The Dow Jones Industrial Average ended nearly flat on Friday after hitting a record high in morning action — riding a wave of market optimism and a timely push from the “Oracle of Omaha.”

In late 2016, Warren Buffett started what would become the most profitable investment in his legendary career. Through his company, Berkshire Hathaway Corp. (BRK.A), he began accumulating shares in Apple Inc.

The big surprise was a brand new, $1.6 billion stake in UnitedHealth, accumulated entirely during the second quarter.

Berkshire Hathaway revealed four new investments Thursday in steelmaker Nucor, insurer UnitedHealth and two of the nation’s biggest homebuilders — Lennar and DR Horton — but only one of the investment

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.

It’s that one decision Buffett says you can’t afford to ignore. Integrity is such a non-negotiable aspect of Warren Buffett’s business practice that he vows the key to success is to associate only with people who possess it. He once said:

Super investors like Buffett and Michael Bury piled heavily into UnitedHealthcare in Q2, signalling confidence that the sector's business model

I told MarketWatch readers on Aug. 14 that Warren Buffett was about to reveal one big mystery elephant for Berkshire Hathaway’s portfolio — one $5 billion investment in the shares of an industrial giant.