Berkshire Hathaway, Buffett’s investment group, disclosed it had bought 5 million shares of the healthcare company earlier in the year. That sparked a 14% Friday rally in a stock that has lost more than half of its value over the past 12 months.

Shares of UnitedHealth Group are surging before the market open Friday as Warren Buffett’s Berkshire Hathaway disclosed that it recently purchased shares of the beleaguered insurer

The Oracle of Omaha just took a $1.6 billion stake in the battered healthcare giant, sending shares soaring 9% after hours.