SYRACUSE, N.Y. -- Penn Traffic Co. here said its board of directors has authorized the repurchase of up to 500,000 shares of its common stock, either on the open market or through private transactions. The 269-store company has approximately 10.8 million shares outstanding. A Wall Street securities analyst said Penn Traffic's buy-back disclosure was made about six weeks prior to the release in late November of the chain's third-quarter results. "[Those results] could be below expectations," he said. "If that's the case, then the company may be looking to buy back stock at lower price levels, which may be the reason it's making this announcement now."