B&C News Briefs ÆSerious delinquencies on outstanding subprime mortgages notched upward in September. According to data compiled by research firm LoanPerformance, some 6.96 percent of subprime loans were at least 90-days past due at the end of the third quarter, up from 6.91 percent in the second quarter. Despite the upturn, delinquencies were well below the 7.38 percent level reached in March, and they hovered about 15 basis points lower than they were last September,