The U.S. Department of Labor finalized a rule requiring pharmacy benefit managers to disclose detailed information about compensation to self-insured employer clients. Regulators estimate the policy could reduce drug costs by $22 billion over a decade, while PBMs argue the rule increases administrative burden and threatens contracting stability. The disclosure package includes rebates negotiated with drugmakers and “spread” payments—fees PBMs keep when they reimburse pharmacies at a lower rate than the plan pays. The rule takes effect July 2027, requires disclosures during contract negotiations or renewals, and mandates updates every six months, with annual employer audit rights. PBMs face potential financial penalties and contract invalidation for noncompliance, signaling a major shift in how plan sponsors can evaluate PBM pricing behavior.