Fitch Affirms $3.5B and Downgrades $226.4MM from CSFB HEAT Subprime Transactions.

NEW YORK -- Fitch Ratings has taken the following rating actions on CSFB HEAT mortgage pass-through certificates. Affirmations total $3.5 billion and downgrades total $226.4 million. Break Loss percentages (BL) and Loss Coverage Ratios (LCR) for each class are included with the rating actions as follows:

CSFB HEAT 2006-1

--$341.2 million class A affirmed at 'AAA' (BL: 41.11, LCR: 4.59);

--$28.8 million class M-1 affirmed at 'AA+' (BL: 32.45, LCR: 3.62);

--$26.4 million class M-2 affirmed at 'AA' (BL: 29.48, LCR: 3.29);

--$18 million class M-3 affirmed at 'AA-' (BL: 26.24, LCR: 2.93);

--$12.4 million class M-4 affirmed at 'A+' (BL: 23.80, LCR: 2.66);

--$12.8 million class M-5 affirmed at 'A' (BL: 21.28, LCR: 2.38);

--$11.2 million class M-6 affirmed at 'A-' (BL: 19.01, LCR: 2.12);

--$10.4 million class M-7 affirmed at 'A-' (BL: 16.81, LCR: 1.88);

--$10 million class M-8 affirmed at 'BBB+' (BL: 14.75, LCR: 1.65);

--$7.6 million class B-1 affirmed at 'BBB' (BL: 13.27, LCR: 1.48);

--$7.2 million class B-2 affirmed at 'BBB-' (BL: 12.01, LCR: 1.34);

--$6.4 million class B-3 affirmed at 'BB+' (BL: 9.88, LCR: 1.1).

Deal Summary

--Originators: 48.5% Wells; 15.48% Aames, 10.7% Encore, 6.7% OwnIt;

--60+ day Delinquency: 13.66%;

--Realized Losses to date (% of Original Balance): 0.56%;

--Expected Remaining Losses (% of Current Balance): 8.96%;

--Cumulative Expected Losses (% of Original Balance): 6.35%.

CSFB HEAT 2006-2

--$413.3 million class A affirmed at 'AAA' (BL: 39.71, LCR: 3.52);

--$30 million class M-1 affirmed at 'AA+' (BL: 33.22, LCR: 2.94);

--$27.6 million class M-2 affirmed at 'AA+' (BL: 29.18, LCR: 2.58);

--$16.8 million class M-3 affirmed at 'AA' (BL: 26.29, LCR: 2.33);

--$14.4 million class M-4 affirmed at 'AA' (BL: 23.80, LCR: 2.11);

--$13.6 million class M-5 affirmed at 'AA-' (BL: 21.43, LCR: 1.9);

--$12.4 million class M-6 affirmed at 'A+' (BL: 19.23, LCR: 1.7);

--$11.2 million class M-7 affirmed at 'A' (BL: 17.16, LCR: 1.52);

--$10.4 million class M-8 downgraded to 'BBB+' from 'A-' (BL: 15.24, LCR: 1.35);

--$6.4 million class B-1 downgraded to 'BBB' from 'BBB+' (BL: 13.85, LCR: 1.23);

--$6.4 million class B-2 downgraded to 'BB+' from 'BBB' (BL: 12.35, LCR: 1.09);

--$7.2 million class B-3 downgraded to 'BB-' from 'BBB-' (BL: 10.23, LCR: 0.91);

--$6.4 million class B-4 downgraded to 'B+' from 'BB+' (BL: 9.44, LCR: 0.84);

--$4 million class B-5 downgraded to 'B' from 'BB' (BL: 9.12, LCR: 0.81).

Deal Summary

--Originators: Various originators

--60+ day Delinquency: 15.09%

--Realized Losses to date (% of Original Balance): 0.57%;

--Expected Remaining Losses (% of Current Balance): 11.29%;

--Cumulative Expected Losses (% of Original Balance): 9.66%.

CSFB HEAT 2006-3

--$689.7 million class A affirmed at 'AAA' (BL: 37.23, LCR: 4.03);

--$48.3 million class M-1 affirmed at 'AA+' (BL: 30.49, LCR: 3.3);

--$43.4 million class M-2 affirmed at 'AA+' (BL: 26.92, LCR: 2.92);

--$25.9 million class M-3 affirmed at 'AA' (BL: 24.21, LCR: 2.62);

--$22.4 million class M-4 affirmed at 'AA-' (BL: 21.85, LCR: 2.37);

--$22.4 million class M-5 affirmed at 'A+' (BL: 19.49, LCR: 2.11);

--$20.3 million class M-6 affirmed at 'A' (BL: 17.31, LCR: 1.87);

--$18.2 million class M-7 affirmed at 'A-' (BL: 15.29, LCR: 1.66);

--$14.7 million class M-8 affirmed at 'BBB+' (BL: 13.50, LCR: 1.46);

--$7 million class B-1 affirmed at 'BBB' (BL: 12.45, LCR: 1.35);

--$7 million class B-2 affirmed at 'BBB' (BL: 11.42, LCR: 1.24);

--$14 million class B-3 downgraded to 'BB-' from 'BBB-' (BL: 8.70, LCR: 0.94);

--$9.8 million class B-4 downgraded to 'B+' from 'BB+' (BL: 8.11, LCR: 0.88);

--$4.2 million class B-5 downgraded to 'B+' from 'BB' (BL: 8.03, LCR: 0.87).

Deal Summary

--Originators: Wells 43%;

--60+ day Delinquency: 12.12%

--Realized Losses to date (% of Original Balance): 0.41%;

--Expected Remaining Losses (% of Current Balance): 9.23%;

--Cumulative Expected Losses (% of Original Balance): 7.21%.

CSFB HEAT 2006-4

--$786.7 million class A affirmed at 'AAA' (BL: 38.18, LCR: 3.3);

--$56 million class M-1 affirmed at 'AA+' (BL: 31.65, LCR: 2.74);

--$52 million class M-2 affirmed at 'AA+' (BL: 27.74, LCR: 2.4);

--$30.4 million class M-3 affirmed at 'AA' (BL: 24.92, LCR: 2.16);

--$26.4 million class M-4 affirmed at 'AA-' (BL: 22.46, LCR: 1.94);

--$25.6 million class M-5 affirmed at 'A+' (BL: 20.07, LCR: 1.74);

--$23.2 million class M-6 affirmed at 'A' (BL: 17.87, LCR: 1.55);

--$21.6 million class M-7 downgraded to 'BBB+' from 'A-' (BL: 15.76, LCR: 1.36);

--$16 million class M-8 downgraded to 'BBB' from 'BBB+' (BL: 14.19, LCR: 1.23);

--$11.2 million class B-1 downgraded to 'BBB-' from 'BBB' (BL: 12.98, LCR: 1.12);

--$8 million class B-2 downgraded to 'BB+' from 'BBB-' (BL: 11.92, LCR: 1.03);

--$16 million class B-3 downgraded to 'B' from 'BB+' (BL: 9.02, LCR: 0.78);

--$12.8 million class B-4 downgraded to 'B' from 'BB' (BL: 8.73, LCR: 0.76), and removed from Rating Watch Negative.

Deal Summary

--Originators: Wells 33%;

--60+ day Delinquency: 14.47%

--Realized Losses to date (% of Original Balance): 0.47%;

--Expected Remaining Losses (% of Current Balance): 11.56%;

--Cumulative Expected Losses (% of Original Balance): 8.42%.

CSFB HEAT 2006-5

--$476.9 million class A affirmed at 'AAA' (BL: 35.79, LCR: 2.86);

--$31 million class M-1 affirmed at 'AA+' (BL: 29.52, LCR: 2.36);

--$28.7 million class M-2 affirmed at 'AA+' (BL: 26.23, LCR: 2.09);

--$17 million class M-3 affirmed at 'AA' (BL: 23.66, LCR: 1.89);

--$15.5 million class M-4 downgraded to 'A+' from 'AA-' (BL: 21.32, LCR: 1.7);

--$14 million class M-5 downgraded to 'A' from 'A+' (BL: 19.20, LCR: 1.53);

--$13.1 million class M-6 downgraded to 'BBB+' from 'A' (BL: 17.18, LCR: 1.37);

--$12.3 million class M-7 downgraded to 'BBB' from 'A-' (BL: 15.24, LCR: 1.22);

--$10.6 million class M-8 downgraded to 'BB+' from 'BBB+' (BL: 13.38, LCR: 1.07);

--$6.3 million class B-1 downgraded to 'BB' from 'BBB' (BL: 12.09, LCR: 0.97).

Deal Summary

--Originators: Various originators;

--60+ day Delinquency: 14.75%;

--Realized Losses to date (% of Original Balance): 0.29%;

--Expected Remaining Losses (% of Current Balance): 12.52%;

--Cumulative Expected Losses (% of Original Balance): 9.89%.

These transactions were placed on 'Under Analysis' on Aug. 21, 2007. The rating actions are based on changes that Fitch has made to its subprime loss forecasting assumptions. The updated assumptions better capture the deteriorating performance of pools from 2006 and late 2005 with regard to continued poor loan performance and home price weakness. Additional details are available in the following research, also available at www.fitchratings.com:

--'Downgrade Criteria for Recent Vintage U.S. Subprime RMBS' (Aug. 8, 2007);

--'U.S. Subprime RMBS/HEL Upgrade/Downgrade Criteria' (June 12, 2007).

All of Fitch's ratings criteria for US subprime RMBS available at www.fitchratings.com/subprime. For a list of deals currently under analysis please visit www.fitchratings.com/smartview.

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.