Merck (MRK) stock price rises as Enflonsia approval and insider filing keep attention on what’s next
6 February 2026

Merck (MRK) stock price rises as Enflonsia approval and insider filing keep attention on what’s next

New York, February 6, 2026, 11:57 EST — Regular session

  • Merck shares rose nearly 2% in midday trade, extending a multi-day climb.
  • Health Canada cleared Merck’s RSV preventive ENFLONSIA for newborns and infants.
  • Investors are watching an FDA action date later this month tied to Keytruda.

Merck & Co. shares rose 1.8% to $121.92 on Friday, after trading as high as $122.65 earlier in the session. The stock had opened at $121.01.

The move came with a broad rebound across U.S. equities and healthcare, a pocket that tends to draw bids when risk appetite gets shaky. The SPDR S&P 500 ETF gained about 1.5% and the Health Care Select Sector SPDR was up about the same in midday trading.

Merck’s shares were also in focus a day after the company said Health Canada approved ENFLONSIA (clesrovimab) to help prevent RSV lower respiratory tract disease in newborns and infants. ENFLONSIA is a monoclonal antibody — a lab-made antibody shot — designed to provide protection for up to five months, Merck said. “The approval of ENFLONSIA adds a new option for RSV prevention in infants,” Matthew Thornhill, executive director of the vaccines business unit at Merck Canada, said in the release, which also noted availability could vary by province and depend on reimbursement. newswire.ca

Separately, a Form 144 filing dated Feb. 5 showed Chirfi Guindo, listed as an officer, disclosed a proposed sale of 20,000 Merck shares with an aggregate market value of about $2.44 million. Form 144 is a notice tied to SEC Rule 144 for planned sales of restricted or control securities, and it does not confirm a trade was executed.

Merck ended Thursday up 1.2% at $119.75, notching a sixth straight session of gains, even as the broader market fell. Johnson & Johnson rose 1.4% on the day, while Pfizer slipped and Eli Lilly dropped sharply, MarketWatch data showed.

Investors have been weighing how Merck builds growth as older medicines lose patent protection — “loss of exclusivity,” the point when lower-cost copies can enter and pressure prices. Earlier this week, Merck forecast 2026 sales and profit below expectations as it pointed to hits from generic competition, Medicare price negotiations and weaker demand for some products, Reuters reported. Reuters

On RSV, Merck’s shot enters a market where Sanofi and AstraZeneca already sell Beyfortus for infants, and ordering and dosing logistics matter for pediatric practices. When the FDA cleared Merck’s RSV antibody last year, Jefferies analyst Akash Tewari called the single-dose approach “beneficial” because it can simplify planning around infant weight, Reuters reported. Reuters

Analyst tweaks are also circling. Guggenheim raised its price target on Merck to $140 from $122 and kept a buy rating, MT Newswires reported.

But the setup cuts both ways. Merck has pushed toward new highs quickly, and any hint that RSV rollout is slower than hoped — or that pricing and reimbursement turn messy — could test that run, especially if the wider market loses its footing again.

The next near-term catalyst on traders’ calendars is an FDA decision date of Feb. 20 for a Keytruda supplemental filing in platinum-resistant recurrent ovarian cancer, according to an FDA calendar maintained by RTTNews. (That deadline is often referred to as a PDUFA date, after the U.S. user-fee law that sets review timelines.

Khadija Saeed

Khadija Saeed is a financial markets reporter at TS2.tech. Her coverage ranges from stocks and technology to emerging industries and developments across global markets. She studied economics and finance at the London School of Economics and worked in market research before becoming a financial journalist. Follow Khadija Saeed on Google News.

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