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

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%.

UnitedHealth shares surged Friday after Warren Buffett’s Berkshire Hathaway revealed a stake in the embattled healthcare giant. Monitor these major chart levels.

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

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Leveraged positions in the stock market jumped 18% in one month and topped $1 trillion for the first time. Increasing use of debt to invest can tell us a lot about investors' attitudes. And while this has always been the case,