Warren Buffett’s Berkshire Hathaway is IBM’s biggest shareholder, and perhaps biggest advocate. But the Oracle of Omaha took it to the teeth Monday when Big Blue’s quarterly earnings spooked Wall Street. Armonk, NY-based IBM revealed third-quarter results that widely trailed expectations on the top and bottom lines, and was forced to abandon hopes it would reach annual per-share earnings of $20 by 2015. Traders panned the results, sending the shares tumbling 7.1%.