Billionaire Warren Buffett‘s Berkshire Hathaway Inc (NYSE:BRK) (NYSE:BRK) surprised many observers by offloading a significant portion of Berkshire’s Apple Inc (NASDAQ:AAPL) holdings in the second quarter. Berkshire Hathaway’s balance sheet is now substantially weighted to United States treasury bills. The Data: According to Berkshire’s most recent filing, the Omaha, Nebraska-based company now owns $234 billion in treasury bills. That’s more than the Federal Reserve’s $195 billion treasury bill war chest. The U.S. central bank has gradually wound down its balance sheet in recent years. It is a…