The U.S. Department of Labor finalized a sweeping rule requiring pharmacy benefit managers to disclose detailed information about their compensation to self-insured employer clients. The disclosures include rebate structures negotiated with drugmakers and “spread” payments, which represent differences between what PBMs reimburse pharmacies and what plans pay. Regulators estimate the rule could reduce drug costs for employers and workers by $22 billion over a decade. Under the final rule, PBMs must provide the data when negotiating or renewing employer contracts and then again every six months, with employers able to audit disclosures at least annually. The rule is set to take effect in July 2027 and includes potential contract invalidation and financial penalties for noncompliance. While employers and policymakers broadly supported the move, PBMs and industry critics argued the rule could disrupt contracting and business operations. The finalized regulation adds another layer of regulatory scrutiny to PBM economics and may affect how employers structure formulary and contracting terms during the 2027 transition window.