The U.S. Department of Labor finalized a sweeping rule requiring pharmacy benefit managers (PBMs) to disclose extensive compensation information to self-insured employer clients. Regulators expect the policy to reduce drug costs by $22 billion over a decade. The rule, set to take effect July 2027, requires PBMs to share data including rebate arrangements negotiated with drugmakers and “spread” payments—where plan reimbursement exceeds PBM reimbursement to pharmacies. Disclosures must occur when contracts are negotiated or renewed and then every six months, with employers able to audit once per year. The final rule also sets potential consequences for noncompliance, including financial penalties and contract invalidation risk. PBMs have signaled opposition, while employer groups and policymakers have framed the policy as a transparency lever to improve contract negotiation and limit opaque fee structures.