(Reuters) -Berkshire Hathaway on Wednesday said it has trimmed its huge stake in Apple and shed four common stock holdings, and kept investors guessing on what could be a major new investment by Warren Buffett. In a regulatory filing describing its U.S.-listed stock holdings at the end of 2023, Berkshire said it sold 10 million Apple shares in the fourth quarter, but still owned more than 905 million shares worth about $174 billion. Though Buffett has been driving Berkshire's investment in Apple, the stock sales in the iPhone maker could have been made by one of his portfolio managers T...