Warren Buffett's Berkshire Hathaway built a $1.6 billion stake in UnitedHealth last quarter, marking one of its last wagers with the investor as CEO.

Berkshire Hathaway has built up sizable investments in a handful of companies, according to a filing released on Thursday.

Detective work points to one stunning conclusion. Buy the stock or an industrial-sector ETF — but get ahead of Berkshire Hathaway’s big reveal.

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

I would like to receive updates and special offers from Dow Jones and affiliates. I can unsubscribe at any time.

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,