Fitch Rates Wells Fargo's $420MM P-T Ctfs Series 2007-AR4

The 'AAA' rating on the senior certificates reflects the 4.50%subordination provided by the 1.90% class B-1, 1.00% class B-2, 0.40%class B-3, 0.60% privately offered class B-4, 0.20% privately offeredclass B-5, and 0.40% privately offered class B-6. The class B-6 is notrated by Fitch.

Fitch believes the amount of credit enhancement available will besufficient to cover credit losses. The ratings also reflect the highquality of the underlying collateral, the integrity of the legal andfinancial structures, and the servicing capabilities of Wells FargoBank, N.A. (WFB; rated 'RPS1' by Fitch).

The transaction is secured by a pool of mortgage loans, whichconsists of fully amortizing, one- to four-family, adjustable-ratemortgage loans that provide for a fixed interest rate during aninitial period of approximately five years. Thereafter, the interestrate will adjust on an annual basis. The interest rate of eachmortgage loan will adjust to equal the sum of the index and a grossmargin. Approximately 91.35% of the mortgage loans are interest-onlyloans, which require only payments of interest until the monthfollowing the first adjustment date.

The mortgage loans have an aggregate principal balance ofapproximately $421,914,997 as of the cut-off date (August 1, 2007), anaverage balance of $562,553 a weighted average remaining term tomaturity (WAM) of 357 months, a weighted average originalloan-to-value ratio (OLTV) of 74.95%, and a weighted average coupon(WAC) of 6.292%. Rate/Term and equity take-out refinances account for26.01% and 16.94% of the loans, respectively. The weighted averageoriginal FICO credit score of the loans is 739. Owner-occupiedproperties and second homes comprise 93.13% and 6.66% of the loans,respectively. The states that represent the largest geographicconcentration are California (57.72%) and Florida (5.59%). All otherstates represent less than 5% of the aggregate pool balance as of thecut-off date.

None of the mortgage loans are 'high cost' loans as defined underany local, state or federal laws. For additional information onFitch's rating criteria regarding predatory lending legislation,please see the press release issued May 1, 2003 entitled 'FitchRevises Rating Criteria in Wake of Predatory Lending Legislation',available on the Fitch Ratings web site at .

All of the mortgage loans were generally originated in conformitywith underwriting standards of WFB. WFB sold the loans to Wells FargoAsset Securities Corporation (WFASC), a special purpose corporation,which deposited the loans into the trust. The trust issued thecertificates in exchange for the mortgage loans. WFB will act asservicer, master servicer, paying agent, and custodian, and HSBC BankUSA, N.A. will act as trustee. For federal income tax purposes,elections will be made to treat the trust as a real estate mortgageinvestment conduit (REMIC).

Fitch's rating definitions and the terms of use of such ratingsare available on the agency's public site, www.fitchratings.com.Published ratings, criteria and methodologies are available from thissite, at all times. Fitch's code of conduct, confidentiality,conflicts of interest, affiliate firewall, compliance and otherrelevant policies and procedures are also available from the 'Code ofConduct' section of this site.