Berkshire Hathaway's $1.6 billion stake in UnitedHealth Group is helping to lift the Dow Jones Industrial Average to a new record as investors pile into healthcare sector funds.

The company may be under criminal investigation for alleged irregularities in its Medicare business—but it’s been touched by the Warren Buffett effect. Shares in the troubled private health insurer UnitedHealth Group (NYSE: UNH) are currently seeing their best trading day in months.

Shares of some of UnitedHealth’s peers got a bump in the wake of Berkshire’s investment in the healthcare giant, and they all look cheaper based on price relative to expected earnings.