Each quarter, all fund managers with at least $100 million in assets under management must publicly disclose their stock holdings to the SEC. Earlier this week, hedge funds disclosed their positions, giving investors insights in which sectors they were active. Warren Buffett's Berkshire Hathaway is one of the most scrutinized. The biggest changes of its portfolio include: the selling of Charter Communications, Merck & Co, AbbVie, Bristol-Myers Squibb, Marsh & McLennan, US Bancorp and the acquisition of Chevron, Royalty Pharma, Floor & Decor Holdings and Liberty Sirius XM Group.