How to Read an FDA AdCom Vote

What Is an FDA Advisory Committee?

An FDA Advisory Committee, commonly called an AdCom, is a panel of independent medical experts convened by the FDA to evaluate whether a drug should be approved. The panel reviews clinical trial data, hears presentations from the drug sponsor and FDA reviewers, and then votes on specific questions.

AdCom meetings are public events, broadcast live on the FDA's website. Stocks can swing 20–50% during a single AdCom session.

How to Interpret the Vote Count

A strong favorable vote (12-1 or 10-2) is a clear bullish signal. The FDA follows favorable recommendations roughly 80% of the time. A narrow vote (7-6 or 8-5) is more ambiguous. A negative vote is typically devastating — the FDA follows negative recommendations about 75% of the time, though there are notable exceptions.

What the Discussion Reveals Beyond the Vote

Experienced traders pay as much attention to the panel discussion as the vote. If multiple panelists vote yes but express cardiac safety concerns, the FDA might approve with a REMS requirement limiting patients. A yes vote with REMS concerns is very different from a clean yes. The FDA reviewer's presentation before the vote often signals the agency's preliminary thinking.

AdCom's Effect on the PDUFA Date Trade

If the AdCom vote is strongly positive, the PDUFA date becomes a lower-volatility event because approval is largely expected. If the vote is negative but the stock doesn't collapse, the PDUFA date becomes extremely high-stakes. If there is no AdCom at all, the PDUFA date carries maximum uncertainty and typically produces the largest moves.

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