Just before bank stocks emerged from a four-week slump last week, options players jumped aboard, eager to ride the wave of good fortune.

The volume of "call" options to buy stocks of BankBoston Corp., BankAmerica Corp., and NationsBank Corp. surged dramatically the week before positive economic news flooded in, lifting the S&P 500 almost 5% and the bank stocks 6.8% in the five trading days through Thursday.

Observers said that options players-who purchase the right but not the obligation to buy a stock at a later date-moved into the stocks to lock in gains before interest rate jitters overtake the market again.

"Investors are jumping on the bandwagon ... to see if they can get further gains from these interest rate sensitive stocks," said Joseph Sunderman, a research analyst at the Investment Research Institute, Cincinnati.

"With better than expected economic reports," he added, "investors are trying to get more exposure to banking stocks, so we're seeing increased volume."

The institute said daily volume in calls to buy BankAmerica shares rose from below 100 before last week to 1,345 last Monday. Call options in shares of NationsBank jumped from 809 on April 17 to 8,905. Volume in options on shares of BankBoston jumped from 979 April 17 to 2,078 Monday.

Volume gradually slipped back to the usual level by Thursday, the institute said.

"Most of the option activity indicates that people are expecting more upside to the stocks, and looking to take advantage of it by adding calls," Mr. Sunderman said. With economic news beating expectations, he noted, traders were betting that banking stocks would jump sharply.

He said options traders had been waiting for the beginning of last week's data before jumping into the market.

The options traders probably would move out of banks, he said, as the Federal Reserve's May 20 monetary policy meeting approaches. A three-week holding period is typical for the option player, who tends to be a "momentum" investor, Mr. Sunderman said.

"I think you have a recognition that the prior selloff was exaggerated," said analyst Michael Mayo of Credit Suisse First Boston Inc. He said banks' share buyback programs and decent first-quarter earnings reports had fueled the rally.

Mr. Mayo said some investors were waiting until the Fed is done raising rates but that others who were in bank stocks in 1994, the last time the central bank raised interest rates more than 200 basis points, have returned to the stocks once again.

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