Anthropic considers limiting shareholder sales and extending lockup period for IPO

Anthropic, the AI company behind the Claude model family, is weighing a set of unusual controls for its anticipated IPO: letting some existing shareholders sell on day one while simultaneously extending the lockup period well beyond industry norms. The goal is straightforward. Keep the stock from whipsawing in its first weeks of trading.

The company confidentially filed its S-1 with the SEC on June 1, 2026, and a public version of that filing is expected by late August. The IPO itself is projected for October 2026, with estimates suggesting it could raise upwards of $60B and value Anthropic somewhere between $1 trillion and $2 trillion.

A trillion-dollar balancing act

For context, Anthropic completed a $65B Series H funding round in May 2026, which pushed its private valuation to roughly $965B. Q2 2026 revenues reportedly exceeded $11.5B, implying an annualized run rate of around $65B.

Standard IPO lockup periods typically run 90 to 180 days. Anthropic is reportedly considering pushing beyond that standard range, though the exact duration will be spelled out in the S-1 filing.

At the same time, the company is exploring a controlled release valve: allowing some existing shareholders to sell a limited number of shares on the first day of trading. A sudden lockup expiration, where millions of shares become eligible for sale on a single date, has historically created ugly price drops for newly public companies. Uber’s stock fell sharply after its lockup expired in 2019.

Mandatory trading plans and founder control

Beyond the lockup mechanics, Anthropic is reportedly planning to require employees to use 10b5-1 trading plans. These are pre-scheduled selling arrangements that insiders file in advance, specifying dates and quantities for stock sales.

On the governance side, public shareholders should not expect a seat at the table. Anthropic’s planned structure will preserve founder control through super-voting shares and a dedicated trust. No board-control concessions will be offered to public investors.

What this means for the IPO market

If Anthropic pulls off an IPO at the scale being discussed, a $60B raise would dwarf most recent tech IPOs. Extended lockups and mandatory trading plans aren’t new, but packaging them together with controlled day-one shareholder sales represents a more deliberate approach to supply management than most companies attempt.

The public S-1 filing, expected in late August, should clarify the specific lockup terms, the percentage of shares eligible for day-one sales, and the precise governance mechanics.

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