A Deal With Novo Nordisk Sent This Stock 181% Higher Overnight. Is It a Buy Now?

Shares of Omeros (NASDAQ: OMER) finished Oct. 14's trading session at $4.10 per share. When the market opened on Oct. 15, the stock was up by 181% at $11.52 per share.

It was a deal with the Danish drugmaker that markets Ozempic and Wegovy that moved Omeros' stock price. Novo Nordisk (NYSE: NVO) will give the clinical-stage drugmaker $340 million upfront for exclusive global rights to develop and commercialize zaltenibart. This is the experimental complement system inhibitor formerly known as OMS906.

As a company without any product sales, Omeros' deal with Novo Nordisk is significant. That said, there are no guarantees this chronic loss recording company will be able to make ends meet down the road. Here's a closer look at recent developments to see if it's a good stock to buy now.

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Reasons to buy Omeros stock now

If zaltenibart succeeds in clinical trials, earns approval, and becomes a successful commercial-stage product, Omeros is eligible to receive up to $2.1 billion in milestone payments from Novo Nordisk. Despite the big run-up, Omeros' market cap at midday on Oct. 15 was just under $700 million. That seems like a very low valuation for a company about to receive $340 million in cash.

Zaltenibart, which targets a protein called MASP-3, is not the most advanced new drug candidate in Omeros' development pipeline. The company's lead candidate, narsoplimab, is an experimental MASP-2 inhibitor with an application currently under review by the Food and Drug Administration (FDA).

Omeros is developing narsoplimab for the treatment of stem cell transplant-associated thrombotic microangiopathy (HSCT-TMA). The FDA issued a complete response letter to the company in 2021 regarding its first application to treat HSCT-TMA. According to Omeros, the agency had difficulty estimating the treatment effect and asked for additional data.

Last December, Omeros provided more data regarding narsoplimab and HSCT-TMA patients, and the FDA is taking a second look. The agency was expected to announce its decision by Sept. 25, 2025. In August, the FDA pushed the date we can expect a decision announcement back to Dec. 26, 2025.

Omeros signaled a licensing deal for OMS906 could be coming soon when it reported second-quarter results in August. At the time, management said an upcoming deal for zaltenibart was the most advanced of multiple asset sale discussions.

Reasons to be cautious about Omeros' stock now

When the FDA said it wanted more data in 2021, the agency most likely wanted the company to run a new study with a randomized control group. Instead, Omeros compared the overall survival data from 28 patients it treated with narsoplimab in the OMS721-TMA-001 study against a group of similar patients who were not enrolled in the trial.

While the HSCT-TMA results Omeros sent the FDA made narsoplimab appear effective, I'll be very surprised if the agency approves an application supported by data from an external control group.

Unfortunately, approval to treat stem cell transplant recipients could be narsoplimab's last chance to become a commercial-stage drug. In 2023, it failed to reduce signs of kidney damage for patients with a different autoimmune disorder in a pivotal trial.

Omeros finished June with just $28.7 million in cash and short-term investments after burning through $58.9 million during the first half of 2025. A cash injection from Novo Nordisk will help it pay down some debts and keep the lights on for over a year.

With narsoplimab's future highly uncertain, nearly all of Omeros' value is tied up in zaltenibart. While there's a chance it could succeed in a phase 3 trial and lead to a huge milestone payment from Novo Nordisk, this is a heavy risk most investors should not feel comfortable with. If your risk tolerance level isn't sky high, it's probably best to leave this stock on a watch list instead of in a portfolio.

Cory Renauer has no position in any of the stocks mentioned. The Motley Fool recommends Novo Nordisk. The Motley Fool has a disclosure policy.