Bank stocks have recently been so volatile that some market watchers wonder if they have at last topped out and are signaling an approaching bear market.

The mercurial price behavior "is typical of late-cycle activity," suggesting a stalling bull market, said William Raftery, a technical equity analyst with Salomon Smith Barney.

"People want to get in quickly, but they are just as fast to pull the trigger," believing the gains by banks cannot be sustained, Mr. Raftery said.

The market itself has been highly changeable in recent weeks. But shares of financial institutions have swung far more dramatically than the overall market, rising higher on up days and then falling further in the aftermath.

Just last week, for example, the Standard & Poor's bank index jumped 1.82% one day, then dropped back 1.20% the next. Over the same two days the less-erratic S&P 500 gained 1.06% and shed just 0.23%. About-faces by individual banks can be even more dramatic.

"There is no sustainable steam," Mr. Raftery said. "Banks appear to be getting tired." In coming months, banks "may give up the cushion" that the long bull market has provided, he said.

The adjustment could be even more dramatic if bonds become more favorably priced, Mr. Raftery said.

There is no denying that banks, instead of moving steadily forward as they did without much break from 1995 through 1997, appear to be "taking a breather" said James M. Schutz, a banking analyst at ABN Amro.

The development is not surprising, given those prior years of "very solid, uninterrupted increases in bank stock prices," he said.

The last break occurred back in the fourth quarter of 1994, he said. At the time, interest rates were rising sharply.

The impact of a slowdown on individual banks will vary, depending on the size of the institution, the analyst said. Big banks are now performing in line with the market, but could see additional gains on renewed takeover activity. Smaller banks, left out of the merger whirl so far, could become the pacesetters as consolidation becomes more commonplace within their group, he said.

Still, no one is predicting an immediate meltdown for bank stocks. Indeed, banks have long been market mavericks, moving differently than the rest of the market, said Catherine Murray, a banking analyst with J.P. Morgan Securities.

For instance, shares of financial institutions tend to rise in the weeks before earnings are released, while other stocks react more in line with announcements, Ms. Murray said.

Banks stand to fare even better because their double-digit earnings growth seems more sustainable than advances by other industries, she said.

Higher-profile, more-expensive stock are likely to see the first selling by investors hunkering down for a bear market, said William R. Katz, a banking analyst at Merrill Lynch & Co.

Friday's stock activity offered more uncertainty, as some banks dipped while broader markets gained. The Standard & Poor's bank index added 0.33% and the Dow Jones industrial average 0.10%. The Nasdaq bank index shed 0.25%, and the S&P 500 was up 0.23%.

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