Warren Buffett has cashed in a net $177 billion of stocks because he expects a downturn and plans to capitalize, Wedbush's Paul Dietrich said.

Berkshire Hathaway ( BRK.A -0.05%) ( BRK.B 0.24%) is considered by many to be a reliable stock for long-term investors. It's outperformed the S&P 500 ever since a young Warren Buffett took over the company in 1965, and its evolution from an aging textile maker to a diversified conglomerate churned out millionaire-making gains.

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 emphasizes that while achieving success is exciting, effectively correcting mistakes when they occur is equally critical for businesses.

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

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.

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

Buffett owned UnitedHealth shares before selling his stake in 2010, though his Berkshire Hathaway recently acquired shares.