Omeros Corporation (NASDAQ: OMER) is ending Christmas Eve 2025 as one of the market’s most volatile and news-driven movers after the U.S. Food and Drug Administration approved the company’s first commercial product — a moment investors have waited years to see.
As of 2:35 p.m. ET in after-hours trading on Wednesday, Dec. 24, 2025, OMER stock traded around $15.36, up about $6.59 (+75%) from the prior close, after swinging through a wide intraday range on heavy volume.
This move matters not only because it’s dramatic — it’s because it’s tied to a hard catalyst: FDA approval of YARTEMLEA (narsoplimab‑wuug) for a rare, often life-threatening post-transplant complication. [1]
OMER stock after-hours: the key numbers from today’s holiday-shortened session
U.S. equities and options markets closed early at 1:00 p.m. ET on Dec. 24, 2025 and are closed Thursday, Dec. 25 (Christmas Day). That means there is no “market open tomorrow” for Nasdaq-listed Omeros; the next regular session is Friday, Dec. 26, 2025. [2]
Here’s what stands out in OMER’s tape after the bell:
- After-hours price (as of 2:35 p.m. ET): ~$15.36
- Day’s range: roughly $9.05 to $17.55 (a massive spread that signals “event trading,” not normal drift)
- Volume: about 24.45 million shares, far above typical activity for the name
- Multiple outlets reported trading halts/pauses around the news and volatility, which is common when a small/mid-cap biotech gaps sharply on material announcements. [3]
Because this happened during a holiday-shortened session, investors should assume liquidity is thinner than usual in both after-hours and the next premarket, which can exaggerate moves in either direction.
What happened today: FDA approval turns Omeros into a commercial biotech
The catalyst is straightforward: the FDA approved YARTEMLEA (narsoplimab‑wuug) for the treatment of hematopoietic stem cell transplant–associated thrombotic microangiopathy (TA‑TMA) in adults and children ages 2 years and older. [4]
TA‑TMA is a severe complication that can develop after stem cell transplantation; it involves blood-vessel injury and clotting that can lead to organ damage (often the kidneys) and can be fatal. [5]
Importantly for the investment narrative, this is not Omeros’ first trip to the FDA with this asset. Reuters notes the FDA previously declined to approve the drug in 2021, citing insufficient evidence at the time, making today’s decision a major reversal and a removal of a long-standing overhang. [6]
Why the approval is a bigger deal than “just another biotech headline”
Several factors are driving the market’s reaction:
1) “First and only” positioning in a high-acuity setting
Omeros is emphasizing that YARTEMLEA is the only FDA-approved therapy indicated for TA‑TMA — a strong commercial positioning statement in a rare-disease, urgent-care context. [7]
Reuters also highlights that while other drugs may be used off-label in practice, there wasn’t a dedicated FDA-approved option for TA‑TMA before this approval. [8]
2) A differentiated mechanism (lectin pathway / MASP-2)
YARTEMLEA works by selectively inhibiting MASP‑2 in the lectin pathway of complement, which multiple reports frame as a “first” for this indication. [9]
In plain English: investors are now looking at Omeros as having converted a long-running clinical story into a marketable, mechanism-based therapy.
Today’s clinical and safety snapshot investors are focusing on
Omeros and third-party coverage repeatedly point to a relatively consistent set of efficacy markers supporting approval:
- Complete response (CR):61% in the pivotal study (n=28 adults) [10]
- CR:68% among evaluable patients in the expanded access program (EAP) [11]
- 100-day survival: about 73%–74% across the study/EAP populations [12]
On safety and operational friction, today’s coverage also includes several details traders will keep revisiting:
- Serious infections occurred in 36% of patients in clinical trials (a meaningful risk factor in a transplant population). [13]
- Omeros states no boxed warning and no REMS are required, and vaccinations are not required prior to treatment — notable because some complement drugs come with vaccination requirements. [14]
These points matter because “commercial success” in rare disease is often driven by: urgency + clarity of benefit + logistical simplicity.
What Omeros says comes next: launch timing and the next big date to circle
Omeros says it is finalizing preparations for a U.S. launch planned for January 2026. [15]
Additional near-term milestones and details mentioned in today’s reporting include:
- Dedicated billing and reimbursement codes are described as already in place in some coverage, a key commercialization lever for hospitals and transplant centers. [16]
- A patient support program (“YARTEMLEAssist”) is expected in Q1 2026, according to Investing.com’s report. [17]
- Omeros will host a conference call Monday, Dec. 29, 2025 at 4:30 p.m. ET to discuss the approval. [18]
- A European Medicines Agency review is ongoing, with a decision expected mid‑2026. [19]
That Dec. 29 call is especially important: when a biotech gaps up on approval, investors typically listen for first concrete answers on pricing, initial demand signals, distribution, and cash runway.
Today’s analyst reaction and price targets: what the Street is saying right now
The approval triggered same-day commentary and reiterations from multiple shops and market commentators:
- Reuters quoted H.C. Wainwright’s Brandon Folkes, noting Omeros had become a “show-me” story — and that the FDA decision removes a major overhang and refocuses attention on value and pipeline. [20]
- A TheFly/TipRanks note said D. Boral Capital maintained a Buy rating with a $36 price target, framing the approval as a shift from development-stage to commercial-stage and highlighting the “sole provider” angle. [21]
- GuruFocus summarized H.C. Wainwright maintaining a Buy rating with a $20 price target, and referenced a model assumption of roughly $150,000 treatment cost per patient (an estimate, not confirmed pricing). [22]
- A Seeking Alpha analysis estimated peak revenue potential around ~$300 million (author estimate) and argued for longer-term upside if commercialization executes. [23]
One caution for readers: price targets and revenue models released or circulated today vary widely and are inherently assumption-driven. But the common thread is clear — the approval changed the debate from “will it be approved?” to “how big can the launch be, and how quickly?”
Options flow and short interest: why OMER could stay extremely volatile into Friday
Two market-structure forces can amplify biotech moves after a binary event:
Unusual call option activity
MarketBeat reported 29,728 call options traded, roughly 579% above typical daily call volume, suggesting aggressive positioning or hedging around the approval-driven move. [24]
Options volume doesn’t automatically mean “smart money is bullish” — it can also reflect market makers hedging, funds covering shorts with calls, or traders betting on a post-approval continuation move. But it does flag elevated speculative interest.
Elevated short interest (potential fuel — but not a guarantee)
Multiple trackers show Omeros with meaningful short interest as of the latest reporting periods (generally in the high-teens to low-20% of float, depending on the source and methodology). [25]
In a name that just jumped this hard, that can matter because:
- Shorts may reduce exposure (cover), adding buy pressure.
- Longs may press the move, expecting squeeze dynamics.
- Volatility can spike as both sides reposition, especially around holidays when liquidity is thinner.
What to know before the “next open” (Friday, Dec. 26, 2025)
Since U.S. equity markets are closed Thursday, Dec. 25, the next actionable window for many traders is Friday morning premarket and the regular session open on Dec. 26. [26]
Here’s a practical watchlist for OMER stock into that next session:
1) After-hours price stability vs. continued whipsaws
Today’s move was big enough that many market participants will look for:
- whether OMER holds above key psychological levels (e.g., mid-teens), or
- fades back toward the gap zone created today.
Holiday after-hours can be thin; treat prints as directional, not definitive.
2) Any follow-up filings, FDA label details, or company commentary
The market will be sensitive to anything that clarifies:
- dosing and safety language beyond headlines,
- distribution logistics (specialty pharmacy / hospital channel),
- post-marketing commitments (if any are discussed publicly),
- launch readiness (inventory, access programs, field team).
3) Pricing and reimbursement signals
Reuters noted Omeros did not immediately provide pricing in response to inquiry. [27]
That’s one of the most important “unknowns” because TA‑TMA is rare but high-acuity; pricing will influence revenue potential, payer pushback risk, and hospital adoption.
4) Guidance on cash, runway, and potential financing strategy
This is not specific to Omeros — it’s a biotech pattern: after a major spike, investors often watch for potential capital raises. Even if nothing is announced, commentary on cash needs can move sentiment quickly.
5) The Dec. 29 conference call (the next scheduled catalyst)
If you’re tracking OMER beyond Friday’s open, the Monday, Dec. 29, 4:30 p.m. ET call is the next hard timestamp where management may give more specifics on launch and expectations. [28]
Bottom line for Omeros stock after the bell on Dec. 24, 2025
Omeros stock is reacting to a fundamental step-change: FDA approval of YARTEMLEA, the company’s first approved product and the first therapy indicated for TA‑TMA. [29]
Between the holiday-shortened tape, after-hours liquidity, high options activity, and elevated short interest, investors should expect continued volatility into the next session on Friday, Dec. 26 — with attention quickly shifting from “approval headline” to launch execution, pricing, and early adoption signals. [30]
This article is for informational purposes only and is not investment advice.
References
1. www.reuters.com, 2. www.nasdaqtrader.com, 3. news.bloomberglaw.com, 4. www.reuters.com, 5. www.reuters.com, 6. www.reuters.com, 7. investor.omeros.com, 8. www.reuters.com, 9. investor.omeros.com, 10. investor.omeros.com, 11. investor.omeros.com, 12. investor.omeros.com, 13. investor.omeros.com, 14. investor.omeros.com, 15. investor.omeros.com, 16. www.investing.com, 17. www.investing.com, 18. investor.omeros.com, 19. www.reuters.com, 20. www.reuters.com, 21. www.tipranks.com, 22. www.gurufocus.com, 23. seekingalpha.com, 24. www.marketbeat.com, 25. www.marketbeat.com, 26. www.nasdaqtrader.com, 27. www.reuters.com, 28. investor.omeros.com, 29. www.reuters.com, 30. www.nasdaqtrader.com
