Pfizer (PFE) has been aggressively pursuing deals and FDA approvals for new products and new indications over the past few years, but all of that has been overshadowed by the runaway success of its COVID-19 product, which has generated tens of billions of dollars in revenue over the past few years.

On Tuesday, the company reported earnings with mixed results. While earnings per share came in higher than expected at $1.08 compared to an expected loss of $0.18, the company fell short of revenue expectations of $14.4 billion, reporting $14.25 billion instead.

Now that revenue spikes from COVID products have been left in the rearview mirror, including a $3.5 billion refund to the U.S. government for unused paclovid treatments, Wall Street is looking for the next big thing from the company.

Pfizer CEO Albert Burla says the next big thing is here, it’s completed with the $43 billion acquisition of Seagen, an oncology company that specializes in antibody-drug conjugate therapies, or ADCs.

ADCs are gaining popularity in oncology because they serve as a less harmful way to treat cancer, delivering chemotherapy in a way that does less damage to healthy cells.

And the platform is already familiar to Pfizer, which launched its first drug, Mylotarg, in 2000. But Pfizer discontinued it in 2010 after a study showed that the dosage used was more toxic than chemotherapy. In 2017, Pfizer managed to bring back a lower dose of the drug for use in cancer patients.

The bet on Seagen, according to analysts, works in Pfizer’s favor in two ways: it gives it a potential new blockbuster (or several) with a pipeline built on a revitalized ADC platform, and it also helps plug numerous holes in revenue due to patent expirations in the second half of the decade.

That’s why Pfizer is furiously signaling Wall Street about all the big and small M&A deals and approvals.

But the company’s shares don’t reflect investor optimism. They’re trading at about $27 a share, well below pre-pandemic levels and down more than 37% over the past year.