Warren Buffett finally reveals the mysterious company he's invested $10 billion in

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. Berkshire revealed it acquired nearly 26 million shares of Chubb in yesterday's Securities and Exchange Commission filing of the company's first-quarter investments. That translates to a value of approximately $6.7 billion ($AUD10 billion). Buffett's company had shielded the position from public knowledge as it was building the stake, requesting "confidential treatment" …