Buffett's Berkshire Hathaway Inc. this week revealed it has amassed nearly 980,000 shares in WellPoint Inc., the Indianapolis-based health benefits firm, according to Reuters.
Berkshire's stake is worth about $82 million.
Shares of companies often rise after Berkshire discloses investment in them. Buffett, the second-richest man in America, looks for stable, straightforward, industry-leading companies whose shares appear to be undervalued.
Berkshire also reported higher stakes in two other companies in health care, Johnson & Johnson and France's Sanofi-Aventis.