For a second year, Berkshire's per-share book value underperformed the S&P 500, but not by much. It was up 10.5 percent vs. the benchmark index's 10.9 percent gain. In his annual letter, Buffett wrote he ""struck out"" on several potential multi-billion dollar acquisitions, on top of finding only a few attractive stocks to buy. As a result, Berkshire ended the year with $43 billion in cash, ""not a happy position."