Biotech IPO Lockup Expirations: The 180-Day Selloff

Every biotech IPO plants a time bomb. Ninety to 180 days after the offering, the lockup expires and the shares held by venture funds, insiders, and pre-IPO investors suddenly become sellable. The date is public months in advance. Yet the selloff still catches retail holders by surprise every time, because most people never check the calendar.

The fix: find the lockup date in the prospectus, understand who’s likely to sell, and position before it happens. The selloff was never a mystery. It was on the calendar.

Step 1: Know what a lockup is

A lockup is a contractual agreement that prevents pre-IPO shareholders from selling their stock for a set period after the offering, usually 90 or 180 days. It exists to stop a flood of shares from hitting the market and crushing the price in the first weeks of trading. The people bound by it: founders, executives, employees, and the VCs and crossover funds that owned the company before the IPO. When the lockup expires, every one of them is free to sell at once.

Finding the exact date takes five minutes. Pull the company’s S-1 or prospectus on SEC EDGAR and search for “lock-up.” The date is stated plainly. Most lockups run 180 days from the pricing date, so you can also add 180 days to the IPO date and be close. Sites like MarketBeat’s lockup calendar publish the dates for you.

Step 2: Understand why biotech is uniquely vulnerable

Lockup selloffs are worse in biotech than almost anywhere else, for three reasons. First, the companies are pre-revenue: there’s no earnings floor to catch a falling stock. Second, the sellers’ cost basis is a fraction of the IPO price. A VC that bought at $2 a share in a Series A is thrilled to sell at $15, and a fund distributing returns to its own limited partners is a forced seller, not a panicked one. Third, ownership is concentrated and the float is small, so even a modest percentage of insiders selling moves the price hard. If you want to understand how share count and float pressure a stock, see the dilution survival guide.

Step 3: Learn the pattern

The typical shape: the stock drifts down in the weeks before the expiration as the market prices in the supply, then sees a volume spike on the expiration day itself, then carries an overhang for weeks after as more sellers trickle out. But the move is usually smaller than the fear. Research is consistent here: the average stock drops only 1-3% around lockup expiry, but the bottom quartile drops 10-15% relative to the prior month. The tail is where the damage lives, and pre-revenue biotech names are overrepresented in that tail. On the expiration day itself you’ll often see several times the normal volume, which is the moment the overhang starts clearing. The overhang isn’t over when the volume spike ends; it’s over when the forced sellers have finished distributing, which can take weeks.

Step 4: Screen for upcoming expirations

Build the list yourself. Track IPO dates (see how to evaluate a biotech IPO), add 180 days, and flag the names. The 2026 cohort is a good place to start: Parabilis Medicines priced June 10, Kailera Therapeutics April 16, Generate Biomedicines February 26, Braveheart Bio August 5. Each has a lockup date you can circle right now.

Generate Biomedicines (GENB) is the immediate one. It priced February 26, 2026 at a $2.04 billion valuation and raised $400 million. Its 180-day lockup expires in late August 2026, and the stock was already trading below its offer price ahead of that date. That’s the setup, not a coincidence.

Step 5: Decide how to play it

You have two options. Trade the overhang: if you expect heavy selling, get out (or short) before the expiration and look to re-enter after the supply clears. Or wait for clearance: hold cash and buy after the expiration, once the forced sellers are done and the price has absorbed the supply. Both are legitimate. The edge is in reading seller quality.

A venture fund at the end of its fund life has to distribute. A founder who just raised the company’s war chest and holds a 15% stake usually doesn’t. Check the S-1’s “Principal and Selling Stockholders” section to see who holds what, then ask whether each one is a forced seller. Position size matters here more than direction: if you’re wrong about a seller’s intentions, you want to be wrong small. Reading seller quality is the same skill as reading insider signals in general; see how to read insider buying and selling.

Step 6: Be honest about the edge

Lockup expiry is the single most widely known event on a biotech’s calendar, and the market mostly prices it in. You are not finding a free arbitrage. The edge, if you have one, is timing (getting out before the overhang, not after) and seller-quality analysis (knowing which expirations will actually see selling). Some expirations are complete non-events: the insiders hold, the volume never comes, the stock barely moves. If you treat every lockup as a guaranteed crash, you’ll trade yourself out of good positions for nothing.

Common mistakes

Holding through an expiration you never checked. The date was public months ago; you just didn’t look.

Assuming every lockup is a crash. Most are 1-3% events; only the forced-seller cases make the 10-15% tail.

Ignoring seller quality. A distributing VC fund and a holding founder produce completely different expirations.

Buying the day before expiration to catch the dip. You’re stepping in front of the exact supply you should be waiting out.

Final checklist

• Find the lockup date in the S-1 (or add 180 days to the IPO date).
• Who’s bound by it, and how much do they hold?
• Is each seller a forced seller (VC distribution) or a long-term holder (founder)?
• Is the company pre-revenue, and how small is the float?
• Have you decided: trade the overhang, or wait for clearance?