Berkshire Hathaway lost $11.5 billion. Buffett spent $14.5 billion. And then, he told his shareholders about the two worst decisions he had made along the way. Now, most of us have met a version of this moment. The market is falling. The people who warned you look like prophets. Every instinct says wait until it is over. What Buffett did instead is the whole subject of this letter, and it contradicts nearly everything panic tells you to do.