The Treasury said it is considering lowering the minimum guaranteed rate on savings bonds due to declining interest rates . . . Thrifty Corp. reported that it has completed the acquisition of Guild Inc. and its three subsidiaries . . . GlenFed Inc. stock has begun trading on the Pacific Stock Exchange in addition to its current listing on the New York Stock Exchange . . . Movielab said it has agreed to be acquired by Viacom International in a stock swap with an indicated value of about $14 million . . . Memorex Corp. announced the layoff of 300 workers . . . Jack Eckerd Corp. of Clearwater, Fla., and Merrill Lynch Capital Partners reported the completion of the leveraged buyout of Jack Eckerd by a group of investors led by Merrill Lynch, members of management and the Eckerd employee profit sharing plan.