Merck Stock’s New Drugs Were Already Answering The Big Question

While Wall Street fretted over the future of its biggest blockbuster, a pair of new drugs were already showing the company’s next act was well underway.

For years, the question hanging over Merck (MRK) was simple and difficult: what happens after KEYTRUDA? When a single drug becomes the engine of a pharma giant, investors rightly worry about the patent cliff on the other side. So when Merck stock took off on a +50.3% run starting on Jun 17, 2025, the market was reacting to the company’s answer, which was already showing up in the numbers, hidden in plain sight.

The real story was being written at the cash register. The evidence was building that Merck’s plan to diversify away from its blockbuster cancer drug was now a reality.

How Fast Were The New Drugs Ramping Up?

Two new launches, in particular, were telling the tale. WINREVAIR, a treatment for pulmonary arterial hypertension, saw its sales build with textbook momentum. It booked $149 million, grew to $200 million, and then hit $280 million. That’s not a slow trickle; it’s the sound of a successful launch finding its market.

It wasn’t alone. The pneumococcal vaccine CAPVAXIVE (referred to by another name in an earnings call) went from an “encouraging start” to posting $50 million in sales, then more than doubling to $107 million. These weren’t rounding errors. They were the first tangible returns on a significant pipeline investment.

What Was Management Saying About This Pipeline?

You didn’t have to read tea leaves. On its earnings call on April 24, 2025, management was explicit, framing these as just the beginning. An executive noted that WINREVAIR and CAPVAXIVE were the “initial launches from this robust pipeline of 20 promising potential new growth drivers.” The company had been repeating this theme for months, pointing to a late-phase pipeline with a “potential commercial opportunity of over $50 billion by the mid-2030s.”

The difference was that by April 24, 2025, this was no longer just a PowerPoint slide. The early revenue from these new products was proof of concept for the entire strategy.

Why Wasn’t This Signal Louder?

To be fair, the signal was hardly screaming. The company’s overall top-line growth had actually slowed. As of its fiscal Q1 2025 report, Merck’s trailing twelve-month revenue growth was 4.1%, a deceleration. If you only looked at the headline number, you might have missed the engine revving underneath. The growth in the new portfolio was being masked by the scale of the legacy business.

The numbers for the new launches provided the first hard evidence that Merck could, in fact, successfully navigate the KEYTRUDA patent cliff.

Can You See A Run Like This Coming?

Some of it, yes. The single most visible pre-surge signal is a company guiding its own forecasts higher, and you do not have to hunt for those one call at a time. Our Guidance Momentum rankings list the names raising guidance with the price already moving with them. One signal is never the whole story, though. The Trefis High Quality (HQ) Portfolio weighs the full range of quality signals across thousands of names, owns the 30 strongest, sizes and re-balances them with discipline, and has outpaced a benchmark that combines the major indices – the S&P 500, S&P Mid-cap, and Russell 2000.