Robert Rubin and Paul O'Neill, former secretaries of the Treasury, said more fiscal stimulus likely won't help, although economic improvement remains slow. Mr. Rubin said another round of stimulus might spur uncertainty and undermine investor confidence. Meanwhile, Mr. O'Neill said companies will refrain from expanding their staffs or facilities until sales improve. "We are moving forward at a pretty gradual pace," he said. "But I don't think things are terrible."