Prepayment speeds on lower coupon, unseasoned conventional issues accelerated faster than expected. At the same time, older vintages and premium speeds held flat or slowed inline with expectations.
In the Fannie Mae sector, 2002 6s jumped nearly 20% to 26% CPR, while 2001 issues were up 10% to 44% CPR. In 6.5s, 2002 vintages gained 7% to 45% CPR; 2001 issues held flat. Lastly, in the 7% sector, 2002s rose 3% to 45% CPR, while older vintages slowed 1% to 2% CPR.