Fitch Rates $947.2MM HSI Asset Securitization Corp. Trust 2006-OPT4.

NEW YORK -- HSI Asset Securitization Corporation Trust 2006-OPT4, which closed on April 28, 2006, is rated by Fitch Ratings as follows:

-- $753.3 million classes A-IO, I-A, and II-A-1 to II-A-5 (senior certificates) 'AAA';

-- $71.0 million class M-1 'AA+';

-- $20.6 million class M-2 'AA+';

-- $17.8 million class M-3 'AA';

-- $16.8 million class M-4 'AA-';

-- $15.8 million class M-5 'A';

-- $14.9 million class M-6 'A-';

-- $13.4 million class M-7 'BBB+';

-- $9.1 million class M-8 'BBB';

-- $4.8 million privately offered class M-9 'BBB-';

-- $9.6 million privately offered class M-10 'BB'.

The 'AAA' rating on the senior certificates reflects the 21.50% total credit enhancement provided by 7.40% class M-1, the 2.15% class M-2, the 1.85% class M-3, the 1.75% class M-4, the 1.65% class M-5, the 1.55 % class M-6, the 1.40% class M-7, the 0.95% class M-8, the 0.50% privately offered class M-9, the 1.00% privately offered class M-10 and the 1.30% initial and target overcollateralization (OC). All certificates have the benefit of monthly excess cash flow to absorb losses. In addition, the ratings reflect the quality of the loans, the integrity of the transaction's legal structure as well as the capabilities of Option One Mortgage Corporation as servicer. Deutsche Bank National Trust Company is the trustee.

The certificates are supported by two collateral groups. Group I mortgage loans consists of first lien (95.01%) and second lien (4.99%) fixed-rate and adjustable-rate loans with a cut-off principal balance of $371,365,682 that conforms to Fannie Mae loan limits. Approximately 23.09% of the mortgage loans are fixed-rate mortgage loans, 76.91% are adjustable-rate mortgage loans and 11.22% are interest-only rate mortgage loans. The weighted average loan rate is 7.831% and the weighted average remaining term to maturity (WAM) is 355 months. The remaining WAM for the Group I interest-only mortgage loans is 56 months. The average outstanding principal balance of the loans is $173,942, the weighted average original combined loan-to-value ratio (CLTV) of 80.13% and the weighted average credit score is 618. The properties are primarily located in California (20.93%), Florida (11.93%) and New York (10.62%).

Group II mortgage loans consists of first lien (96.53%) and second lien (3.47%) fixed-rate and adjustable-rate loans with a cut-off principal balance of $604,702,429 that may or may not conform to Fannie Mae loan limits. Approximately 15.68% of the mortgage loans are fixed-rate mortgage loans, 84.32% are adjustable-rate mortgage loans and 25.26% are interest-only rate mortgage loans. The weighted average loan rate is 8.198% and the WAM is 356 months. The WAM for the interest-only mortgage loans is 57 months. The average outstanding principal balance of the loans is $213,449, the weighted average OLTV ratio of 85.34% and the weighted average credit score is 624. The properties are primarily located in California (28.58%), Florida (9.85%) and New York (9.41%).

All of the mortgage loans were originated by Option One Mortgage Corporation. Incorporated in 1992, Option One began originating and servicing subprime loans in February 1993. Option One is a subsidiary of Block Financial, which is a subsidiary of H&R Block, Inc. For federal income tax purposes, multiple real estate mortgage investment conduit (REMIC) elections will be made with respect to the trust estate.

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