Responding to market speculation, National City says it has experienced no unusual depositor or creditor activity Monday.

The Cleveland-based regional bank says it has more than $12 billion in excess short-term liquidity.

Investors have been worried about the solvency of some banks amid the sharp downturn in the mortgage market. National City Corp. has been among those hit hardest by rising mortgage defaults. It recently raised $7 billion in cash to shore up its capital base.

The bank says the recent capital raise has helped it to maintain a strong capital ratio.

Shares of National City plunged $1.27, or 29 percent, to $3.15 before trading was halted.