TheStreet. Warren Buffett is arguably the most successful investor of all time. He's amassed an amazingly massive net worth by buying and usually holding stocks for the long haul. Trained under legendary value fund investor Benjamin Graham,

Berkshire Hathaway's Q2 2025 portfolio sees changes with new stakes, position trims, and notable increases. Read here for more insights.

Buffett & Co. picked up UnitedHealth stock on the cheap, with the embattled blue chip one of the newest holdings in the Berkshire Hathaway equity portfolio.

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UnitedHealth shares clocked the largest one-day percent increase since March 2020, as tracked by Dow Jones Market Data Group. It was on pace for the best day in 17 years before giving back some of those gains. For the week, shares rose over 21%, the best week since May 2009. Still, the stock is down more than 50% over the past 12 months.

Given Buffett's concern over the stock market, it makes sense for investors to buy the most conservative stocks in the Berkshire Hathaway portfolio.

However, Buffett has a keen eye for value and he never wants to overpay for a stock -- not even his own. Berkshire is currently trading at a price-to-sales ratio (P/S) of 2.5, which is a huge 25% premium to its 10-year average of 2.