TheStreet. On May 2, the day before Warren Buffett said he would retire at the end of 2025, Berkshire Hathaway shares hit a record. And then the stocks tumbled, about 14.5% for each class, just about every day until early August.

UnitedHealth Group stock has been rallying on news that Berkshire Hathaway has invested in the business. Warren Buffett is the CEO of Berkshire Hathaway and the investment could be seen as a possible vote of confidence in UnitedHealth's business.

Berkshire Hathaway’s portfolio added six new stocks, including the three new secret stocks. Warren Buffett was a net seller of stocks for the eleventh straight quarter.

Warren Buffett's Berkshire Hathaway has acquired 5 million shares in UnitedHealth Group , a regulatory filing showed on Thursday, sending the health insurer's stock up 7% in extended trading.

Like Amazon CEO Andy Jassy, keeping a positive attitude helps the Warren Buffett-backed leader stay motivated toward success.

A hallmark of Berkshire Hathaway is its focus on long-term value investing, a strategy championed by Warren Buffett and his late partner Charlie Munger. The approach has delivered remarkable returns to Berkshire shareholders, with average annual growth far outperforming the broader stock market for decades.

Berkshire Hathaway recently filed its second-quarter 13F form, revealing its stock holdings at the end of June.