The Gap said a suit was filed against the company, its directors and officers charging that securities laws were violated in connection with the recent nose dive in the price of the company's stock. The San Bruno, Calif., specialty retailer said the suit was without merit. Gap's stock price fell to $37 last Monday on news of a sales slump. A month earlier, when the stock was trading in the mid-$70s, Gap Chief Financial Officer Alan E. Zimtbaum sold 3,000 shares of stock. Zimtbaum said he did not use inside information to profit on the stock trade.