ZYME - FDA decision on Aug 25: opportunity or already priced in?

I’ve been looking at Zymeworks ($ZYME) ahead of the Aug 25 FDA PDUFA date for Ziihera (zanidatamab) in first-line HER2+ gastroesophageal adenocarcinoma.

I’m relatively new to trading biotech catalysts, so I’m posting this mainly to have people poke holes in the thesis rather than to pitch the stock.

The bull case as I understand it:

\- Ziihera already has strong Phase 3 data behind it.
\- FDA decision is due Aug 25.
\- Approval would trigger a $250M milestone payment to Zymeworks.
\- That’s pretty material for a company that reported about $322.5M in cash, equivalents and marketable securities at the end of June.
\- Zymeworks also keeps royalties on Ziihera sales.
\- The company itself has been buying back stock: \~$49.4M repurchased in 2026 through Aug 4 at an average of $25.04/share.
\- Citi recently put ZYME on an upside catalyst watch, saying FDA approval looks meaningfully derisked, with a $37 PT.
\- Longer term there’s also the rest of the pipeline and the Theravance acquisition.

But here’s what makes me hesitant:

ZYME has already run from roughly $22 at the beginning of August to \~$26+.

So I’m wondering whether the obvious trade has already happened.

If everyone knows the Phase 3 data are good and expects FDA approval, then an approval on Aug 25 might only produce a modest move - or even a classic sell the news reaction.

Meanwhile, an unexpected CRL could presumably hit the stock much harder.

So the setup might effectively be something like:

High probability of approval / relatively limited upside

vs.

Low probability of rejection / very large downside

Which isn’t necessarily a good trade even if the probability of approval is 80-90%.

I’m interested in using this as a small options trade/experiment. I’m not necessarily bullish - I’d consider either a call or a put depending on the risk/reward and what the options market is already pricing in. At this point I’m wondering whether the obvious bullish entry was several weeks ago rather than right before PDUFA.

For people who actually follow biotech / ZYME:

1. How much of the approval do you think is already priced in?
2. What price reaction would you expect on approval?
3. What downside would you expect from a CRL?
4. Is there something important in the FDA/regulatory story I’m missing?
5. Anyone looking at the options chain - what does it tell you about the expected move?
6. Would you actually take this trade before Aug 25, or is the risk/reward now unattractive?

Not looking for 🚀 - tell me why this is a bad trade.