Berkshire purchases often boost stocks. Shares of the steel maker traded as high as $151.32 on Friday, but closed at $145.48, up 0.8%. The S&P 500 fell 0.3%. The Dow Jones Industrial Average rose 0.1%.

Key Takeaways Warren Buffett's Berkshire Hathaway increased its holdings in UnitedHealth Group stock.A regulatory filing showed Berkshire held 5 million shares in the second quarter.Berkshire also added positions in D.

Berkshire Hathaway revealed four new investments Thursday in steelmaker Nucor, insurer UnitedHealth and two of the nation’s biggest homebuilders.