significant amounts of stock since the two Utah banking companies agreed in June to merge and Zions' shares have plummeted.

Shares of Zions, the acquirer, have dropped 22% since June 4, a Friday. The $5.9 billion deal was unveiled that Monday. First Security shares, which rose 19% the day the deal was announced, have fallen back to a 12% gain. In part, that reflects the general malaise in bank stocks in a climate of rising interest rates.

"Given the current uncertainty, perhaps recent insider activity could serve as a valuation clue," First Call research analyst Stacey Griffin said in a note to clients.

Between July 20 and Aug. 11, six insiders at First Security sold 103,493 shares, according to disclosure reports filed with the Securities and Exchange Commission and monitored by First Call. In addition, the bank's chairman and chief executive, Spencer F. Eccles, filed a notice to sell 150,000 shares.

At Zions, several insiders have also registered sales. Executive vice president A. Scott Anderson bought 1,000 Zions shares in June at $56.81 per share on the dip following the merger announcement, then sold 10,000 shares on July 30 at $57.88 per share in a transaction valued at $607, 740.

Ms. Griffin said that could put Mr. Anderson in violation of the SEC's "short-swing profit rule," which bars insiders from buying low and selling high in connection with a material event, such as a merger. A Zions spokesman, Dale M. Gibbons, had no immediate comment.

In afternoon activity Tuesday, Zions shares traded at $50.375 while First Security shares were at $22.25.

In July, Zions itself disclosed a sale of 85,000 shares worth $4.98 million by president and chief executive officer Harris H. Simmons, saying the move was tax-related.

Sellers at First Security include its president and chief operating officer, Morgan J. Evans, who disposed of 40,000 shares, chief financial officer Brad D. Hardy, who sold 13,500 shares, and vice president Michael P. Coughlin, who dumped 14,256 shares.

The analyst said the First Security sales were not surprising because some insiders there "likely will not remain at the merged entity."

However, "given that insiders have been selling from both companies and both stocks have come under pressure, their action may be an indication of how they value the deal in the near term," she said.

A spokesman for First Security did not return a call for comment. In all cases, the insiders who sold still retain stakes in their companies. Mr. Eccles and Mr. Simmons will be co-chief executives of the new company, which will be called First Security.

Wall Street analysts, while mostly supportive of Zions, have been cautious on the outlook since the deal was unveiled. "This is a larger deal than Zions has done before," said Thomas Smith, a banking analyst with Standard & Poor's Equity Group.

"There is integration risk for any transaction where you combine two large companies," said industry analyst Michael A. Plodwick of Lehman Brothers.

Besides the merger-risk concerns, the deal was unveiled amid growing concern about higher interest rates. And indeed, the Federal Reserve raised short-term rates on June 30 and again in August. Predictably, bank stock values have suffered.

The merger of Zions and First Security will unite two longtime rivals and create the second largest bank with headquarters in the West, behind Wells Fargo & Co., with $40 billion of assets and a presence in 10 states.

First Call is a unit of Thomson Financial, which also owns American Banker.

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