Call option volume surged in

American Express

(AXP) - Get Report

as chatter flooded the market that the credit card giant might get taken over, market pros said.

As shares of American Express rose $1.53 to $49.02, the prices of the options also rose as demand for the options jumped.

Options volume was heaviest in American Express' out-of-the-money February 50 calls, where buyers of the options hopped into the market en masse. Total volume in the February 50 calls reached 13,500 by midday and was heaviest on the American Express options, where more than 5,300 of the February 50 calls traded.

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Open interest (the number of contracts in existence) stood at a little more than 7,400 as of Thursday's close. Because the volume in the February 50 calls outstrips the open interest total, it indicates that Friday's positions are fresh money and not simply investors closing out already established positions.

The price of the February 50 calls rose 1.05 ($105) to 1.60 ($160) on the Amex. The kind of price and volume action is the kind of aggressive speculation that comes when traders are expecting big news out of a company.

Implied volatility, the market's estimate of how much the underlying security can move, has surged. Paul Foster of

1010WallStreet.com

in Chicago said implied volatility in the February 50 calls surged to 49 today from 39.

While the options action is aggressive, American Express would be a difficult takeover target especially because of its size -- a market capitalization stands at roughly $65 billion.

A spokesman for American Express said the company has a long-standing policy not to comment on market speculation or rumors.