NEW YORK (AP) -- Wall Street finished a turbulent week with another huge drop Friday after major banks warned of further losses on their debt portfolios, raising investor concerns that the credit market slump shows no sign of abating. The Dow Jones industrial average fell more than 220 points.

Bank of America Corp., JPMorgan Chase & Co. and Wachovia Corp. all said the ongoing credit crisis will cause another round of heavy losses during the fourth quarter. Financial institutions took big hits during the last quarter as losses from subprime mortgages hurt their balance sheets.

BofA said continued "market dislocations," including those related to securities it owns that are backed by loans, will affect its fourth-quarter results. The bank did not provide an estimate of how large the impact will be. JPMorgan said difficult conditions may cause a fourth-quarter writedown, but did not say how much.