Shares of UnitedHealth Group (UNH -4.76%) were pulling back again today on reports that the Senate is working on a bill that would force health insurers like UnitedHealth to divest their pharmacy benefit managers (PBMs) within three years.As a result, the stock was trading down 5% at 11:44 a.m. ET. Other health insurance stocks, including Cigna and CVS Health, were down on the news as well. Regulators are comingThe bill, which was reported by The Wall Street Journal, appears to have bipartisan support, as i ...