The mystery is over: Warren Buffett's Berkshire Hathaway disclosed a major stake in the insurance company Chubb, finally revealing the investment he has kept under wraps since last year.
Buffett's company had shielded the position from public knowledge as it was building the stake, requesting "confidential treatment" from the SEC in previous filings. Buffett, Berkshire's CEO famous for his investing prowess, has amassed a sizable following of investors who mimic his portfolio moves. The investment in Chubb underscores Berkshire Hathaway's investment strategy over the past several months.