Merck & Co., Inc. (NYSE: MRK) finished regular trading on Wednesday, Dec. 17, 2025 in positive territory, then held near the $99 level in extended hours as investors weighed two major pipeline headlines—one before the opening bell and another after the close—alongside a renewed policy backdrop around U.S. drug pricing. Investing.com+1
Below is what moved MRK today, what the late-breaking after-hours news could mean, and what to keep on your radar before U.S. markets open Thursday, Dec. 18.
Merck stock recap: where MRK stands after the bell (Dec. 17)
Merck shares closed at $99.18 on Dec. 17, up 0.93% on the day after trading between roughly $98.13 and $100.10. Investing.com
In after-hours trading, MRK was still around $99.18 as of the latest available print (7:33 p.m. ET / 00:33 UTC), suggesting the market’s initial reaction to the post-close catalyst was relatively muted—at least early in the evening session.
That calm tape matters, because one of today’s most market-relevant developments hit after the closing bell.
The after-hours catalyst: FDA “National Priority Voucher” fast-tracks two Merck experimental drugs
After the market closed, Reuters reported—citing internal documents—that the U.S. FDA is preparing to fast-track reviews for two experimental Merck programs under the Commissioner’s National Priority Voucher pilot, a pathway intended to compress review timelines to roughly one to two months versus typical cycles. Reuters
1) Enlicitide decanoate: a potential first-in-class oral PCSK9 inhibitor
According to the Reuters report, Merck’s enlicitide decanoate (a cholesterol-lowering pill) is expected to be filed in April 2026 and could become the first oral PCSK9 inhibitor, putting it into direct competitive proximity with injectable PCSK9 drugs such as Amgen’s Repatha. Reuters also noted Merck has publicly projected multibillion-dollar peak annual sales potential. Reuters
Why investors care: cardiometabolic innovation remains one of the biggest “rotation” arenas in biopharma capital allocation right now, and a credible oral entrant in a major lipid-lowering class can reshape how the street models long-term growth beyond Merck’s current mega-franchises.
2) Sacituzumab tirumotecan (sac‑TMT): an oncology ADC with blockbuster ambitions
Reuters also reported the FDA expects a filing for sac‑TMT in late 2026 (October/November 2026) and highlighted Merck’s $700 million development funding deal with Blackstone Life Sciences. Jefferies analysts cited by Reuters said the structure of that Blackstone deal implied potential peak annual sales above $10 billion. Reuters
Why investors care: antibody-drug conjugates (ADCs) are a core battleground in oncology R&D—and a credible, high-ceiling ADC asset can materially affect how investors handicap Merck’s post‑Keytruda revenue bridge.
The key takeaway from the voucher story
Even if MRK’s tape was quiet in early after-hours, the strategic implication is straightforward: FDA review speed is a lever. Shorter review windows can tighten the gap between filing and potential commercialization, which is exactly the kind of timeline compression investors look for when a company is trying to diversify ahead of major patent cycles.
The premarket catalyst: Keytruda + Padcev posts another Phase 3 win in earlier-stage bladder cancer
Before U.S. markets opened Wednesday, Merck announced positive topline results from a Phase 3 study of Keytruda (pembrolizumab) + Padcev (enfortumab vedotin) in cisplatin-eligible muscle-invasive bladder cancer (MIBC). Merck said the combination significantly improved event-free survival (EFS) and key secondary endpoints including overall survival (OS) and pathologic complete response (pCR) when given before and after surgery compared with standard neoadjuvant chemotherapy and surgery. Merck.com+2Pfizer+2
Astellas and Pfizer (partners on Padcev) emphasized that the regimen is positioned as a platinum-free perioperative approach and said the data will be presented at an upcoming medical meeting and discussed with regulators for potential filings. Pfizer+1
Independent clinical coverage echoed the topline message: the trial met primary and key secondary endpoints, with the safety profile described as consistent with known profiles and no new safety signals highlighted in early summaries. OncLive+1
Why the Keytruda‑Padcev readout matters to MRK stock
For Merck investors, the significance is less about a single headline and more about the direction of travel:
- Earlier-stage oncology expansion tends to be commercially meaningful because it can increase duration of therapy and total addressable population over time.
- The Keytruda‑Padcev pairing continues to build a body of evidence across stages of bladder cancer; the combination already had regulatory momentum in MIBC settings, and today’s readout strengthens the argument for broader perioperative use. Pfizer+1
The bigger MRK narrative: pipeline urgency as Keytruda approaches biosimilar competition
Reuters framed the FDA voucher development explicitly in the context of Merck’s push to advance new programs before Keytruda—described as the world’s top-selling drug with nearly $30 billion in annual sales—faces cheaper biosimilar competition later this decade. Reuters
That backdrop is why the market often responds disproportionately to “de-risking” moments (late-stage wins, accelerated regulatory pathways, funding partnerships that validate asset value, etc.). Today delivered multiple such signals.
Policy watch: MFN drug pricing talks are back in focus—and Merck is still in discussions
A second Reuters report on Dec. 17 said several large pharmaceutical companies are nearing agreements with the U.S. government related to most-favored-nation (MFN) drug pricing initiatives, with an announcement anticipated as soon as Friday. The report said Merck is among companies still in discussions. Reuters+1
Why this matters overnight: while the market may not have immediate specifics on Merck’s exposure, policy headlines can shift sector multiples quickly—especially if investors conclude that pricing frameworks could affect U.S. profitability for major commercial franchises.
MRK stock forecast: what “the Street” is signaling right now
Forecasts are mixed—typical for a mega-cap pharma balancing blockbuster cash flow with long-term transition risk.
- MarketBeat lists a consensus “Hold” rating (based on 17 analysts) and an average 12‑month price target of $108, with estimates ranging from $85 to $125. MarketBeat
- TradingView’s aggregated analyst range shows estimates from roughly $82 (low) to $139 (high). TradingView
Read that as: analysts broadly see Merck as investable, but the dispersion reflects real debate over (1) the pace of pipeline monetization and (2) how the post‑Keytruda era gets priced.
Quick technical pulse heading into Thursday
If you track technicals alongside fundamentals, Investing.com’s snapshot shows:
- Moving averages leaning bullish (multiple “buy” signals across common MAs),
- Overall daily indicators closer to neutral,
- RSI in the low‑to‑mid 50s, often interpreted as neither overbought nor oversold territory. Investing.com
This isn’t a prediction—but it helps frame why tomorrow’s move may depend more on news digestion and macro prints than on an obviously stretched chart.
What to know before the stock market opens Thursday, Dec. 18
Here are the practical checkpoints MRK traders and longer-term investors will likely focus on premarket:
1) Watch whether the FDA voucher story changes tone in premarket
The Reuters voucher headline hit after the close. Premarket trading will show whether institutions decide it’s a “real catalyst” (higher bids, stronger volume) or mostly a longer-dated pipeline story that doesn’t change near-term cash flows. Reuters
2) Look for follow-up details on Keytruda + Padcev
Today’s bladder-cancer readout was topline. The next level of scrutiny usually includes:
- hazard ratios, absolute EFS/OS deltas, subgroup consistency,
- discontinuation rates and safety specifics in perioperative settings,
- what regulators signal about filing strategy and label ambition. Pfizer+1
Any incremental details (or analyst notes reacting to them) can influence Thursday’s open.
3) Macro data could set the tape before 9:30 a.m. ET
Thursday morning is unusually important for premarket risk sentiment because the Consumer Price Index (CPI) for November 2025 is scheduled for 8:30 a.m. ET—and it’s being released under unusual circumstances after a major U.S. government shutdown disrupted the October CPI collection. BLS has warned the report will have gaps and certain one-month changes will be unavailable where October data are missing. Bureau of Labor Statistics+2Bureau of Labo…
Alongside CPI, traders also often monitor weekly jobless claims and the Philadelphia Fed manufacturing reading on Thursdays, which can amplify index volatility into the open. Econoday
Why this matters for MRK specifically: Merck is often treated as a “defensive” healthcare name, but on CPI mornings, correlations frequently rise across the tape—meaning MRK can move with broader market risk-on/risk-off even if company news is stable.
4) Policy headlines into Friday: MFN deal watch
With Reuters reporting a potential announcement on Friday regarding MFN-related agreements, any Thursday leaks, confirmations, or denials can move large-cap pharma as a group (and MRK with it). Reuters
Bottom line for Merck stock heading into Dec. 18
Merck goes into Thursday with a rare alignment of catalysts:
- Near-term sentiment support from another Phase 3 “win” for Keytruda + Padcev in earlier-stage bladder cancer, reinforcing oncology franchise durability. Merck.com+2Pfizer+2
- Longer-term narrative support from a post-close Reuters report that two experimental Merck drugs could receive accelerated FDA review under the Commissioner’s National Priority Voucher pathway—exactly the kind of speed advantage that can matter when investors are modeling the post‑Keytruda transition. Reuters
- A real policy overhang as MFN-related drug pricing agreements remain in motion and Merck is reportedly still in discussions. Reuters
- A high-impact macro morning, with November CPI due at 8:30 a.m. ET under shutdown-affected conditions—an important context setter for the entire market before the bell. Bureau of Labor Statistics+1
