Warren Buffett has proven again why he is America’s most astute investor. The billionaire’s Berkshire Hathaway on Friday moved to capitalize on a rejuvenated Bank of America — and in the process pocketed a tidy $12 billion profit on its nearly six-year old investment. Here’s how Buffett did it. In August 2011, with many on Wall Street concerned that BofA didn’t have sufficient capital and with its shares in a swift retreat — they were down 30 percent in the first three weeks of the month — Buffett stepped forward with a $5 billion investment in the bank’s preferred shares. The shares paid a dividend of 6 percent, or ... (full story)