IPO Lockup Expiration Explained: 180-Day Lockups
How IPO lockup expirations work: the typical 180-day period, where lockup terms are disclosed, how early releases are announced, and how leak-outs cap selling.
What is a lockup expiration?
A lockup is a contractual promise by existing holders not to sell (or hedge) their shares for a set period after an offering. In a US IPO, officers, directors, employees and pre-IPO investors typically agree with the underwriters not to sell for 180 days after the offering, although shorter and longer periods are used.
When the period ends, those shares can generally be sold, subject to securities law limits such as Rule 144.
The lockup expiration does not create new shares. It changes how many existing shares are eligible to be sold, which can enlarge the tradable supply relative to the public float from the IPO. A leak-out agreement is a related tool that, instead of banning sales outright, caps how much a holder can sell over a period.
How a lockup works
Lockups are private agreements, usually between each locked-up holder and the lead underwriters. No SEC rule requires one, but almost every underwritten IPO has them, because underwriters want an orderly market for the newly issued shares. A typical lockup:
- Covers common stock and securities convertible into it, such as options and warrants, plus short sales, swaps and other hedges that would transfer the economic risk.
- Runs from the date of the final prospectus for a fixed period, commonly 180 days for an IPO, and often 60 to 90 days for a follow-on offering.
- Permits listed exceptions, such as gifts, transfers to family trusts, and sales under pre-existing trading plans.
- Can be waived by the underwriters, in whole or in part.
A worked example
Hypothetical Company X completes an IPO, selling 10,000,000 new shares. It already had 40,000,000 shares held by founders, employees and venture investors, all locked up for 180 days.
| During the lockup | After expiry | |
|---|---|---|
| Shares outstanding | 50,000,000 | 50,000,000 |
| Shares freely tradable | 10,000,000 | up to 50,000,000 |
| Freely tradable as % of outstanding | 20% | up to 100% |
Hypothetical figures, before any affiliate restrictions under Rule 144.
Where lockup terms are disclosed
The final prospectus, filed as a 424B4 for most IPOs, is the primary source:
- "Underwriting" describes the lockup agreements, their length, who signed and the exceptions.
- "Shares Eligible for Future Sale" sets out how many shares become sellable and when, including the effect of Rule 144.
- The underwriting agreement, filed as an exhibit to the registration statement, contains the full lockup terms.
Counting 180 days from the prospectus date gives the scheduled expiry, but some lockups end on a different trigger, such as a set number of trading days after an earnings release.
Early releases and waivers
Lockups often contain built-in early release provisions. Common forms include:
- Price-based release. A portion of locked shares is released if the stock closes above a set premium to the IPO price (for example 25% or 33%) for a set number of trading days.
- Earnings-based release. A portion is released shortly after the company reports results, often so that holders are not stuck in a closed trading window when the lockup ends.
- Staged release. Fixed percentages unlock at different dates.
Underwriters can also grant discretionary waivers. Under FINRA Rule 5131(d)(2), lockup agreements for officers and directors must provide that, at least two business days before a release or waiver, the lead manager notifies the company and the release is announced through a major news service. A natural expiration already disclosed in the prospectus does not require a new announcement.
After expiry: Rule 144 and insider reporting
Expiry removes the contractual barrier. Securities law limits still apply:
- Restricted securities acquired before the IPO generally must meet Rule 144's holding period (six months for a company that has been reporting for at least 90 days, one year otherwise) before public resale without registration.
- Affiliates, such as officers, directors and large holders, are subject to Rule 144's volume limit: in any three months, no more than the greater of 1% of shares outstanding or the average weekly trading volume over the prior four calendar weeks. Affiliates selling more than 5,000 shares or $50,000 in three months file a Form 144.
- Officers, directors and 10% holders report sales on Form 4 within two business days.
For Company X, 1% of outstanding is 500,000 shares. If average weekly volume is 2,000,000 shares, an affiliate can sell up to 2,000,000 shares in a three-month period under the volume limit.
Leak-out agreements
A leak-out agreement limits selling rather than prohibiting it. Typical terms cap a holder's daily sales at a percentage of the stock's daily trading volume, or a fixed number of shares per day or week, for a set period. They are common in PIPE transactions, convertible financings and resale registrations, where a selling shareholder receives shares that could otherwise be sold all at once.
For example, a leak-out capped at 10% of daily volume, on a day when 3,000,000 shares trade, permits sales of up to 300,000 shares that day.
How to track lockups on Signal8
- The market calendar shows scheduled corporate events, including lockup-related dates where available.
- The live SEC filings feed shows the 424B4 prospectuses where lockup terms are disclosed, and the Form 4 and Form 144 filings that follow.
- The insiders pages collect Form 4 transactions by insider and company.
For how new and newly sellable shares affect ownership, see What Is Dilution?. Shares sold by selling shareholders after a private placement are often registered on a resale S-1, and affiliates file a Form 144 before selling.
FAQ
How long is a typical IPO lockup period?
The most common IPO lockup is 180 days from the date of the final prospectus. Shorter periods, such as 90 days, and longer or staged lockups also appear, and follow-on offerings commonly use 60 to 90 days. The exact length, the holders covered and the exceptions are disclosed in the "Underwriting" section of the prospectus and in the underwriting agreement.
Does a lockup expiration create new shares?
No. A lockup expiration does not change the number of shares outstanding. It allows existing shares that were contractually restricted to be sold, so the number of shares that could trade increases. Securities law limits such as Rule 144's holding period and affiliate volume limits can still restrict sales after the lockup ends.
Can a lockup end early?
Yes. Many lockups include early release provisions tied to the stock price, an earnings release or a set schedule, and underwriters can waive a lockup for some or all holders. FINRA Rule 5131 requires a release or waiver for officers and directors to be announced through a major news service at least two business days before it takes effect.
What is a leak-out agreement?
A leak-out agreement limits how much stock a holder can sell over a period rather than prohibiting sales. Typical terms cap daily sales at a percentage of trading volume or at a fixed number of shares. Leak-outs are common in private placements and convertible financings, where investors receive shares that could otherwise be sold in a short time.
See it on DilutionScan
Companies DilutionScan covers, with the instruments read from their SEC filings. Open one to see each instrument and the filing it came from.
- GNSGenius Group Limited8 warrant series, 1 convertible, 1 ATM program, 3 shelf registrations and 2 completed offerings on file
- SMXSMX (Security Matters) Public Limited Company Ordinary Shares10 warrant series, 8 convertibles, 2 equity lines, 4 shelf registrations, 4 S-1 registrations and 2 completed offerings on file
- MLGOMicroAlgo, Inc. Ordinary Shares2 warrant series, 5 convertibles and 2 shelf registrations on file
- HOLOMicroCloud Hologram Inc. Ordinary Shares2 warrant series, 1 convertible, 3 shelf registrations and 2 completed offerings on file
Terms in this guide
- Lockup agreement
- A lockup agreement is a promise by insiders or investors not to sell or transfer their shares for a set period, commonly 90 to 180 days after an IPO or an offering.
- Leak-out agreement
- A leak-out agreement is a contractual limit on how many shares a holder may sell per day or per period, often a percentage of daily trading volume, so a large block is not sold at once.
- Rule 144
- Rule 144 is the SEC safe harbor that lets holders publicly resell restricted or control securities without registration once conditions such as a holding period are met.
- Form 4
- Form 4 is the SEC filing that officers, directors and holders of more than 10% must make within two business days to report a change in their holdings of the company's securities.
- Public float
- Public float is the shares held by investors other than a company's officers, directors and controlling holders, or their market value; the SEC uses the dollar figure for form eligibility.
- Selling shareholder
- A selling shareholder is a holder named in a resale registration statement whose shares are being registered so that holder, not the company, can sell them publicly.
- PIPE (private investment in public equity)
- A PIPE (private investment in public equity) is a private sale of unregistered shares, warrants or convertibles by a public company to selected investors, usually followed by a resale registration.
Related guides
- What Is Stock Dilution? How New Shares Affect YouStock dilution explained with worked numbers: what happens to your ownership when a company issues new shares, and where to spot it coming in SEC filings.
- Uplisting Explained: Moving From OTC to Nasdaq or NYSEWhat an uplisting from OTC to Nasdaq or NYSE involves, the listing standards a company must meet, and what FINRA's OTC daily list records when it moves.
- Form 144 Explained: Notice of Proposed SaleForm 144 explained: who files a notice of proposed sale, the 5,000-share and $50,000 thresholds, Rule 144 volume limits, and why it does not prove a sale.
- Form 4 Transaction Codes Explained: P, S, A, M, FForm 4 transaction codes explained: what P, S, A, M, F, G and X mean, why code F is not an insider sale, the two-day filing deadline and 10b5-1 footnotes.
- Short Interest Explained: Days to Cover and BorrowHow short interest is reported to FINRA twice a month, how to calculate days to cover and short % of float, and how borrow fees and the Reg SHO list work.
- Short Interest vs Short Float: Which Number Matters for a SqueezeShort interest is a FINRA share count; short float is that count divided by a float. Why the two differ, which dates they carry, and how to read each.
Check any ticker for dilution
DilutionScan reads each covered company's SEC filings and lists its warrants, convertibles, ATM programs, shelves and S-1s on one page, with a dilution rating and cash runway.
This guide is from the Signal8 Academy, the research team behind DilutionScan. Educational content only. DilutionScan and Signal8 are not broker-dealers or investment advisers, and nothing here is a recommendation to buy or sell any security.