What Is an IPO Lock-Up Period? Definition, How It Works and Examples

Before a company goes public, it and its lead underwriter put a lock-up agreement in place. The goal is to keep insiders’ shares from reaching the market too soon after the offering. The SEC describes the people covered broadly: company insiders, including employees, their friends and family, and venture capital investors. In practice, the signers are the directors, the executive officers and the larger shareholders. The IPO lock-up period meaning is the same for all of them. They cannot sell, pledge, short or hedge the shares. A short sale is a bet that the price will fall.

Holders who never signed are often bound anyway. Equity plans and investor agreements commonly include a market standoff clause. In it, the holder agrees in advance to the same restriction the underwriters later ask for. That is how a lock-up period stock option or RSU holder ends up locked, even a former employee who left years before the listing. The restriction came with the grant. In Airbnb’s December 2020 prospectus, lock-up agreements covered about 79.5% of the outstanding stock. Market standoff agreements covered substantially all of the rest.

Investors who buy shares in the IPO itself are not bound. Their shares are registered and trade from the first day. Underwriters still discourage “flipping,” or reselling right away. They do it by withholding future allocations from investors who flip.

What Is a Pre-IPO Lock-In Period?

The two terms mean different things in different markets. In the US, there is no lock-up as such before the listing. Transfer limits and rights of first refusal in the company’s documents do the same job. A right of first refusal lets the company buy the shares before an outsider can. In India, the regulator sets the “lock-in” itself. Under the ICDR Regulations of SEBI, India’s securities regulator, the promoters’ minimum contribution is locked in for 18 months. Promoters are the founders or controlling holders, and their minimum is 20% of post-issue capital. The lock-in becomes three years if most of the proceeds fund capital expenditure. Other pre-issue capital is locked in for six months, and shares from employee stock option schemes are exempt. In that market, an IPO lock-in period agreement is a compliance step set by the rules. Nobody negotiates it with the banks.

The typical lock-up period after an IPO is 180 days. The SEC puts the usual range at 90 to 180 days. Because the lock-up is a contract, the number in your company’s prospectus is the only one that applies. The SEC requires the terms to be disclosed there, under “Underwriting” and “Shares Eligible for Future Sale.” Check where the count starts. Airbnb’s agreement, for example, counts its days from the date of the prospectus.

Not every lock-up is a flat 180 days. Airbnb’s December 2020 prospectus combines four different devices in one agreement. Each of them can move the date a holder is free to sell.

An early release happens only when the agreement provides for it or the lead bank grants a waiver. Holders cannot demand one. Insiders who plan to sell the moment the restriction lifts often adopt a Rule 10b5-1 plan during the lock-up. That is a trading plan set in advance, and its cooling-off period has to run before the first trade.

An employee holds 40,000 vested shares when her company lists at $30. Her lock-up has an early-release clause like the one above. She may sell 25% after the first earnings release if the share has traded at least 33% above the offer price. Everything else is free at day 180.

The example shows the real risk of the holding period for IPO shares. The price can rise and fall while you are unable to act. Restricted shares can carry a second limit on top: a Rule 144 holding period. It runs six months from when you acquired the shares once the company has reported for 90 days, and one year before that. Check both dates.

The SEC is direct about it: a company’s stock price may drop in anticipation that locked-up shares will be sold when the lock-up ends. Field and Hanka’s 2001 paper, “The Expiration of IPO Share Lockups,” studied 1,948 agreements. They found little insider selling while lock-ups were in force. Around expiry, they found a three-day abnormal return of −1.5%, meaning the shares did 1.5% worse than the market. Trading volume rose 40% and stayed higher for good. Both effects were much larger for venture-backed companies, whose funds sold more aggressively than executives did.

The size of what is about to be released is no secret. The prospectus lists the market overhang, the shares outstanding but not yet tradable, and when each batch becomes eligible for sale. So an IPO lock-in period expiry is a known date with a known number of shares behind it. The market tends to price it in before it arrives.

Common Mistakes

• Assuming 180 daysRead your prospectus. Earnings-linked and staggered terms can end earlier or later.
• Thinking leaving the company frees youA former employee is often bound by the market standoff clause in the original grant.
• Hedging during the lock-upHedges such as collars, short sales and swaps on the locked shares are normally prohibited too.
• Ignoring tax timingRSUs can settle, and be taxed, while the shares are still locked. Read up on RSU taxes before the listing.
• Planning a sale for the first unlocked dayA 10b5-1 plan needs its cooling-off period to run first. Adopt it early if your company allows.

For the tax side of shares that settle at the listing, see RSU taxes. For the listing itself, see what an IPO is.

Lock-up agreement

A contract in which a holder agrees with the underwriters not to sell or hedge their shares for a period after the IPO.

Market standoff

A clause in an equity plan or investor agreement that binds the holder in advance to whatever lock-up the underwriters later require.

Restricted period

The window during which the lock-up applies. It is fixed in days or ends on an earnings-linked date.

Early release

A release of some locked shares before the period ends, by a trigger in the agreement or by the lead bank’s waiver.

Market overhang

The shares outstanding but not yet tradable after an IPO. The prospectus states how many, and when they become eligible for sale.

Flipping

Reselling shares bought in an IPO almost right away.

Rule 10b5-1 plan

A pre-arranged trading plan that lets an insider sell on a schedule set in advance.

IPO

A private company’s first sale of shares to the public, registered with the SEC and followed by a listing.

Figures were last checked on October 2, 2026. Lock-up terms are set offering by offering. The terms quoted here come from a single filed prospectus and show one possible structure. Other offerings differ. How a vehicle holding pre-IPO shares handles the end of a lock-up is explained in how exits work. The full Airbnb terms are in its final prospectus.