Warren Buffett has never been a big technology stock investor. He stuck to companies he understood, and that served him and Berkshire Hathaway (BRKA 0.67%) (BRKB 0.59%) investors well during his 60-year tenure as CEO. But that also led him to fall behind a bit in recent years, by his own admission. "I would say I understand fewer of the businesses as a percentage of the whole than I did 10 years ago," he said in a recent interview. "I have not learned new industries for some years." Nonetheless, he oversaw ...