If you invest in biotech stocks, PDUFA dates are the single most important dates on your calendar. A drug can go from speculative to approved — or collapse — in a single trading session. Here's exactly how the FDA review process works and how to use probability-of-approval scores to size your risk.
In This Guide
PDUFA stands for the Prescription Drug User Fee Act, a law first passed in 1992 that created a fee structure where drug companies pay the FDA to fund drug reviews. In exchange, the FDA commits to reviewing applications within defined timeframes. The target completion date for that review is called the PDUFA date.
In practical terms: a PDUFA date is the FDA's self-imposed deadline to either approve or reject a drug. It's the finish line for years of clinical development and regulatory filing — and for investors, it's often the single biggest binary event a biotech stock will ever face.
Companies with approaching PDUFA dates routinely see their stock move 40–200%+ in a single day, in either direction. That volatility is why tracking these dates is non-negotiable for biotech investors.
The path from a clinical drug to an FDA-approved product runs through two primary application types:
| Application Type | What It Is | Examples |
|---|---|---|
| NDA | New Drug Application — for small-molecule drugs (pills, capsules) | Most oral medications |
| BLA | Biologics License Application — for biologics (antibodies, cell therapies, gene therapies) | Monoclonal antibodies, CAR-T therapies |
Once a company submits an NDA or BLA, the FDA has 60 days to decide whether to formally accept it for review (the "filing decision"). If accepted, the review clock starts — and the PDUFA date is set.
The FDA assigns one of two review tracks, each with a different PDUFA timeline:
For drugs that offer standard therapeutic benefit. Represents the majority of NDA/BLA filings.
Granted for drugs that offer a significant improvement over available therapy. Faster timeline, higher investor attention.
In addition to review track, the FDA grants special designations that reflect development priority. You'll see these on the dansfera.com catalyst calendar:
Three outcomes are possible when the FDA reaches its PDUFA date:
The FDA grants approval and the drug can be marketed. This is the bull case — stocks often gap up significantly, especially for small-cap biotechs.
The FDA declines to approve and requests additional data, clinical trials, or manufacturing changes. Stocks typically drop 40–80%. A CRL is not a permanent rejection — companies can address the issues and resubmit.
The FDA issues a 3-month or 6-month extension, typically to review additional data submitted late in the review cycle. The PDUFA date gets pushed. Mixed market reaction — uncertainty often sells off.
The FDA usually announces its decision in the final 1–2 days before the PDUFA date. Companies receive the decision before it's public, but are required to disclose it via SEC filing within 4 business days.
Every PDUFA and AdCom entry on this calendar includes a Probability of Approval (PoA) score. These are Bayesian base rates derived from historical FDA approval data — not opinions or predictions.
| Application Type | Historical Approval Rate | Why |
|---|---|---|
| NDA (Standard Review) | 85% | Most drugs that reach NDA filing have robust Phase 3 data |
| NDA (Priority Review) | 90% | Priority review drugs often have unmet need advantage |
| BLA (Standard Review) | 80% | Biologics face more manufacturing complexity — slightly more CRL risk |
| BLA (Priority Review) | 88% | Priority biologics typically have strong efficacy data |
| Orphan / Rare Disease | 93% | FDA holds rare disease applications to a lower efficacy bar given unmet need |
| Supplemental NDA/BLA (new indication) | 92% | Already-approved drug; safety profile established; lower bar for new indication |
| Phase 3 Trial Readout (no NDA yet) | 58% | Phase 3 trials fail roughly 40% of the time — much higher binary risk |
How to use PoA scores: A high PoA (85–93%) doesn't mean no risk — it means the base rate of approval is high if you ignore drug-specific factors. The actual risk for a specific drug depends on clinical data quality, manufacturing readiness, and advisory committee signals. PoA scores are a starting point for due diligence, not a trading signal.
A drug with a prior Complete Response Letter (CRL) has a significantly lower PoA on resubmission — typically a 28-point penalty from the base rate — because the FDA already raised concerns.
The dansfera.com catalyst calendar aggregates every major FDA catalyst in one place — updated continuously with new PDUFA dates as companies announce FDA filing acceptances.
Here's what each entry on the calendar shows:
Filter tabs let you cut the view to just PDUFA dates, just AdCom meetings, just trial readouts, or just conferences. The "Upcoming This Week" section at the top surfaces the 4 most imminent catalysts with countdown timers.
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View the Catalyst Calendar →A few principles that hold across most PDUFA catalyst plays:
About 1–3 months before many PDUFA dates, the FDA convenes an Advisory Committee (AdCom) meeting — a panel of outside experts who vote on whether the drug should be approved. While the FDA doesn't have to follow the committee's recommendation, it does so the vast majority of the time. A positive AdCom vote is typically a major catalyst. A negative vote is a serious red flag. Watch AdCom dates closely — they often move stocks before the actual PDUFA date.
For high-PoA, well-known PDUFA dates, much of the approval probability is often already priced in by the time the decision arrives. Many traders reduce or exit positions before the binary event rather than hold through it. Understand the risk/reward before the date — not on the date.
A PDUFA decision for a large-cap like Eli Lilly or Pfizer typically moves the stock a few percent — it's one of many products. For a small-cap single-asset biotech, the same decision can be existential — the stock moves 40–300% in one direction. Position sizing should reflect this asymmetry.
Check whether a drug has received a prior CRL. The resubmission PoA is significantly lower — the FDA already raised concerns that took additional time and data to address. Manufacturing issues (CMC — Chemistry, Manufacturing, and Controls) are the most common CRL reason and can drag out timelines by years.