The top Democrat and Republican on a powerful Senate committee launched a wide-ranging investigation into private equity's impact on the U.S. health care system on Wednesday. Democratic Sen. Sheldon Whitehouse of Rhode Island and Republican Sen. Charles Grassley of Iowa sent letters to a constellation of financial firms seeking information about how their dealings in the healthcare space impact patient care.

"The American people deserve to understand the role that PE [private equity] firms play — and any potential resulting negative financial or patient care impacts — in the delivery of their health care," wrote the senators, who lead the Senate Budget Committee. READ MORE