The credit ratings of Stockton, Calif., were slashed yesterday by two Wall Street credit agencies because the city plans to file for bankruptcy soon, Reuters reported yesterday. Standard & Poor's downgraded Stockton to default from selective default yesterday, citing expectations that the city will not pay "substantially" all of its obligations as they come due. Moody's Investors Service cut Stockton's pension obligation debt to Caa3 from B3 and its lease revenue debt to Caa3 from Caa1. "The city is running out of cash and faces limited time and options to fix its structural imbalance," Moody's said yesterday.