IRA Drug Pricing: Reshaping Biotech Valuations

Everyone focuses on the science. The money is in the policy.

The Inflation Reduction Act’s Medicare Drug Price Negotiation Program is the biggest structural change to biotech economics since the Hatch-Waxman Act created the generic drug pathway in 1984. For the first time, the federal government can negotiate what Medicare pays for top-selling drugs. The first 10 negotiated prices took effect in January 2026 with an average discount of 22% from net prices, according to CMS data analyzed by KFF. The second round of 15 drugs will take effect in 2027 with an estimated 44% savings. The third round, announced for 2028, brings physician-administered Part B drugs into the negotiation fold for the first time and includes Merck’s Keytruda and Bristol Myers Squibb’s Opdivo. The market is not pricing this correctly, and the mispricing is concentrated in a handful of companies that most biotech investors already hold.

The negotiation timeline is the key structural feature. Small-molecule drugs become eligible nine years after FDA approval. Biologics get 13 years. This four-year gap is the “pill penalty” and it is already reshaping which drug modalities get funded. A small-molecule drug that would have had 15-plus years of monopoly pricing now faces a price cut in year nine. A biologic faces the same cut in year 13. The difference in net present value is substantial: a drug that loses 40% to 60% of its Medicare revenue in year nine versus year 15 changes the DCF model by hundreds of millions to billions of dollars depending on the drug’s peak sales. The Congressional Budget Office estimates negotiated prices will reduce net prices for selected drugs by roughly 50% on average and projects the program will reduce the number of new drugs reaching the US market by approximately one over the 2023 to 2032 period, five over the subsequent decade, and seven over the decade after that. For context, the FDA approved 55 novel drugs in 2023 alone. The CBO estimate of one fewer drug over a decade is within the rounding error of annual approval variability. The innovation impact is real but small relative to the savings.

The orphan drug exemption is the most misunderstood provision for biotech investors. Single-indication orphan drugs are exempt from negotiation. Multi-indication orphan drugs are not. Here is the catch: CMS aggregates drugs with the same active ingredient, so if a drug has one orphan indication and one non-orphan indication, the entire active moiety loses the exemption. This is the orphan drug pricing policy tension playing out in real time: the exemption protects ultra-rare single-indication products but leaves rare disease drugs with $1B+ peak sales exposed once they expand into larger indications. The small biotech exemption, which shields companies where a single drug represents 80% or more of their Part B or Part D spending and the drug accounts for 1% or less of total Medicare drug spending, is only in effect for the 2026 through 2028 negotiation cycles. After 2028, small biotech drugs face the same negotiation risk as large pharma products.

The exposure matrix is what matters for portfolio construction. Merck (MRK) at $130.92 and $317.6 billion market cap is the most concentrated large-cap IRA risk. Keytruda, a biologic with $3.5 billion in Medicare Part B spending and 13 years post-approval, is selected for the 2028 negotiation round. Januvia, a small-molecule diabetes drug, is already in the first negotiation round at a negotiated price of $113, down 79% from its $527 list price. Janumet is in the second round for 2027. Merck’s IRA exposure spans all three negotiation rounds, and Keytruda alone represents roughly 40% of Merck’s total revenue. The bull case is that Keytruda faces biosimilar competition in 2028 regardless of negotiation, so the IRA price cut is not the primary threat to the franchise; the patent cliff is.

Bristol Myers Squibb (BMY) at $64.84 and $132.2 billion market cap has Eliquis in the first negotiation round. Eliquis was the single largest Medicare Part D drug by spending at $16.5 billion annually. The negotiated price of $231 represents a 56% discount from the $521 list price. BMY also has Opdivo selected for the 2028 Part B negotiation round. This is a compounded exposure: BMY is already feeling the IRA impact on its largest drug while a second top product enters negotiation in two years. The market knows this: BMY trades at 2.6 times sales and 9 times forward earnings, a discount to the large-cap pharma peer group that reflects the patent cliff and IRA overhang.

Eli Lilly (LLY) at $1,231.94 and $1.06 trillion market cap is the test case for whether the IRA actually changes stock prices. Jardiance, co-marketed with Boehringer Ingelheim, is in the first negotiation round. Trulicity is selected for 2028. Together, these two diabetes drugs accounted for $12 billion in Medicare spending in the selection years. But Lilly is a $1 trillion company driven by tirzepatide and the obesity pipeline, not by diabetes drug pricing. The IRA may trim a few billion from Lilly’s revenue curve. The obesity thesis has not changed. At Lilly’s scale, the IRA is a pricing headwind, not a thesis breaker.

Novo Nordisk (NVO) at $47.73 is the single most exposed company to the round two negotiations. Ozempic, Rybelsus, and Wegovy were selected for 2027 with $14.4 billion in combined Medicare Part D spending. This is the largest single-drug selection in the program’s history by spending. The negotiated prices for the GLP-1 franchise have not yet been announced, but the 44% average savings from the round two negotiations provides a benchmark. If Novo’s GLP-1 franchise sees a 40% to 50% net price reduction in Medicare, the impact on total revenue depends on the Medicare mix. The commercial market is not subject to negotiation, and GLP-1s have significant commercial and cash-pay exposure. The IRA is a material headwind for Novo but not an existential one.

The investment playbook is straightforward but requires active screening. First, favor biologics-heavy pipelines over small-molecule-heavy ones for long-term holds. The four additional years of pricing power before negotiation eligibility are real money. Second, favor rare disease and gene therapy for policy insulation. Single-indication orphan drugs are exempt, and one-time gene therapies have no long-term revenue stream to negotiate regardless. Third, screen for Medicare exposure as a percentage of total revenue before buying any large-cap biotech. A company with 60% Medicare exposure and multiple drugs in the negotiation queue is a different risk profile than a company with 15% Medicare exposure and biologics-only pipeline. This is not academic: the first 40 drugs selected for negotiation accounted for $125 billion, or 36% of total Medicare drug spending in 2024. The program is systematically targeting the largest revenue pools.

The legal challenges add uncertainty that cuts both ways. Seven pharmaceutical manufacturers and two trade associations have filed lawsuits challenging the IRA’s constitutionality. The cases argue the negotiation program amounts to an unconstitutional taking, that the guidance should have been promulgated as a legislative rule rather than guidance, and that the orphan drug exclusion is being interpreted too narrowly by CMS. At least one case is expected to reach the Supreme Court. If the program is struck down, the negotiated prices are unwound and the revenue curves revert to pre-IRA expectations. If upheld, the program expands to 20 drugs per year starting in 2029 and the revenue impact compounds. The uncertainty itself is a market inefficiency: investors cannot price a binary Supreme Court outcome, so they default to assuming the program survives.

The IRA is not priced into most biotech portfolios because it is a slow-moving structural change, not an earnings miss or a clinical trial failure. The average biotech investor screens for PDUFA dates and Phase 3 readouts, not Medicare negotiation eligibility dates. That is the opportunity. The companies that screen worst on IRA exposure are the same large-cap names that dominate biotech ETFs and institutional portfolios. If you hold MRK, BMY, or PFE, you hold concentrated IRA risk whether you have thought about it or not. The biotech valuation framework that relies on DCF models with 15-year monopoly pricing assumptions needs a year-nine haircut for every small-molecule drug in the portfolio and a year-13 haircut for every biologic. Most sell-side models have not updated their terminal value assumptions to reflect the new negotiation timeline. The market will catch up. It always does.

The contrarian take is that the IRA creates as many opportunities as it destroys. If the “pill penalty” deters investment in small-molecule development, the companies that continue developing small molecules despite the headwind face less competition. If biologics pipelines attract disproportionate capital, the biologics field becomes crowded and returns compress. The market overcorrects, as markets do. The real alpha is in screening for companies where the market has over-discounted the IRA risk, not in avoiding IRA-exposed names entirely. The best biotech stocks catalyst ranking already applies this lens: the top-ranked catalysts are weighted toward biologics and gene therapies not because small molecules are bad science but because the economic incentives have shifted. Follow the incentives. They are louder than the headlines.