Fitch Rates MASTR Adjustable Rate Mtge Trust P-T Ctfs $2.003B Series 2006-OA2.

NEW YORK -- Mortgage Asset Securitization Transactions (MASTR) Adjustable Rate Mortgages Trust 2006-OA2 mortgage pass-through certificates (closed on November 15, 2006) is rated by Fitch as follows:

-- $1.813 billion classes 1-A-1 to 1-A-3, 2-A-1 to 2-A-3, 3-A-1, 3-A2, 4-A1A to 4-A-2, X-1, X-2, and XW certificates 'AAA' (senior certificates);

-- $46.31 million class M-1 'AA+';

-- $42.28 million class M-2 'AA';

-- $14.09 million class M-3 'AA-';

-- $31.21 million class M-4 'A';

-- $18.12 million class M-5 'BBB+';

-- $12.08 million class M-6 'BBB';

-- $11.07 million class M-7 'BBB-';

-- $15.1 million privately offered class M-8 'BB';

The 'AAA' rating on the senior certificates reflects the 9.95% subordination provided by the 2.30% class M-1, the 2.10% class M-2, the 0.70% class M-3, the 1.55% class M-4, the 0.9% class M-5, the 0.6% class M-6, the 0.55% class M-7, the 0.75% privately offered class M-8 certificates, and initial and target overcollateralization (OC) of 0.5%.

Fitch believes the above credit enhancement will be adequate to support mortgagor defaults as well as bankruptcy, fraud and special hazard losses in limited amounts. In addition, the ratings also reflect the quality of the underlying mortgage collateral, strength of the legal and financial structures and the master servicing capabilities of Wells Fargo Bank Minnesota, N.A., which is rated 'RMS1' by Fitch Ratings.

The trust will consist of four asset groups. The trust in aggregate contains 5,660 adjustable-rate, closed-end, first liens on one to four family residential properties, all which are negatively amortizing loans, with an aggregate scheduled principal balance of $2,013,321,248. The average unpaid principal balance of the aggregate pool as of the cut-off date (October 1, 2006) is $355,710. The weighted average original loan-to-value ratio (OLTV) is 76.21%. The weighted average credit score of the borrowers is 704. The weighted average mortgage interest rate is 5.062% and the weighted average remaining term to maturity is 390 months. The states that represent the largest portion of the aggregate mortgage loans are California (53.19 %), and Florida (11.24%). All other states represent less than 5% of the aggregate balance as of the cut-off date.

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

MASTR, a special purpose corporation, deposited the loans into the trust, which issued the certificates. U.S. Bank National Association will act as trustee. For federal income tax purposes, elections will be made to treat the trust fund as multiple real estate mortgage investment conduits (REMICs).

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