UnitedHealth Got a Boost From Berkshire’s Buying. 2 Reasons to Wait to Follow. UnitedHealth Group, the worst-performing stock in the Dow Jones Industrial Average so far this year, got a major boost last week from billionaire investor Warren Buffett. That doesn’t mean everyone else should buy.

Warren Buffett's Berkshire Hathaway built a $1.6 billion stake in UnitedHealth last quarter, marking one of its last wagers with the investor as CEO.

Berkshire Hathaway’s $1 billion homebuilding investment indicates Warren Buffett’s confidence in a future U.S. housing market rebound.

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.

Warren Buffett is known for seeking out stocks of companies that possess wide economic moats — businesses with durable competitive advantages that fend off rivals and ensure long-term profitability. These moats,

UNH stock soared after Warren Buffett’s Berkshire Hathaway revealed it bought shares of the healthcare company. Nonetheless, UnitedHealth faces a long list of unresolved issues.

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