Following an investment by Warren Buffett's Berkshire Hathaway, many eyes are on the healthcare insurer these days.

UnitedHealth was a star stock late last week, when it was revealed that Warren Buffett's Berkshire Hathaway had taken a $1.6 billion stake in the company's equity. On Monday, lingering positive sentiment on UnitedHealth was boosted by that price target bump.

UNH stock soared after Warren Buffett’s Berkshire Hathaway revealed it bought shares of the healthcare company. Nonetheless, UnitedHealth faces a long list of unresolved issues.

The company may be under criminal investigation for alleged irregularities in its Medicare business—but it's been touched by the Warren Buffett effect.

UnitedHealth Group ( UNH 12.04%) has been a solid dividend growth stock for years. Generally, its yield has been fairly low, due to the stock's rising value. Even as the healthcare insurance giant has grown its dividend, its yield hasn't been particularly high or noteworthy.

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Year to date, the stock has fallen by nearly 45%, which is by no means normal for the healthcare stock. In fact, this is the worst it has performed since the Great Recession, when it tumbled by more than 54% in 2008.