What Is a Lockup Period? IPO Selling Restrictions

A lockup period is a contractual restriction that prevents company insiders — founders, executives, employees, and early investors — from selling their shares for a specified period after an initial public offering. The standard lockup is 90-180 days, though some are longer. Lockups exist to prevent the market from being flooded with insider shares immediately after the IPO, which would overwhelm demand and crash the stock price before the company has a chance to establish itself in public markets.

Why Lockups Matter

At a typical IPO, only 10-20% of the company's total shares are sold to the public. The remaining 80-90% are held by insiders who are restricted from selling during the lockup period. When the lockup expires, this massive pool of shares becomes eligible for sale — potentially tripling or quadrupling the supply of tradeable shares overnight.

The supply-demand math is straightforward: if the number of shares available for sale increases dramatically while demand stays constant, the price falls. Research in the Journal of Financial Economics shows that stocks decline an average of 1-3% in the days surrounding lockup expiration, with higher declines for stocks with larger insider holdings relative to the public float.

How to Trade Around Lockup Expirations

Lockup expiration dates are disclosed in the IPO prospectus (S-1 filing) and can be found on financial data providers. Sophisticated investors mark these dates and either avoid buying before expiration (waiting for the potential price decline) or short the stock in anticipation of selling pressure.

Not all lockup expirations produce selling. If the stock has declined significantly below the IPO price, insiders may hold rather than sell at a loss. If the company's outlook is strong, insiders may hold for further appreciation. The magnitude of the lockup effect depends on insiders' desire and incentive to sell — which varies with stock performance, insider wealth concentration, and tax considerations.

Lockup Expirations and Quality Investing

For quality investors evaluating recently IPO'd companies, the lockup expiration is a potential buying opportunity. If a genuine quality business drops 5-10% on lockup-related selling pressure (which is mechanical, not fundamental), the decline creates a better entry point on the same business. The selling is temporary supply — once insiders who wanted to sell have sold, the overhang clears and the stock can trade on fundamentals.

However, heavy insider selling after lockup expiration can be a warning signal. If the CEO, CFO, and board members sell significant portions of their stakes at the first opportunity, it may indicate they believe the stock is overvalued or the outlook is weaker than public presentations suggest. Insiders who hold through lockup expiration are signaling conviction; those who sell immediately may be signaling the opposite.