Updated July 29, 2026. Quick answer: Neither, strictly. No provision of the Securities Act, the Exchange Act, or 17 CFR imposes an IPO lock-up, defines one, or sets it at 180 days — a full-text search of all three returns zero hits for the word. But it is not always the underwriters either: a company can and does impose a lock-up on itself. The SEC rule that genuinely restricts when you can sell is a different one, Rule 144, and it runs on its own clock.
The answer, and why it is checkable rather than asserted
There is no lock-up statute and no lock-up rule, and the search for one is auditable. A full-text search of 17 CFR returns zero hits for “lock-up”, “lockup” and “lock up” — while control searches in the same scope return 557 hits for “underwriter” and 94 for “stabilizing”, so the zeros are real and not a failed query. The Securities Act of 1933 and the Securities Exchange Act of 1934 were each pulled in full and searched: zero hits in both, with controls confirming the text loaded. The 180 days is an underwriting convention, not a legal period.
The only federal duty attaching to a lock-up is a disclosure duty, and it does not come from the Plan of Distribution item everyone assumes. Regulation S-K Item 508 governs underwriter compensation, stabilization and penalty bids; it never mentions lock-ups. The hook is Rule 408, a catch-all: “there shall be added such further material information, if any, as may be necessary to make the required statements, in the light of the circumstances under which they are made, not misleading.” That says: if you have one and omitting it would mislead, disclose it. It creates no lock-up and sets no length.
Watch the government’s own wording. The SEC’s investor-education entry says lock-ups “may vary, but most prevent insiders from selling their shares for 180 days” and that “U.S. securities laws require a company using a lockup to disclose the terms.” Both qualifiers are load-bearing: most is an observation about market practice, and using makes the duty conditional on a choice the company already made. Read quickly, the sentence is the origin of the widespread belief that 180 days is legally mandated.
“No underwriters” does not mean no lock-up
Palantir listed directly on the NYSE in September 2020. Its own registration statement says “There are no underwriters.” The same document says its executive officers, directors and record holders of over 99% of capital stock “are subject to market standoff or lock-up agreements with us” — the counterparty is the company. Two further details worth carrying: the release was an event, not a duration (“the start of the third trading day following the date of public disclosure of our financial results for the year ending December 31, 2020”), and holders who had not signed the lock-up were “therefore not permitted to sell any shares” — signing the restriction was how you got liquidity.
| Belief | What the sources actually show |
|---|---|
| The SEC requires a lock-up | Zero hits in the 1933 Act, the 1934 Act and 17 CFR |
| The period is 180 days | Market convention. Palantir’s ran to an earnings event |
| Underwriters always demand it | Palantir had none and imposed one on itself |
| It is in the Plan of Distribution | Item 508 does not mention lock-ups; Rule 408 is the hook |
| A lock-up delays your tax | Treas. Reg. §1.83-3(c)(4), Example 6 says the opposite |
What follows for you
Your release date is a term of your own document, not a rule anyone can look up on your behalf. The constraint that is law is Rule 144, whose clock runs from acquisition and is gated on the issuer’s reporting history — and for employee shares Rule 701 usually relieves part of it ninety days after the company becomes a reporting company.
Sources
Securities Act of 1933 (15 U.S.C. ch. 2A) and Securities Exchange Act of 1934 (15 U.S.C. ch. 2B), both pulled in full and searched; 17 CFR Title 17 searched in full text; 17 CFR 229.508 (Regulation S-K Item 508); 17 CFR 230.408; 26 CFR 1.83-3(c)(4) Example 6; Palantir Technologies Inc. Form S-1/A, September 21, 2020; SEC Investor.gov, Initial Public Offerings: Lockup Agreements. All read July 2026.
This states what the cited authority says. It is not tax, legal or investment advice. Lock-up terms, award agreements and plan documents vary, and both the securities and the tax analysis turn on facts about your role and holdings that no page can see.