What Is a Lock-Up Period?
A lock-up period is a contractual restriction that bars founders, executives, employees, and pre-IPO investors from selling their shares for a set stretch of time after the company goes public. The standard term is 180 days from the IPO, though some deals run 90 days and others use staggered schedules that release shares in tranches. The restriction comes from agreements with the underwriters rather than from any securities law.
The logic is straightforward. A newly public company usually floats only 10 to 25% of its shares in the IPO, leaving insiders holding the vast majority. If those holders could sell immediately, the potential supply would overwhelm early demand and undermine the offering price the underwriters worked to establish. The lock-up gives the stock time to develop a natural trading base first.
How Lock-Ups Work in Practice
Lock-up agreements are signed with the lead underwriters as a condition of the offering, and the banks retain discretion to release holders early. Modern deals increasingly include early release triggers, for example allowing a portion of employee shares to be sold once the stock trades a set percentage above the IPO price for several days, or opening a window after the first earnings report.
Expiration is a well-telegraphed event, since the date is disclosed in the prospectus. Stocks often decline into and around lock-up expiry as the market anticipates insider selling, with studies showing an average drop of roughly 1 to 3% around the event and sharper moves when insiders hold an especially large share of the float. Some sponsors manage the transition by selling through organized secondary offerings instead of open-market sales.
Why Lock-Up Periods Matter
Traders track lock-up calendars to position around expected supply, while long-term investors treat expiry as a chance to buy quality companies at temporarily depressed prices. The dynamic was vivid in high-profile tech listings: Facebook's stock slid into its staggered 2012 lock-up expirations, while other companies have sailed through expiry when insiders signaled they intended to keep holding.
The concept extends beyond IPOs. Hedge funds and private equity funds impose lock-ups on their own investors, commonly one year for a new hedge fund commitment, to keep capital stable. In SPAC mergers, sponsors typically face lock-ups of up to one year on their founder shares. For interviews, know the standard 180-day IPO term and be ready to explain why expiration can pressure a stock.
