Moderna Inc. (NASDAQ:MRNA) and Merck & Co. (NYSE:MRK) delivered the first positive Phase 3 readout ever for an individualized mRNA cancer therapy. Moderna’s triple-digit stock surge is dominating Wednesday’s tape, but Merck’s stake in that same data may be the more important story for long-term investors.
- MRNA stock is soaring. See the real-time price action here.
A Genuine 50/50 Partnership
Merck and Moderna’s collaboration on intismeran autogene (mRNA-4157/V940) dates to a June 2016 agreement, amended in 2018. Merck paid Moderna a $200 million upfront fee. Moderna led early research, manufacturing and Phase 1/2 trials, including combination work with Keytruda.
In September 2022, Merck exercised its option and paid Moderna an additional $250 million fee, triggering what Moderna calls the “Merck Participation Term.”
Under the arrangement, the two companies split all costs and any profits or losses equally, worldwide, with Moderna handling manufacturing and process development while Merck leads clinical trials.
The Scoreboard
Merck shares are up 10.69% to $149.41, pushing its market cap to roughly $368.6 billion, per Benzinga Pro data — a far smaller percentage move than Moderna’s, but arguably one of Merck’s biggest single-day dollar moves given its size.
Measured in market cap added rather than percentage gained, Merck actually comes out ahead: its market cap rose by roughly $35.6 billion so far on Wednesday, versus Moderna’s roughly $25.7 billion gain.
Merck also walked in with an already-bullish analyst base. Most covering analysts rated it a Buy, with an average price target of $130.00.
Wednesday’s rally pushes Merck just above its own average target and near the Street-high of $150 — a quieter version of the target-blowout playing out much louder in Moderna.
Merck’s Keytruda patent cliff
Keytruda generated around $31.7 billion in 2025, close to half of Merck’s total revenue. Its core U.S. compound patent expires in December 2028, with related patents potentially pushing exclusivity to 2029 and EU protection lasting until 2031.
Merck’s defense to the patent expiration runs on three tracks. The first is reformulation: the subcutaneous Keytruda Qlex, approved September 2025, plus combination patents that could extend exclusivity past 2042.
The second is aggressive M&A diversification away from Keytruda entirely. The third is next-generation combinations that keep pembrolizumab clinically relevant even after patent loss.
Intismeran is the flagship example of that third track. It diversifies Merck’s revenue away from Keytruda while also extending Keytruda’s own commercial life, creating a differentiated, harder-to-generic-ize regimen that biosimilar makers cannot easily replicate.
The Bottom Line
The Phase 3 win offers real-time evidence that one of Merck’s post-2028 hedges is working — likely why MRK is having a record-setting day of its own, even though the economics only give it half the pie.
MRK, MRNA Stock Price Activity: Merck & Co shares were up 10.67% at $149.59, and Moderna stock was up 138.79% at $150.34 at the time of publication Wednesday, according to Benzinga Pro.
Photo: New Africa / Shutterstock
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