In an SEC Form 4 filing this evening, Berkshire Hathaway reported that it added $64 million to its stake in Phillips 66 (NYSE: PSX) on May 19, 20 and 23 at approximately $77.50 – $78.50 per share. Berkshire Hathaway now owns 76.4 million shares of PSX, representing 14.5% of its outstanding shares. This is the first PSX purchase Berkshire has made in three months. Berkshire’s PSX investment is valued at $5.9 billion at today’s closing price on the New York Stock Exchange of $77.82. Previously, Warren Buffett had disclosed that PSX was his investment and not that of his portfolio managers Todd Combs and Ted Weschler.