Berkshire Hathaway disclosed significant portfolio changes in its first quarter under new CEO Greg Abel, including a $2.6 billion investment in Delta Air Lines that marks the conglomerate's return to airline investments.

The Warren Buffett-led company increased its stake in Alphabet while completely exiting its position in Amazon, according to regulatory filings. Berkshire also sold holdings in UnitedHealth Group, Visa, and Mastercard during the quarter.

The Delta investment represents a notable shift back into the airline sector for Berkshire, which had previously held airline stocks before selling them during the COVID-19 pandemic's early stages. The $2.6 billion stake signals renewed confidence in the aviation industry's recovery prospects.

Berkshire also acquired a position in Macy's as part of broader portfolio reshuffling during Abel's first quarter as chief executive. Abel took over from Buffett as CEO while the 94-year-old investor remains chairman and continues to oversee investment decisions.

The moves come as Berkshire continues managing its massive equity portfolio, with the company typically making strategic adjustments based on long-term value assessments. The exits from technology and healthcare positions alongside the airline re-entry reflect evolving views on sector prospects and valuations.