Washington, DC – In a letter sent to Aetna’s CEO today, Senators Elizabeth Warren (D-Mass.), Bernie Sanders (I-Vt.), Edward J. Markey (D-Mass.), Sherrod Brown (D-Ohio), and Bill Nelson (D-Fla.) raised questions about the company’s decision to withdraw from the federal Affordable Care Act (ACA) health care exchanges after the Department of Justice (DOJ) challenged Aetna’s proposed merger with Humana.