Conference run-up study

How biotech stocks that presented at a major medical conference actually traded into it — measured from D-30 and D-5 to the last close before the event. Built from 256 presentations across ASCO, ASH, ESMO, AACR and others, 2022-06-29 to 2026-01-09. Our own price data. Facts, not advice.

The headline finding is dispersion, not an edge.

Across all 256 presentations the median D-30 → D-1 move was −0.23% — essentially flat — but the middle half of events ran from −6.14% to +13.81%. The spread is the story. Anyone quoting you a single conference "run-up number" without a sample size and a quartile range is selling you something.

By market-cap tier

Cap tier	n	Median D-30 → D-1	25th pct	75th pct
Micro	62	+3.43%	−3.1%	+19.88%
Small	66	+7.9%	−12.9%	+26.85%
Mid	65	−0.96%	−4.22%	+10.7%
Large	63	−1.08%	−6.16%	+2.94%

Small- and micro-caps show the largest positive median and by far the widest spread. Large-caps drift slightly negative — a conference presentation is immaterial to a mega-cap's price. This is historical dispersion by cohort, not a prediction for any company.

By conference

Conference	n	Median D-30 → D-1	25th pct	75th pct
ASCO	81	−1.14%	−6.07%	+13.2%
ESMO	55	−3.01%	−8.05%	+6.04%
ASH	47	+8.74%	−2.47%	+19.76%
EHA	15	−0.85%	−4.53%	+10.4%
AACR	13	+8.01%	−0.37%	+34.17%
SITC	13	+4.02%	−1.56%	+29.32%
AASLD	8	−0.42%	−10.5%	+6.57%
EASL	7	−3.08%	−10.43%	+4.67%
WCLC	6	+2.72%	−2.57%	+6.93%

Only conferences with n ≥ 6 are shown. Small samples move a long way on one or two names — treat anything under n = 20 as indicative at best.

The shorter window (D-5 → D-1)

Window	n	Median	25th pct	75th pct
D-30 → D-1	256	−0.23%	−6.14%	+13.81%
D-5 → D-1	256	+0.59%	−2.72%	+4.93%

Method — and its limits

Anchor. We measure to the last daily close before the conference start date. Windows. D-30 (21 trading days) and D-5 (4 trading days). Universe. 256 presentations by listed US-traded biotechs at major medical conferences, 2022-06-29–2026-01-09, identified from company catalyst disclosures. Statistics. We report the median and the interquartile range, never a mean (a single 300% move would distort it) and never a "win rate."

Three caveats we think you should read.

1. Self-selection. Companies choose to present, and conferences accept abstracts they find interesting. Presenters are not a random sample of biotech — they are a sample that had something to show. Any apparent "presenter effect" is contaminated by that, and we make no causal claim.

2. Single anchor. For many conferences the abstract or late-breaker title drops weeks before the meeting — and that drop is itself a price event. Our windows are anchored on the conference start date only, so a move that happened on abstract release is partly captured and partly missed. We consider a dual-anchor version (abstract-drop and conference start) the correct way to do this, and we would rather tell you it is missing than quietly publish a number that pretends otherwise.

3. Small n. Several conferences here rest on fewer than 20 events. We publish the n next to every figure precisely so you can discount them yourself.

Not affiliated with or endorsed by the FDA or any medical society. pdufa.bio is an independent service. Informational and educational only — not investment advice. These are historical statistics; they are not a forecast for any company or event, they are not a trading strategy, and they carry no entry, exit or position-sizing guidance. Past price behaviour does not predict future outcomes. © 2026 pdufa.bio