What is an IPO lock-up?
Before a company lists, its founders, staff and early backers already own shares. A lock-up is their promise not to sell those shares for a set time after the IPO.
The promise is made to the underwriters, the banks that manage the offering and sell the new shares to the public. In Oura's S-1/A, the company, its officers, its directors and holders of substantially all its shares sign one. They agree not to sell or hedge for 180 days after the prospectus date.[S2]
"Lock-up expiry" is the day those limits end. In the five filings cited here, it is counted in days from the date of the prospectus.
Why is it easy to misread?
Many first-time readers assume the lock-up is a legal rule, or that every share is free the day it ends. Neither is quite right.
A lock-up is a private contract, and the banks can release shares early. Separate SEC rules, Rule 144 and Rule 701, keep limiting some sales after the contract ends.[S2]
There is a close cousin with a different name. A "market standoff agreement" is a similar promise made to the company rather than to the banks. Anthropic's S-1 says its directors, officers and substantially all its holders are bound by one or the other.[S1]
Which shares are locked up, and which are not?
Shares sold in the IPO are usually free to trade at once. Oura's S-1/A says this, with one exception: shares bought by its "affiliates".[S2]
An affiliate is a person or firm that controls the company, is controlled by it, or is under common control with it.[S6]
Shares issued before the IPO are "restricted securities". Oura's S-1/A says 270,945,459 of its 320,945,459 shares after the offering would be restricted.[S2]
Where does an S-1 describe the lock-up?
Look in four places. The summary's "The Offering" table has one row naming the period and the banks whose consent is needed.[S4]
The risk factors discuss future sales of shares. "Shares Eligible for Future Sale" has a table of when blocks of shares can first be sold. It also sums up Rules 144 and 701.[S1]
"Underwriting" carries the full terms and the exceptions, such as gifts and transfers to family trusts.[S3]
What do the S-1s of IPOs on Cityfort say?
Anthropic (S-1, Oct 26, 2026). Non-founder directors, officers and certain holders are locked up until the earlier of two dates. One is the second full trading day after its results for the quarter ending Mar 31, 2027; the other is day 180.[S1]
Its seven co-founders and certain other holders have a longer period. It ends at the earlier of the second full trading day after results for the quarter ending Sep 30, 2027, or day 365.[S1] Shares are released in stages along the way; the share counts are blank in this filing.[S1]
Oura (S-1/A, Sep 21, 2026). The main period is 180 days, and early release needs Goldman Sachs' written consent. Shares are set to be released in stages from day 35 to day 181.[S2]
Oura also has three price-based stages, each for about 17.0 million shares. Each needs the closing price to be at least 25%, 33% or 40% above the IPO price. The price test counts any 5 of 10 consecutive trading days.[S2]
Those conditions must be met within the first 60 calendar days. Oura says it would announce each such release on a Form 8-K.[S2]
Nscale (S-1, Sep 18, 2026). The period is 180 days; early release needs consent from at least two of Goldman Sachs, J.P. Morgan and Morgan Stanley.[S3]
If the lock-up would end inside a "Blackout Period", as the agreement defines it, it ends some trading days earlier. The number of days is blank in the S-1.[S3]
Holders may set up a Rule 10b5-1 trading plan during the lock-up. No locked-up shares may be sold under that plan until the lock-up ends.[S3]
SB Energy (S-1/A, Sep 21, 2026). The period is 180 days, and release needs the permission of J.P. Morgan, Goldman Sachs and Morgan Stanley.[S4]
Shares handed to the limited partners of Energy Global at closing are covered too. Releasing certain holders early triggers a pro rata release for SoftBank, OpenAI and NVIDIA.[S4]
Wella (S-1/A, Sep 23, 2026). The period is 180 days. The banks "may, in their sole discretion and at any time without notice," release shares early.[S5]
Wella expects some existing holders to count as affiliates when the lock-up ends, because of their stakes or board seats.[S5]
How is an early release announced?
FINRA, the self-regulatory organization that oversees US broker-dealers, sets one rule for officers and directors. Their lock-ups must provide that the lead bank notifies the company of a release or waiver at least two business days ahead.[S8]
The lead bank must also announce it through a major news service. Releases only to allow a transfer for no value, or to immediate family, are exempt if the person receiving the shares agrees in writing to the same lock-up.[S8]
Some S-1s add their own notices. Oura's names a Form 8-K; Nscale's names a major news service or a Form 8-K.[S2][S3]
What limits sales after the lock-up ends?
Rule 144 sets the conditions for selling restricted shares in the market. An affiliate may sell, in any three months, no more than the greater of two amounts.[S6]
One is 1% of the shares of that class outstanding. The other is the average weekly trading volume over the four calendar weeks before the sale notice.[S6]
An affiliate must file a Form 144 notice when sales in three months exceed 5,000 shares or $50,000.[S6]
There is also a holding period. It is six months from when the shares were acquired, if the company has been subject to SEC reporting for at least 90 days. Otherwise it is one year.[S6]
Where does Rule 701 fit in?
Rule 701 covers shares that a private company gave staff and advisers under written pay plans, such as stock options.[S7]
Ninety days after the company becomes subject to SEC reporting, non-affiliates may resell those shares under Rule 144. They can skip its holding period and current-information conditions.[S7] Affiliates may skip only the holding period.[S7]
Anthropic's S-1 notes that holders of Rule 701 shares wait until 90 days after the prospectus date. The lock-up still applies on top, for as long as it runs.[S1]
How do the pieces fit together?
After listing, trades by directors and officers are reported to the SEC on Form 4. Our guide to Form 4 insider filings explains the deadline and how to read one. For how an S-1 is laid out, see how to read an S-1.