loan group, and those subgroups were determined based on the mortgage interest rates ofmortgage loans. Investors in a certificate should consider that the characteristics of the relasubgroup will have particular bearing on the prepayment characteristics of those mortgage In particular, a subgroup with a higher average mortgage interest rate may be expected toexperience higher rates of prepayment than a subgroup with a lower average mortgage intrate. See Description of the

Certificates

Distributionsof Principal in thisprospectus supplement.

Optional Terminat ion Would Adversely Affect t he Certif icatest Receive Only Distributions of I nterest or That Werechased at a Premiu m

When the aggregate principal balance of the mortgage loans has been reduced to less thanof that balance as of May 1, 2007, the servicer may purchase all of the mortgage loans, whresult in the retirement of the certificates. The servicer will have this right even if the aggreprincipal balance of the mortgage loans in any particular loan group or subgroup is greater 10% of that balance as of May 1, 2007. See Description of theCertificates OptionalTermination in thisprospectus supplement. If thishappens, the purchase price paid by the servicer will be passed through to the certificatehoThis would have the same effect as if all of the remaining mortgagors made prepayments in

Any class of certificates purchased at a premium could be adversely affected by an optionapurchase of the mortgage loans. Sincethe Class C-X Certificates receive only distributions o

interest, an optional termination would adversely affect holders of those certificates.id Prepayment s Will Reduce the Yield on th e Class C-Xificates

Payments to the holders of the Class C-X Certificates come only from interest payments on of the mortgage loans in each loan group. These mortgage loans are called premium ratemortgage loans because, in general, they have the highest mortgage interest rates in the ploan group. In general, the higher the mortgage interest rate is on a mortgage loan, the minterest the Class C-X Certificates receive from that mortgage loan. If mortgage interest ratdecline below the interest rates on the premium rate mortgage loans, these premium ratemortgage loans are more likely to be refinanced, and, therefore, prepayments in full on themortgage loans are more likely to occur. Since the Class C-X Certificates receive their interepayments only from the premium rate mortgage loans that are still

S-16


8/2/2019 WMALT 2007-4

22/394

8/2/2019 WMALT 2007-4

23/394


In addition, because these certificates may be outstanding for a relatively long period of timthere is a greater likelihood that they will remain outstanding after the termination of the csupport provided by the subordinate certificates and, therefore, be more susceptible to lossthe related mortgage loans. When considering investing in these certificates, you should cowith your financial advisor regarding the associated risks.

i ficat es Bought at Premium s and Discount s May Receive aer Yield Than Expected

If you purchase a certificate at a discount from its original principal balance and the rate ofprincipal payments is slower than you expect, your yield may be lower than you anticipate.purchase a certificate at a premium over its original principal balance and the rate of principayments is faster than you expect, your yield may be lower than you anticipate.

ses on the Mort gage Loans Will Reduce the Yield on theated Certificates

The yield to maturity on the Class B-1, Class B-2 and Class B-3 Certificates will be extremelsensitive to losses on the mortgage loans. After the aggregate principal balance of the ClasClass B-5 and Class B-6 Certificates has been reduced to zero, losses on the mortgage loanallocated exclusively to the Class B-3, Class B-2 and Class B-1 Certificates, in that order.

In addition, if the aggregate principal balance of the subordinate certificates has been reduzero, all further losses on the mortgage loans will be allocated to the related senior certifica

The yield to maturity on the Class 1-A-2 Certificates may become extremely sensitive to losthe subgroup 1-1 loans, because losses that would otherwise be allocated to the Class 1-A-1-A-7, Class 1-A-8, Class 1-A-9, Class 1-A-10, Class 1-A-11 and Class 1-A-12 Certificates wiinstead first be allocated to the Class 1-A-2 Certificates.

The yield to maturity on the Class 1-A-4 Certificates may become extremely sensitive to losthe subgroup 1-2 loans, because losses that would otherwise be allocated to the Class 1-A-Certificates will instead first be allocated to the Class 1-A-4 Certificates.

The yield to maturity on the Class 1-A-6 Certificates may become extremely sensitive to losthe subgroup 1-3 loans, because losses that would otherwise be allocated to the Class 1-A-Certificates will instead first be allocated to the Class 1-A-6 Certificates.

The yield to maturity on the Class 2-A-3 Certificates may become extremely sensitive to losthe group 2 loans, because losses that would otherwise be allocated to the Class 2-A-1, Claand Class 2-A-4 Certificates will instead first be allocated to the Class 2-A-3 Certificates.

S-18


8/2/2019 WMALT 2007-4

24/394


See Description of theCertificates Subordination and

Allocation of Losses inthis prospectussupplement.

ses on the Mort gage Loans in Subgroup 1- 1, Subgr oup 1-2 ,gr oup 1- 3 or Loan Group 2 May Reduce the Yield on Seniorificates Unrelated to that Loan Group or Subgroup

Because the Class B Certificates represent interests in each subgroup of loan group 1, as wloan group 2, the class principal balances of those certificates could be reduced to zero as aof realized losses on the mortgage loans in any loan group or subgroup. Therefore, the alloof realized losses on the mortgage loans in any loan group or subgroup to the Class B Certi

will reduce the subordination provided by the subordinate certificates to all of the seniorcertificates, including the senior certificates related to the loan group or subgroup that did nsuffer any losses. This will increase the likelihood that future realized losses may be allocatethe senior certificates related to a loan group or subgroup that did not suffer any previous l

See Description of theCertificates Subordination and

Allocation of Losses inthis prospectussupplement.

In terest Only Loans Have a Greater Degree of Risk if a Defaulturs Because They do not Provide for any Payment s ofeduled Principal Until the Tenth Anniversary of their First Duees

Approximately 43.4% of the subgroup 1-1 loans, approximately 53.0% of the subgroup 1-2and approximately 71.2% of the subgroup 1-3 loans (in each case, by principal balance as 1, 2007) do not provide for any payments of scheduled principal until the tenth anniversarydate on which their initial monthly payment is due. Until that date, monthly payments on th

mortgage loans will be comprised solely of interest accrued on the outstanding principal bathe mortgage loan during the preceding calendar month. Since the mortgagors are not reqmake scheduled principal payments on these mortgage loans during this ten year period, thprincipal balance of the mortgage loan will likely be higher than the principal balance of a smortgage loan which requires the payment of both principal and interest throughout the enterm of the mortgage loan. A higher principal balance may result in a greater loss upon theliquidation of the mortgage loan due to a default.

Geographic Concentration of t he Mort gaged Propertiesating to the Mort gage Loans Increases Your Exposure toerse Condit ions in Califor nia and Other States

The geographic concentration of mortgaged properties can expose the related mortgage lohigher incidence of losses due to a greater susceptibility to hazards not covered by standarhazard insurance, such as hurricanes, floods, mudslides and earthquakes, than properties lin other parts of the country. Also, the geographic concentration of mortgaged properties cexpose the related mortgage loans to a higher incidence of losses due to economic conditiostates that have higher concentrations of businesses in particular economic segments than nation as a whole.

Consequently, the high concentration of mortgaged properties in California and other states

adversely affect losses and prepayments on the mortgage loans

S-19


8/2/2019 WMALT 2007-4

25/394


which, in turn, would adversely affect the certificates. SeeAppendix B for a tableshowing the geographicdistribution by state ofthe mortgaged propertiesin each loan group andsubgroup.

oss or Delinquen cy on a Mort gage Loan May Have aproportionat e I mpact on th e Performance of the Mortgage Poolause the Mor tgag e Loans Have High Principal Balances

As of May 1, 2007, the highest principal balance of any mortgage loan was approximately$1,992,531, and approximately 7.7% of the mortgage loans (by aggregate principal balanMay 1, 2007) had original principal balances greater than or equal to $1,000,000.

You should consider the risk that the loss and delinquency experience on the higher balanmortgage loans related to your certificates may have a disproportionate effect on the relamortgage loans as a whole. A loss of the entire principal balance of one of these mortgagmay result in a substantial realized loss, which may be allocated to the related offeredcertificates. See Appendix B for atable showing the rangeof original principalbalances of themortgaged loans in eachloan group and subgroup.

ders of Exchangeable Cert ificat es May be Unable t o Exchanger Certificates

Investors in exchangeable certificates are encouraged to consider a number of factors thalimit a certificateholders ability to exchange their certificates for other exchangeable certif

At the time of the proposed exchange, a certificateholder must own ExchangeableCertificates of the related class or classes in the proportions necessary to make the exchange.

A certificateholder that does not own the Exchangeable Certificates necessary for thdesired exchange may be unable to obtain those certificates, since the holder of thocertificates may be unwilling to sell those certificates at a reasonable price (or at anor may be unable to sell them.

Principal distributions and reductions in notional amounts will decrease the principalbalances and notional amounts of Exchangeable Certificates available for exchange time.

The Exchangeable Certificates may not have a denomination less than the applicablminimum denomination for those certificates.

All Mort gage Loans Im pose Prepaym ent Penalties, and Thoset Do I mpose Them for Only a Limited Period of Time

As of May 1, 2007, certain of the mortgage loans impose penalties for early prepayments (but do not impose penalties for partial prepayments) received on or before the third annas stated in the related mortgage note, of the origination of the mortgage loan. As of May2007, certain of the mortgage loans impose penalties for early prepayments in full, and foprepayments in the event that aggregate partial prepayments made during a 12-month peexceed a certain percentage of the original principal balance. The amount of the applicabl

prepayment penalty, to the extent permitted by applicable law, is as provided in the

S-20


8/2/2019 WMALT 2007-4

26/394


related mortgage note. Such prepayment penalty may discourage mortgagors from prepayimortgage loans during the period such prepayment penalties are in effect and, accordinglythereby affect the rate of prepayment of such mortgage loans even in a declining interest renvironment. See the PrepaymentPenalty Amount and Termof the Subgroup 1-1Loans, PrepaymentPenalty Amount and Termof the Subgroup 1-2Loans, PrepaymentPenalty Amount and Termof the Subgroup 1-3

Loans and PrepaymentPenalty Amount and Termof the Group 2 Loans tables in Appendix B forinformation regarding thenumber of loans, and therelated percentage ofeach loan group orsubgroup, that containprepayment penalties,broken out for each ofthe various prepaymentpenalty terms.

y Penalt ies on Volunt ary Prepayment s in Full Will Be Paid toClass C-PPP Cert ificat eholders

The Class C-PPP Certificates will receive $100 of principal on the distribution date in May 20the Class C-PPP Reserve Fund. These certificates will not receive any distributions of intereswill they receive distributions of principal on any other distribution date. The only other pay

the Class C-PPP Certificates are entitled to receive are the Assigned Prepayment Penalties.

The Assigned Prepayment Penaltieswith respect to a distribution date will equal the (a) all prepayment penalty payments remitted to the Trust with respect to voluntary fullprepayments on the mortgage loans that have prepayment penalties during the PrepaymenPenalty Period and (b) any amounts paid by the servicer during the Prepayment Penalty Pepursuant to the pooling agreement if the servicer waives a penalty on a voluntary full prepaof a mortgage loan other than in accordance with the standards set forth in the poolingagreement, or paid by Washington Mutual Mortgage Securities Corp. during the PrepaymenPenalty Period pursuant to the mortgage loan sale agreement if it breaches certain represeand warranties with respect to mortgage loans that require payment of a penalty on voluntprepayment.

The holders of the Class C-PPP Certificates will not receive any prepayment penalty paymencollected by the servicer with respect to voluntary partial prepayments; each such paymentretained by the servicer as additional servicing compensation. The servicer will also not collprepayment penalties due to involuntary prepayments such as foreclosures.

In addition, in the event of a material breach of the representations and warranties made bdepositor or Washington Mutual Mortgage Securities Corp. with respect to the mortgage loabreaching party may be required to repurchase the affected mortgage loan from the Trust substitute a new mortgage loan for that mortgage loan). The holders of the Class C-PPP

S-21


8/2/2019 WMALT 2007-4

27/394


Certificates will not receive any prepayment penalties collected on a mortgage loan that warepurchased or substituted for.

No prepayment penalty payments will be available for distribution to holders of the other clcertificates.

re are Limit ations in the Mortgage Loans on the I mposition ofpayment Penalties; Washington Mut ual Bank May Waivepayment Penalt ies Under Certain Circumstances

Some of the mortgage loans that impose penalties for voluntary full prepayments contain aexception for prepayments made in connection with a bona fide sale of the mortgaged propunderlying the mortgage loan during a certain period, and therefore penalties are not imposuch prepayments and are not available for distribution to the Class C-PPP Certificates.

In addition, under certain circumstances set forth in the pooling agreement, the payment ootherwise applicable penalty for voluntary full prepayment by a mortgagor may be waived b

servicer and, if waived in accordance with the terms of the pooling agreement, the amountwaived penalty will not be available for distribution to the holders of the Class C-PPP CertifiCircumstances under which the servicer may waive a prepayment penalty include, among ocircumstances set forth in the pooling agreement, (i) some cases, for mortgage loans originthe servicer or an affiliate thereof, where the mortgagor sells the mortgaged property and oa new mortgage loan originated and serviced by the servicer to purchase another propertyprovided that the prepayment is made no earlier than one year after origination, and (ii) socases, for mortgage loans originated by the servicer or an affiliate thereof, with prepaymenpenalty terms longer than one year, where the mortgagor refinances the mortgage loan witnew mortgage loan originated and serviced by the servicer, provided that 90 days or less rethe prepayment penalty term.

Moreover, regardless of th e terms of t he mort gage note, the servicer w il l not colprepayment penalties required to be paid more than t hree years after t he originof the mort gage loan.

Investors should conduct their own analysis of the effect that the payment of penalties for

voluntary full prepayment of the related mortgage loans, or decisions by the servicer with rto waiver thereof, may have on the performance of the Class C-PPP certificates. See alsoDescription of the Mortgage Pool, the Prepayment Penalty Amount and Term tables in AB and Description of the CertificatesDistributions to the Class C-PPP Certificates in thisprospectus supplement for a description of prepayment penalties imposed on the related mloans.

Lack of Physical Certi ficates f or Certain Classes of Certif icates Cause Delays in Payment

You will no t have a physical certificate if you own an offered certificate, other than a Class Certificate. As a result, you will be able to transfer your certificates only through The DeposTrust Company, participating

S-22


8/2/2019 WMALT 2007-4

28/394


organizations, including Euroclear and Clearstream, and indirect participants. In addition, yoexperience some delay in receiving distributions on these certificates because the trustee wsend distributions directly to you. Instead, the trustee will send all distributions to The DepTrust Company, which will then credit those distributions to the participating organizations.organizations will in turn credit accounts you have either directly with them or indirectly witthrough indirect participants.

Retur n on Your Certifi cates Could be Reduced due t o th elication of t he Servicemem bers Civil Relief Act or any

mparable State Legislation

Following the terrorist attacks in the United States on September 11, 2001, the United Statincreased its active military operations (including, most recently, significant military actions and has placed a substantial number of military reservists and members of the National Guactive duty status. It is possible that the number of reservists and members of the Nationalplaced on active duty status in the near future may increase. Calling reservists, members of

National Guard and civilians to active military duty may adversely affect the performance ofcertificates. Under the Servicemembers Civil Relief Act, as amended (the Relief Act), forknown as the Soldiersand SailorsCivil Relief Act of 1940, persons in active military serviceprovided relief from the performance of some payment obligations. The relief includes a 6.0per annum interest rate cap on each mortgage loan, provided that the mortgage loan was obefore the commencement of active military service. In addition, all civil court actions, suchbankruptcy and foreclosure proceedings, are delayed. Furthermore, the servicer may be reqto waive all or part of any prepayment penalty that would otherwise be due during the timeany mortgage loan is subject to the Relief Act.

State legislation may provide similar relief for military personnel placed on active duty statuthe purpose of this prospectus supplement, references to the Relief Act include any suchcomparable state legislation.

The application of the interest rate cap to any mortgage loan underlying the certificates woresult in certificateholders receiving less interest than they would otherwise be entitled to. Tinterest shortfall on any distribution date arising out of each of these mortgage loans wouldequal to one month of interest on the principal balance of the mortgage loan at a rate equadifference between the interest rate payable by the borrower under the terms of the applicmortgage note and 6.000%. The interest shortfall in each loan group would be deducted frinterest payable to each class of certificates related to that loan group, pro rata, in accordainterest accrued on each class of certificates for the applicable distribution date. This intereshortfall is not covered by compensating interest.

S-23


8/2/2019 WMALT 2007-4

29/394


The effect of a delay in foreclosure proceedings with respect to any mortgage loan underlycertificates could be to cause a loss, or increase the severity of any loss that would have otoccurred, upon the final liquidation of the mortgage loan. These losses would be applied torelated certificates in the order described in Description of the CertificatesSubordination

Allocation of Losses in this prospectus supplement.

Neither the depositor nor the servicer is able to determine how many of the mortgage loanunderlying the certificates are or may be affected by application of the Relief Act in the futu

Conservat orship, Receivership, or I nsolvency of Washingt onu al Bank as Mort gage Loan Seller Could Result I n Delayed oruced Distributions on the Certificates

I n addition t o th e applicable risk f actors described in theaccompanyin g prospectu s, investors should consider th e follorisk factor:

In the receivership of an unrelated national bank, the FDIC successfully argued that certainrights and powers extended to a statutory trust formed by that national bank in connectionsecuritization of credit card receivables. If Washington Mutual Bank were to enter conservaor receivership, the FDIC could argue that its rights and powers extend to the depositor or Trust. If the FDIC were to take this position and seek to repudiate or otherwise affect the rthe trustee or the holders of the certificates under any transaction document, delays or redin distributions on the certificates could result.

There could also be delays or reductions in distributions on the certificates if the FDIC succasserts that a statutory injunction automatically prevents the Trust, the trustee, and the hothe certificates from exercising their rights, remedies, and interests for up to 90 days.

S-24


8/2/2019 WMALT 2007-4

30/394


THE SPONSOR

eral

hington Mutual Mortgage Securities Corp., the sponsor of the securitization transaction, is a Delaware corporation and a wholly-ownedidiary of Washington Mutual Bank and an indirect wholly-owned subsidiary of Washington Mutual, Inc. At March 31, 2007, Washington

ual, Inc. and its subsidiaries had assets of $320.0 billion. The sponsor engages in the business of (i) purchasing mortgage loans on acing retained and servicing released basis, (ii) selling mortgage loans in whole loan transactions and securitizing mortgage loans throughated and unaffiliated depositors, (iii) master servicing mortgage loans, (iv) acting as administrative agent of Washington Mutual Bank andffiliates with respect to mortgage loans serviced by Washington Mutual Bank and its affiliates and (v) providing securitization services.sponsor generally acts as master servicer or administrative agent with respect to all mortgage loans securitized by the sponsor.

ritization of mortgage loans is an integral part of the sponsors conduit program. It has engaged in securitizations of first lien single-y residential mortgage loans through WaMu Asset Acceptance Corp., as depositor, since 2005, and has acted as its own depositor from 19792005.

sponsor participated with the underwriter in structuring the securitization transaction.

following table shows, for each indicated period, the aggregate principal balance of first and second lien single-family residential mortgages purchased by the sponsor during that period (except mortgage loans purchased in its capacity as depositor from an affiliated sponsor) andportion of those mortgage loans securitized during that period in securitization transactions for which it or WaMu Asset Acceptance Corp. actedepositor.

The Sponsor s Purchase and Securit ization of Single- Family Residenti al Mortg age Loans

Year EndedDecember 31, 2005

Year EndedDecember 31, 2006

Three Mont hs EnMarch 31, 2007

(Dollar Amounts in Milli ons)

gregate Principal Balance of Mortgage Loans Purchased by Sponsor $

11,265 $

24,861 $

7

gregate Principal Balance of Mortgage Loans Securitized $

7,149 $

17,051 $

5

Sponsor s Origination Channels

sponsor purchases mortgage loans from Washington Mutual Bank and from approved mortgage loan sellers. All of the mortgage loans ownedhe Trust were purchased by the sponsor from Washington Mutual Bank, and therefore Washington Mutual Bank is the only mortgage loanr as used in this prospectus supplement and the accompanying prospectus.

ugh the sponsors conduit program, the sponsor purchases mortgage loans in bulk from approved mortgage loan sellers on both acing retained and servicing released basis. In initially approving a mortgage loan seller, the sponsor takes into account the following:

ual origination volume, tenure of business and key staff in originating loans, policies and procedures for originating loans including qualityrol and appraisal review, review audits performed on mortgage loan seller by rating agencies, regulatory agencies and governmentsored entities, the mortgage loan sellers financial statements, errors and omissions insurance coverage and fidelity bond and liabilityrance coverage. Approved mortgage loan sellers financial statements, insurance coverage and new review audits are reviewed on anual basis. Additionally, the sponsor performs a monthly ongoing performance review of previously purchased mortgage loans for trendslinquencies, losses and repurchases. The mortgage loan sellersunderwriting guidelines are reviewed for consistency with the sponsorst parameters and conformity with the underwriting standards described under Underwriting of the Mortgage Loansbelow and are

er approved or approved with exceptions. The mortgage loan sellers represent to the sponsor upon sale that the mortgage loans have underwritte

WMALT 2007-4

Documents

Transcript of WMALT 2007-4