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How Cerebras and SpaceX Structure IPO Lockups

IPO lockups are often talked about as if they are simple: insiders, employees, and early investors wait 180 days before they can sell. That six-month period remains the headline term in many of the current offerings, but there are exceptions where the actual release mechanics are often more nuanced. Cerebras and SpaceX are good examples.

Cerebras does not have one clean unlock date. Its lockup is staged, with different treatment for employees, directors, officers, and pre-IPO investors. Non-executive employees became eligible to sell 7.5% of eligible shares on the company’s first trading day and, once the stock closed more than 33% above its IPO price (also on the first trading day), another 7.5% on the second day of trading. Directors, officers, and pre-IPO investors did not get that same immediate liquidity. They will be eligible to sell 15% of their shares after the company reports first-quarter 2026 earnings.

More Cerebras shares unlock after second-quarter earnings and on several fixed dates in August, September, and October. Even then, a final portion stays locked until the earlier of the post-third-quarter earnings release date or the 180-day outside date.

SpaceX takes a different approach, but a similar structure applies. Elon Musk and certain significant investors have a much longer 366-day lockup, while some pre-IPO employees and general investors may receive earlier liquidity: up to 20% of eligible shares after SpaceX reports its first quarterly results as a public company, plus an additional 10% if the stock is at least 30% above the IPO price during five of 10 consecutive trading days before the earnings release date. Additional staggered releases follow, including after second-quarter earnings, but Musk and other top insiders are excluded from those early-release provisions.

Why IPO Lockup Terms Matter

These details matter to investors, as well as to employees. A staged lockup can reduce the risk of the large wave of selling that has historically weighed down the price of recently IPO’d stocks ahead of the more traditional 180-day trigger, and it may give employees or early investors partial liquidity sooner. At the same time, staggered releases can create multiple dates when new supply enters the market.

Additionally, lockups cover more than just selling shares. In both Cerebras and SpaceX, holders generally cannot use derivatives or other arrangements to hedge the economic risk of ownership while their shares are locked. Cerebras bars sales, pledges, option transactions, transfers, and swaps or similar arrangements that transfer the economics of the stock. SpaceX addresses the same issue through restrictions on short sales, hedging, and similar transactions. The wording is different, but the result is largely the same: holders generally cannot synthetically work around the lockup. Even after shares are released, trading windows, insider-trading rules, Rule 144, Rule 701, Section 16, and tax considerations may still apply.

Planning for Employees and Early Investors

For employees, executives, and investors with concentrated equity exposure, this is where thoughtful planning becomes important. The question is not just “when can I sell?” It is what can be sold, what remains restricted, what tax cost follows, whether hedging is allowed, and how liquidity fits into a broader diversification plan.

The broader lesson is simple: newly public stock can look straightforward from the outside, but the real planning work is often buried in the lockup language.

This article is based on publicly available filings and market data. It is for educational purposes only and should not be interpreted as legal, tax, or investment advice. Actual liquidity for any holder may depend on securities laws, company trading policies, individual agreements, tax considerations, and other restrictions.

Sources: Cerebras Systems Inc., Form S-1/A, Exhibit 1.1, Underwriting Agreement, Exhibit A, Form of Lock-Up Agreement, filed with the SEC on May 4, 2026; Cerebras Systems Inc., Form 424B4 final prospectus, filed with the SEC on May 14, 2026; Cerebras Systems Inc. investor-relations press release, “Cerebras Systems Announces Pricing of Initial Public Offering,” May 13, 2026; FactSet market data for CBRS first-day closing price; Space Exploration Technologies Corp., Registration Statement on Form S-1, filed May 20, 2026, SEC Accession No. 0001628280-26-036936, “Shares Eligible for Future Sale,” pp. 266–267; see also Exhibit 4.2, §1.14 and Exhibit 10.5, §§11(a), 12(a); SEC Investor.gov, “Updated Investor Bulletin: Investing in an IPO.”