Financial Winners & Losers: KeyCorp - TheStreet

KeyCorp's

(KEY) - Get Report

expectation of higher loan charge-offs sent bank stocks tumbling Wednesday, as investors worried whether other lenders will face the same fate.

Key shares plunged 10.4% to $19.66 after the regional bank announced that it expects net loan charge-offs to be closer to 1% to 1.3%, instead of its earlier forecast of 0.65% to 0.90%. Homebuilders unable to pay back loans were the culprit behind the damaging debt.

Other regional banks also dipped on the news.

Regions Financial

(RF) - Get Report

fell 5% to $18.08.

Fifth Third Bancorp

(FITB) - Get Report

slid 3.6% to $18.85, after the stock hit a 52-week low of $18.48 during the day's trading.

The

NYSE

Financial Sector Index slid 15.42 to 7,296.02.

Elsewhere, private banking firm

Boston Private Financial Holdings

(BPFH) - Get Report

sunk 7% to $8.48 after it said it was reviewing its capital levels and may have to raise more money.

Just days away from its meeting in which shareholders are expected to approve its sale to

JPMorgan Chase

(JPM) - Get Report

,

Bear Stearns

( BSC) fell 0.9% to $9.38.

Bond insurer

Ambac Financial

( ABK) plummeted 9% to $2.94 after confessing that it too would take more charges as a result of its writedowns on credit derivatives in April. Net writedowns on its credit derivatives holdings totaled $176 million, with the insurer taking a writedown of $228 million on the value of collateralized debt obligations.

Insurance giant

American International Group

(AIG) - Get Report

fell after a Citigroup analyst suggested its recent plans to raise capital may not be enough. Shares gave back 4.7% to trade at $34.91.

One of the few winners for the day was

Commerce Bancshares

(CBSH) - Get Report

, which saw shares jump 3.5% to $44.07 after Standard & Poor's announced that the Kansas City-based bank will join the S&P MidCap 400 index after the close of trading June 5.