For the past five years, whenever DEC shares have been hanging heavy on a market maker’s books after a slide in profits or other negative news, said broker puts about a rumour that the Maynard minimaker is about to get a bid from AT&T Co – and it works dammit, every time: happened again on Monday when the rumour did the Wall Street rounds and DEC shares put on $3.125 to $90.25 in heavy trading – and was enough believed that AT&T shares fell 25 cents to 27.375, the usual reaction in the shares of a firm making, or tipped to make, a bid.