As explained here, the IPO lock up period is

...a period of time after a company has initially gone public, usually between 90 to 180 days. During these initial days of trading, company insiders or those holding majority stakes in the company are forbidden to sell any of their shares. Once the lock-up period ends, most trading restrictions are removed.

On another hand, the "quiet period" is, according to the definition provided here

In terms of an IPO, the period where an issuer is subject to a SEC ban on promotional publicity. The quiet period usually lasts either 40 or 90 days from the IPO.

Looking at these definitions, it seems that it is likely that the share prices fall at the end of the lock up period (being that company "insiders", such as employees who had received shares as part of their contract, can then freely sell their shares).

On another hand, according to this article things may seem different near the end of the quiet period. The article states that

The IPO quiet period is a period of time post a company's IPO, in which its underwriters are unable to release reports or recommendations on the stock. Following the expiration, these reports are often positive, widely distributed, and lead to a temporary boost in stock price.

I do not have access to the report that the author is referring to in his article (after some digging it may be this one but requires a subscription).

So the questions I wanted to ask are:

  1. Is there evidence of increase in the value of an IPO stock at the end of the quiet period?
  2. Since both "lock up period" and "quiet period" can have a duration of 90 days, is it possible that they end on the same day?

1 Answer 1


I'll answer your second question. No, the quiet period and lock up period cannot end on the same day. Quiet periods will end (usually) around the time the company goes public. Lock up periods usually start around the time the company goes public, and end several weeks after the IPO.

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