" Even with today's gain, it is still below that level, making it a losing position for Berkshire, for now.

That could change, however, with Michael Burry, of "Big Short" fame, and Appaloosa Management's David Tepper also revealing Q2 purchases of UNH.

According to CNBC.com, Deutsche Bank analyst George Hill wrote to clients, "The move by Berkshire represents a big vote of confidence in UNH and likely could provide a near-term trading floor for most of the MCO [Managed Care Organization] space and, given Berkshire’s investment track record, could serve as a near-term bottom and rallying point for other investors that the space is safe to invest in again."

Reuters quotes portfolio manager Jeff Jonas as saying he's surprised by the size of UNH's gain, "But that shows how beaten up and out of favor the stock and entire health insurance sector is."

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