Four largest PBMs now control three-quarters of US drug benefit market, AMA finds

The four largest pharmacy benefit managers controlled 75 per cent of the US market in 2024, up from 70 per cent two years earlier, according to a report from the American Medical Association.

The analysis, based on 2024 data from Decision Resources Group on PBMs and prescription drug plans, also found that the share of local PBM markets classed as highly concentrated under federal antitrust thresholds rose from 82 per cent in 2022 to 94 per cent in 2024.

UnitedHealth Group's (UNH) OptumRx and Cigna's (CI) Express Scripts each held 23 per cent of the national market, followed by CVS Health's (CVS) Caremark at 18 per cent and Prime Therapeutics, which is jointly owned by several Blue Cross Blue Shield plans, at 11 per cent. Express Scripts gained the most ground, rising from 17 per cent in 2022, while Caremark lost the most, slipping from 21 per cent.

Vertical integration is also entrenched. Insurers with their own PBMs covered 69 per cent of people across commercial plans and Medicare Part D in 2024, with the share higher in Part D (73 per cent) than in commercial insurance (67 per cent). UnitedHealth was the largest insurer offering drug benefits in both the commercial market (14 per cent) and Medicare Advantage prescription drug plans (30 per cent). Kaiser Permanente ranked second in commercial coverage at 10 per cent, and Humana (HUM) second in Medicare Advantage drug plans at 19 per cent.

The authors said the findings bear on whether proposed or completed mergers among PBMs, and between insurers and PBMs, should raise antitrust concerns. Concentration could lead to higher prices paid by insurers for PBM services, higher premiums, incomplete rebate pass-through and lower reimbursement for pharmacies.