The Trump administration wants pharmacy benefit managers (PBMs) to open their books on how they set drug prices. In January, the Department of Labor rolled out a proposed rule forcing PBMs to share detailed pricing data with employers and submit to audits. Firms will have to spell out rebates, fees and spread pricing arrangements. Employers, who ultimately foot the bill for many prescriptions, would see exactly how much of their payment ends up in PBM pockets. More than 500 comment letters flooded in before last week’s deadline. PBMs and major health insurers slammed the proposal, warning it would expose confidential contracts and undermine negotiations. They argue that revealing rebate details could drive up list prices and reduce competition. On the other side, Mark Cuban’s Cost Plus Pharmacy and several business groups cheered the move. They say transparency would curb hidden markups and give employers leverage to demand better deals. Drugmakers took a mixed stance. Many applauded the effort to rein in PBMs, who they blame for distorting true drug costs. But they pushed back on the breadth of data disclosures, fearing competitors could use that information to undercut pricing strategies. Some pharmaceutical lobbyists suggested narrowing the rule to focus solely on administrative fees and excluding rebate data tied directly to specific drugs. With the comment period now closed, the Labor Department will review feedback before finalizing the rule. If enacted, it could reshape the drug supply chain by shifting power toward employers and away from intermediaries. PBMs could face tighter scrutiny on every dollar they collect. Employers, for their part, would gain clarity but could also grapple with complex data streams when negotiating future contracts.