Anthropic is reportedly structuring its highly anticipated initial public offering to permit current shareholders to sell a portion of their holdings, while simultaneously considering a lock-up period that extends beyond the standard timeframe, according to sources familiar with the matter.

The inclusion of a secondary share sale component would set Anthropic apart from this year's other major tech listings, including SpaceX and Cerebras, which did not feature existing shareholders selling stock during their IPO phases. However, other recent large technology IPOs, such as CoreWeave and Figma, did incorporate secondary sales alongside newly issued shares.

Allowing share sales would enable Anthropic's stakeholders to realize the substantial paper gains accumulated over recent years. The company's private valuation has skyrocketed from under $200 billion two years ago to $965 billion as of May this year. As Anthropic finalizes the framework for what is expected to be one of the largest listings in history, managing the monetization of holdings for both investors and employees presents a complex challenge, and these plans remain subject to change.

Another source indicated that investment banks have floated an IPO valuation range of $1.5 trillion, slightly below the $1.75 trillion valuation at which SpaceX went public. Earlier reports had suggested Anthropic's listing could reach a $2 trillion valuation, though the current pricing structure is yet to be confirmed. It remains unclear what percentage of existing shares might be sold in the IPO, nor which groups—early investors, executives, or rank-and-file employees—would be permitted to participate.

In its five years of operation, Anthropic has facilitated billions of dollars in share monetization for employees through buybacks or arranged transactions, though this scale remains far smaller than that of its established rival OpenAI. Sources say Anthropic has raised at least $130 billion to date, but its ambitious compute infrastructure plans require additional capital. The IPO's fundraising target is expected to exceed the $86 billion that SpaceX raised when it listed in June. How the company will allocate total proceeds between new share issuance and secondary sales is still undecided.

Multiple insiders report that Anthropic plans to publicly file its IPO prospectus after the U.S. Labor Day holiday, with two sources adding that an investor day for potential investors and industry analysts is slated for mid-September. Those familiar with the timeline suggest the IPO will likely occur between late September and early October, although a delay remains possible.

Alan Denenberg, a partner at Davis Polk who has managed numerous large tech IPOs, outlined several strategic reasons companies opt to permit secondary sales during the IPO phase. These include reducing the pressure of a concentrated lock-up expiration, helping employees generate cash to cover tax liabilities arising from vested equity, and maintaining control over who receives IPO shares rather than letting them trade freely on the open market. Denenberg, who does not have direct knowledge of Anthropic's internal plans, added that companies typically exercise caution in limiting insider selling, particularly among executives and investors, as the market may interpret large-scale sales as a sign that internal shareholders are cashing out rather than expressing confidence in long-term value.

Post-listing, companies generally restrict investors and employees from selling shares for a set period to prevent a flood of supply from depressing the stock price. The standard lock-up is 180 days. However, SpaceX and Cerebras adopted staggered release schedules, allowing shareholders to sell in tranches before the 180-day mark under certain conditions. Both stocks have experienced significant volatility since their debuts. During Thursday's trading session, SpaceX shares hovered slightly above their offering price, while Cerebras traded marginally below; both remain well off their post-IPO highs.

Several individuals involved in the discussions say Anthropic is considering imposing a lock-up exceeding 180 days for at least some shareholders. How share sales would be managed after the lock-up expires remains unclear. Given that Anthropic's growth trajectory is among the most volatile in business history, a longer lock-up could help manage future stock price fluctuations. Executives have acknowledged that demand for code agents and related products this year has exceeded expectations, and neither investors nor company advisors can determine whether the current high growth rate is sustainable.

Anthropic's primary backers include Spark Capital, Lightspeed Venture Partners, Iconiq, as well as Google and Amazon, the latter two also supplying cloud server resources to power its AI models. Last month, reports emerged that Anthropic is exploring another unconventional policy to govern employee stock trading after the listing: requiring ordinary staff to sell shares according to predetermined trading plans. These arrangements, known as 10b5-1 trading plans, specify the quantity of shares eligible employees may sell and the transaction price, differing from the conventional model where employees can sell freely during designated windows following earnings releases. 10b5-1 plans are typically reserved for executives and directors with access to strategic information. However, Anthropic is considering extending this mechanism to all employees, given its open internal information-sharing culture, as a means to mitigate insider trading legal risks.