Merck & Co., Inc. (NYSE: MRK) stock traded higher on Friday, December 12, 2025, as investors weighed a new European regulatory tailwind for pulmonary arterial hypertension drug WINREVAIR (sotatercept) against a backdrop of policy-driven vaccine headlines, Keytruda-related legal friction in Europe, and a steady stream of Wall Street price-target updates.
As of 17:07 UTC (midday New York trading), MRK shares were at $99.69, up $0.68 (+0.69%) on the session.
Merck stock price: where MRK stands on Dec. 12, 2025
MRK enters the final stretch of 2025 after a solid two-day run earlier in the week. On Thursday, Dec. 11, Merck closed at $99.01 (+1.42%), though it lagged some large-cap pharma peers that day, and it remained 6.45% below its 52-week high of $105.84 (set Nov. 25). [1]
That “near $100” price level matters to investors because it sits at the intersection of two competing narratives:
- A tangible pipeline diversification story (Winrevair expansion, infectious disease dealmaking, respiratory assets)
- A long-term Keytruda concentration risk (patent cliffs, pricing pressure, and now litigation-related hurdles for next-generation formulations)
The headline driver on Dec. 12: EU committee backs broader WINREVAIR use
Merck’s biggest company-specific catalyst today is Europe.
Merck announced that the European Medicines Agency’s CHMP recommended approval of an expanded indication for WINREVAIR (sotatercept) in pulmonary arterial hypertension (PAH, WHO Group 1), alongside other PAH therapies, covering adult patients in WHO Functional Class II, III, and IV. [2]
Why the Winrevair update matters for MRK stock
The expanded EU label would move the conversation beyond “exercise capacity” and more directly toward hard clinical outcomes:
- Merck said the recommendation is based on thesotatercept’s Phase 3 ZENITH study, where adding WINREVAIR to background therapy delivered a 76% reduction in risk for the primary morbidity/mortality endpoint (HR 0.24, p<0.0001). [3]
- In ZENITH, the composite primary endpoint occurred in 17% of WINREVAIR-treated patients vs 55% on placebo, and the trial was stopped early at interim analysis due to “overwhelming efficacy,” with patients offered entry into an open-label follow-up study. [4]
- Merck expects a final European Commission decision in Q1 2026. [5]
For stock investors, a CHMP-positive outcome can be meaningful because it often reduces regulatory uncertainty and can improve confidence in international uptake, especially when paired with outcomes language that supports broader physician adoption and payer discussions.
Keytruda remains the center of the MRK story—and the risks around it are evolving
Even with Winrevair momentum, Merck’s equity thesis still orbits Keytruda, the company’s blockbuster cancer immunotherapy.
1) Pricing pressure is becoming more explicit
Merck has said it expects Keytruda to be selected for U.S. Medicare drug price negotiations in 2026, with new pricing slated to take effect January 1, 2028, under the Inflation Reduction Act framework. Reuters also reported that Keytruda generated $29.48 billion in 2024 sales, representing 46% of Merck revenue—highlighting the scale of the concentration risk. [6]
2) A European legal hurdle hits Merck’s “next-formulation” strategy
A separate (and very market-relevant) development came earlier this month: Merck’s subcutaneous Keytruda rollout in Germany ran into a legal barrier tied to a patent dispute with Halozyme.
Fierce Pharma reported a German court granted a preliminary injunction requiring Merck to halt launch activities for Keytruda SC in Germany, after the court found “imminent infringement” of one of Halozyme’s European patents. Merck said it strongly disagreed and considers Halozyme’s patent invalid, while noting that the intravenous Keytruda remains available. [7]
This matters for MRK stock because next-generation delivery (including under-the-skin administration) is widely viewed as a key lever to defend share and convenience as competition rises later in the decade.
Policy and vaccine headlines: RSV antibody safety review and hepatitis B schedule shift
Merck investors have also had to digest policy-driven healthcare headlines in early December—particularly around immunization.
RSV: FDA safety review of injectable RSV antibodies for infants
The Associated Press reported that the FDA opened a safety review of two injectable RSV antibody drugs for babies and toddlers, including Merck’s Enflonsia and Sanofi’s Beyfortus, describing the review as routine and noting labeling updates could occur if needed. [8]
Reuters, in a separate report, framed the issue as fresh scrutiny of RSV infant therapies, tied to seizure-related concerns raised by vaccine skeptics, while also noting Merck has expressed confidence in its product and that Enflonsia was expected to generate about $250 million in sales next year. [9]
Hepatitis B: Merck criticizes move away from universal newborn birth-dose recommendation
Reuters reported that a U.S. advisory committee voted to scrap its long-standing recommendation for a universal hepatitis B shot at birth, and that Merck—maker of Recombivax HB—said it was “deeply concerned,” arguing the decision puts infants at unnecessary risk. Reuters also noted Merck shares fell about 1% following the vote. [10]
For MRK stock, these developments create a “headline risk” layer: even when they don’t immediately change financial guidance, they can affect sentiment around vaccination policy, demand visibility, and regulatory posture.
Wall Street forecasts for MRK stock: price targets cluster near the low-$100s, with Winrevair as a swing factor
Analyst outlooks for Merck stock remain mixed—but generally constructive—heading into 2026.
Consensus view
- MarketWatch shows an average MRK target price of $107.24 across 27 analyst ratings. [11]
- MarketBeat lists a similar consensus price target near $107.50, with published targets ranging from $85 (low) to $125 (high). [12]
Notable recent target changes (late Nov–Dec 2025)
Several recent updates highlight how investors are increasingly treating Winrevair as the key “variable” that can offset longer-term Keytruda concerns:
- Guggenheim raised its price target to $122 from $104, keeping a Buy rating, citing probability-adjusted revenue upside for Winrevair in additional pulmonary hypertension settings and modeling a multi-billion-dollar opportunity if expansion succeeds. [13]
- HSBC raised its price target to $120 from $100 and reiterated a Buy rating in a 2026 outlook note, arguing the broader pharma group could be positioned to outperform. [14]
- Morgan Stanley raised its price target to $102 from $100 and maintained an Equal Weight rating, noting an expectation that policy overhangs may wane in 2026 and focus could shift back to fundamentals. [15]
Taken together, the research notes point to a market that’s no longer debating whether Merck needs “the next growth engine”—but rather how large Winrevair (and newer respiratory/infectious assets) can become, and how quickly.
Merck’s diversification playbook: dealmaking to reduce dependence on Keytruda
Merck has leaned into acquisitions and business development as a core investor message: build a broader late-stage engine before Keytruda faces heavier pressure later this decade.
Cidara: a $9.2B bet on flu prevention
Reuters reported Merck agreed to acquire Cidara Therapeutics for about $9.2 billion, gaining access to experimental long-acting antiviral CD388, positioned as a potential single-dose, season-long flu protection approach (not a vaccine), with the deal expected to close in Q1 2026. [16]
Merck also told analysts it sees a commercial opportunity exceeding $5 billion for CD388 and expects the deal to be about a $0.30 EPS headwind in the first 12 months post-close as it invests in development and financing. [17]
Why it matters for MRK stock
The market generally rewards large pharma when deals are perceived as:
- Late-stage or de-risked (closer to commercialization)
- Capable of scaling into meaningful revenue
- Strategically aligned with a known patent cliff
But it also penalizes deals that look dilutive without clear timelines—so Merck’s execution over the next several quarters will be crucial.
What to watch next: the near-term MRK catalyst calendar
Here are the clearest “watch items” investors are tracking after today’s headlines:
- European Commission decision on expanded Winrevair use (expected Q1 2026) [18]
- Any FDA/CDC follow-through on RSV infant antibody safety review (label updates or communications could move sentiment quickly) [19]
- Progress and resolution path in the Keytruda SC patent dispute, especially if litigation broadens beyond Germany or affects launch timing across markets [20]
- Cidara acquisition close and CD388 clinical/regulatory milestones as Merck attempts to strengthen its infectious disease growth story [21]
Bottom line for Merck stock on Dec. 12, 2025
Merck stock is trading in a zone where good news needs to be “big enough” to offset structural concerns.
Today’s CHMP-positive Winrevair development is the type of catalyst long-term investors want to see: it strengthens the “post-Keytruda” narrative with clinical outcomes language and a tangible EU timeline. [22]
But Merck’s near-term tape can still be influenced by:
- Policy-driven vaccine headlines and regulatory scrutiny [23]
- Legal challenges that complicate Keytruda’s next-generation strategy [24]
- The market’s ongoing demand for evidence that diversification efforts translate into durable revenue and earnings power [25]
References
1. www.marketwatch.com, 2. www.merck.com, 3. www.merck.com, 4. www.merck.com, 5. www.merck.com, 6. www.reuters.com, 7. www.fiercepharma.com, 8. apnews.com, 9. www.reuters.com, 10. www.reuters.com, 11. www.marketwatch.com, 12. www.marketbeat.com, 13. www.streetinsider.com, 14. www.tipranks.com, 15. www.tipranks.com, 16. www.reuters.com, 17. www.reuters.com, 18. www.merck.com, 19. apnews.com, 20. www.fiercepharma.com, 21. www.reuters.com, 22. www.merck.com, 23. www.reuters.com, 24. www.fiercepharma.com, 25. www.reuters.com
