IPO Lock-Ups: The 180-Day Date Matters Less Than Who Signed

On October 22, up to 1.3 billion SpaceX shares came free to sell, 28% of those under its 180-day lock-up. That wasn't the end of the lock-up. It was the seventh of 15 release dates in the prospectus, and the last 180-day tranche, up to 797.6 million shares, comes on December 8. About 60% of the company, including every share Elon Musk owns, sits under a longer lock-up that releases into mid-2027.

That is a long way from the textbook, where insiders wait 180 days and everything comes loose on day 181. We read the lock-up terms in the prospectuses of 440 US IPOs from January 2024 to October 2026 to see how much of the textbook still holds.

Six months still holds

392 of the 440 (89.1%) lock up insiders for 180 days or six months. 21 use one year and 19 use 90 days.

The biggest deals release early

26 IPOs let some locked shares sell before the period ends, in three ways that deals often combine: after a named earnings report, once the stock closes well above the IPO price, or on a fixed schedule. Reddit's lock-up ended on the third trading day after its June 2024 quarter results. CoreWeave, Figma, StubHub and Netskope combined the earnings and price triggers.

Size is the dividing line. Among the 43 IPOs with the most trading in their first 20 sessions, 14 had an early release. Among the 320 with the least, 3 did. None of the 180 Nasdaq Capital Market IPOs had one.

In small IPOs, fewer people sign

A lock-up binds only the people who sign it. On Nasdaq's larger tiers and the NYSE, 134 of 210 prospectuses bind all or substantially all shareholders. On the Nasdaq Capital Market, 154 of 180 (85.6%) bind only the directors, officers and largest holders, usually those with 5% or more.

The day itself is quiet

A 2001 study of 1,948 lock-ups by Laura Field and Gordon Hanka found a 1.5% drop against the market over the three days around the end. We ran the same test on the 330 standard lock-ups in our sample that have ended. The median stock beat the SPY S&P 500 fund by 0.7%, and 154 of the 330 fell. The same stocks a month earlier had a median of -1.2%, so the expiry didn't stand out.

Volume is different. In the 80 deals on the larger exchanges where substantially all holders were locked up, volume on the first three days ran a median 1.34 times the prior month's average, against 0.90 a month earlier. The date is printed months ahead, so a trader can act before it. The new supply can only change hands once it is free.

Few insiders rush to sell

Only 32 of 322 companies had a Form 144 notice of a planned sale in the month after the lock-up ended. The filings came at a steady pace for two months, not in a burst on day one.

Dates coming up

Cerebras and Blackstone Digital Infrastructure Trust reach day 180 on November 9, and Fervo Energy on Sunday, November 8. INNIO and Quantinuum follow on November 30, and SpaceX on December 8.

The useful question about a lock-up isn't when it ends. It's who signed it and what can end it early, and the prospectus answers both. The full study has the charts, the calendar for 12 companies and the method.

Data: SEC prospectuses, Form 144 filings and daily prices, processed by Equibles.