Warren Buffett, the CEO of Berkshire Hathaway, has built a record cash pile.REUTERS/Rick WilkingWarren Buffett has grown Berkshire Hathaway's cash pile to more than $300 billion — a record high.The famed investor has halted stock buybacks and pared key holdings such as Apple and Bank of America.Buffett, 94, is facing a bargain drought and may be preparing to hand over control of Berkshire.Warren Buffett has been selling shares and stacking up cash at a terrific rate, fanning speculation as to why the world's foremost stock picker is pulling his money out of the market.Berkshire Hathaway roughly tripled its pile of cash, Treasury bills, and other liquid assets to a record $325 billion over the two years to September 30 (or $310 billion after subtracting almost $15 billion of payables for Treasury bill purchases).The conglomerate's cash hoard now exceeds Berkshire's total market value just over a decade ago.