So, Merck & Co. (MRK) is writing another big check. On Wednesday, the pharmaceutical giant agreed to buy Terns Pharmaceuticals Inc. (TERN) for about $6.7 billion in cash. That works out to $53 per share for the smaller biotech.

If you're wondering why a company the size of Merck is suddenly so interested in a firm like Terns, you only need to look at the calendar. Merck's golden goose, the cancer immunotherapy drug Keytruda, is staring down a patent cliff that could arrive as soon as 2028. Keytruda isn't just any drug; it brings in roughly $30 billion a year. That's a revenue stream you don't just replace overnight. So, Merck is on a shopping spree, and Terns is the latest addition to the cart.

The Financial Times was first to report the deal.

The Clock is Ticking on Keytruda

This acquisition is a direct move to plug a future hole in Merck's pipeline. The company has been one of the most aggressive dealmakers in biotech lately, and it's easy to see why. When you have a $30-billion-a-year product heading toward generic competition, you get busy.

This isn't Merck's first rodeo in the last year. In 2025, it scooped up Verona Pharma plc for about $10 billion to get its hands on a promising respiratory disease drug. Then, just a few months later in November, it bought influenza drug maker Cidara Therapeutics for another $9.2 billion. Merck is clearly in "fill the pipeline" mode, and it's not being shy about the price tags.

What Merck Is Actually Buying

The crown jewel in the Terns deal is a drug called TERN-701. It's an early-stage treatment for chronic myeloid leukemia (CML), a type of blood and bone marrow cancer. Terns is gearing up to start late-stage clinical trials by late 2026 or early 2027, which means it's a longer-term play for Merck—exactly the kind of bet you make when you're planning for a post-Keytruda world.

The data so far looks promising. In 2025, Terns presented Phase 1 results from its CARDINAL trial at a major hematology conference. The data showed that 64% of previously treated, refractory CML patients achieved a major molecular response within 24 weeks of taking TERN-701. In the world of cancer drug development, that's the kind of signal that gets big pharma's attention.

Is $6.7 Billion Enough?

Here's where it gets interesting. Not everyone thinks Merck is paying full price. Analysts at William Blair published a note on Wednesday suggesting the offer might not fully capture TERN-701's potential.

"TERN-701 is well-positioned to disrupt the treatment paradigm of CML and challenge the dominance of Novartis AG's (NVS) Scemblix franchise," wrote analyst Andy Hsieh.

His point is a classic dealmaking one: if the asset is that good, and the offer leaves some value on the table, someone else might swoop in. Hsieh explicitly noted that the current offer "leaves room for another potential bidder with a more attractive offer." In other words, this might not be the final chapter in the Terns story.

Merck's Deal-Making Appetite

Merck's acquisition push isn't happening in a vacuum. The entire pharmaceutical industry is staring down an estimated $320 billion in revenue losses through 2030 thanks to patent expirations. It's a sector-wide game of musical chairs, and everyone is scrambling for a seat.

Merck's CEO, Rob Davis, has said he generally prefers deals under $15 billion but isn't ruling out bigger moves. That's a telling statement. It means the company is willing to be flexible when it finds something it really wants.

Not every deal works out, of course. Earlier this year, talks between Merck and cancer drug developer Revolution Medicines, Inc. (RVMD) reportedly fell apart after the two sides couldn't agree on a price. Those discussions had involved a potential deal worth a staggering $28 to $32 billion, according to earlier reports. So, while Merck is writing checks, it's not writing blank ones.

The Terns deal is expected to close in the second quarter of 2026. When it does, it will hit Merck's books with a one-time charge of about $5.8 billion, or roughly $2.35 per share. That charge will be reflected in both the second quarter and full-year 2026 results, under both GAAP and non-GAAP accounting.

On the day the news broke, the market reacted positively. Merck shares were up 2.23% at $118.97, while Terns Pharma shares jumped 5.53% to $52.76, according to market data.

So, Merck gets another promising asset for its pipeline. Terns shareholders get a nice premium. But if the analysts are right, this might just be the opening bid in a larger auction. Stay tuned.