After spending most of September and early October increasing his cash pile – primarily by selling hundreds of millions of Bank of America (NYSE: BAC) shares – Warren Buffett’s Berkshire Hathaway (NYSE: BRK.A, BRK.B) finally reported a major stock purchase.Specifically, ‘The Oracle of Omaha’ filed a series of buys of Sirius XM Holdings Inc (NASDAQ: SIRI) on October 10 and 11. The billionaire spent approximately $87 million buying about 3.6 million SIRI shares. The average purchase price hovered at roughly $ ...