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.

Berkshire Hathaway is deploying its $344B cash pile into undervalued stocks like UnitedHealth, while trimming Apple and BAC. See why BRK.A stock is a buy.

If any investor has stood the test of time, it is Warren Buffett, and with good reason. For years, the “Oracle of Omaha” has had a rock-star-like presence in the investing world, and his annual Berkshire Hathaway shareholders meeting draws thousands of loyal fans who are investors.

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.

The investment comes as UnitedHealth faces soaring medical costs, federal investigations, the fallout of the killing of a top executive and a cyberattack last year.

The conglomerate sold Apple shares during the second quarter, though the iPhone maker remains Berkshire’s largest stockholding.

See Berkshire Hathaway Inc.'s strategy with a big new stake in UnitedHealth. Learn how it's hedging against recession and stagflation. Click for my BRK.A update.