Warren Buffett and Greg Abel walkthrough the Berkshire Hathaway Annual Shareholders Meeting in Omaha, Nebraska on May 3, 2025. David A. Grogen | CNBC Berkshire Hathaway's revamp of its portfolio sent certain stocks higher in early trading Monday, while others slipped as investors parsed the company's latest bets and exits disclosed in the conglomerate's quarterly filings.The Omaha-based conglomerate published its quarterly U.S. stock portfolio on Friday, under new CEO Greg Abel, who took the helm at the start of the year from legendary investor Warren Buffett. The latest filing showed that Berkshire purchased 39.8 million shares in Delta Airlines, valued at $2.6 billion, making it the company's 14th largest holding by the end of March. Delta was last up 2.5% in premarket trading. This comes after Buffett sold Berkshire's entire billion-dollar portfolio of U.S. airlines during the Covid-19 pandemic, including Southwest, American, United, and Delta due to changed consumer travel behaviour. Google parent Alphabet saw the biggest investment of 58 million shares, up 224%, making it Berkshire's seventh largest holding. The tech giant was down 0.6% in early trading Monday. Other moves included a new stake in Macy's, a 35% reduction in Chevron, including selling $8 billion worth of shares, and selling Mastercard and Visa. Macy's was last up 5% in premarket trading, while Chevron, Mastercard and Visa were trading just below the flatline. Meanwhile, Berkshire completely exited its investment in Amazon, selling 2.3 million shares in the first quarter, which was all that remained after it sold 7.7 million of its 10 million share holding in the fourth quarter. Amazon was down 0.7% in premarket. Some of the moves are likely related to efforts to unwind positions tied to former investment manager Todd Combs, who left the company at the end of 2025 to join JPMorgan. Combs had been personally recruited by Buffett to manage Berkshire's equity portfolio, alongside Ted Weschler, who still oversses 6% of the holdings. Abel previously revealed that he continues to consult 95-year-old Buffett on investment decisions. watch now"He's in the office every day, so we're talking every day if I'm in Omaha, we're always connecting," Abel told CNBC's "Squawk Box" in March. "If I'm traveling, like I was yesterday, I often check in just to catch up on what he's seeing, what he's hearing, what am I feeling. So if it's not every day, it's every couple days."— Yun Li and Alex Crippen contributed to this report