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.

Warren Buffett secret stock purchase has been kept confidential for months to avoid triggering copycat trades.

Also notice that although these are six brand-new positions, they add up to about $4 billion, significantly less than the proceeds from the Apple, Bank of America, and T-Mobile sales, which is how Berkshire was still a net seller of stocks for the quarter.

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