Yahoo has $2.3 billion in cash. Employees have told us they're begging management for some of that stash to buy more machines and hire more engineers. But Legg Mason fund manager Bill Miller — the guy who controls the second-largest collection of Yahoo shares around — told the New York Timesit's time for Yahoo to buy back some stock. "It would be almost incoherent not to do so," Miller said. "You can't maintain that $33 undervalues your company, have your stock trade below that, and not buy back stock." Yahoo shares fell 15 percent to $24.37 by market close today.