The New York Stock Exchange halted the trading pending an announcement. But the company, operator of such well-known stores as Brooks Bros. and Bonwit Teller, made no immediate statement, and the exchange resumed trading in the stock. Allied is the target of a $3.5-billion takeover bid by Canadian developer Campeau Corp. Early last week, Campeau offered to increase its offer for Allied to $66 a share in cash from $58 a share. The sweetened offer, however, was conditioned on Allied's board giving its approval.