A secondary market valuation is the price implied when existing shareholders — employees, early investors, or founders — sell their stock in a private company to other investors, rather than the company raising new money directly. It is not an official valuation set by the company’s board; it is simply whatever price a buyer and seller agree on for a small slice of stock changing hands. When AI labs like Anthropic are reported to be “worth” over a trillion dollars, that figure usually comes from this kind of trade, not from an initial public offering or an audited company filing.

How a secondary sale works

Most private companies — including nearly every major AI lab — are still privately held, meaning their stock doesn’t trade on a public exchange like the Nasdaq. Their shares are instead owned by founders, employees, and venture capital firms from earlier funding rounds. A secondary sale happens when one of those existing holders sells shares to a new buyer, often through a specialized broker or trading platform. No new cash goes to the company itself; money simply moves between the seller and the buyer, at whatever price they settle on.

This is different from a “primary” round, where the company itself issues new shares in exchange for cash that goes onto its balance sheet. Primary rounds are negotiated directly with the company, typically involve legal due diligence, and produce an official valuation the company reports. Secondary trades happen off to the side, between private parties, and the company may not even be involved in setting the price.

Why AI startups have such active secondary markets

Investor demand for shares in leading AI companies has been intense, while the number of AI labs staying private for years — rather than going public — has grown. That combination creates the conditions for an active secondary market: a lot of buyers chasing a small, fixed pool of shares that current holders are reluctant to sell.

Anthropic is a recent example. Business Insider reported that shares of the company, maker of the Claude assistant, were trading at an implied $1.2 trillion valuation on secondary platforms — more than 550% higher than a year earlier, and above the roughly $908 billion secondary price reported for OpenAI. For comparison, Anthropic’s most recent primary funding round, a Series H completed in May 2026, had valued the company at $965 billion. The gap between that official round and the secondary price shows how quickly secondary prices can run ahead of a company’s last formal valuation.

Why the number can be a “noisy signal”

Secondary valuations are useful, but they come with real caveats. Trading volume is typically thin: brokers involved in the Anthropic trades described near-total scarcity of willing sellers, meaning the handful of trades that do close can move the implied price sharply without reflecting a broad market consensus. A buyer in a secondary trade usually gets no board seat, no say in company decisions, and no guaranteed path to cash out later — unlike an investor in a primary round. And because private companies aren’t required to disclose financials the way public companies are, outside buyers are often pricing the stock on limited information, momentum, and scarcity rather than audited revenue or profit figures.

That’s why investors who track this market describe secondary prices as directional rather than definitive — a sign of where demand is heading, not a substitute for the valuation a company sets when it actually raises money or goes public.

Secondary market vs. IPO

Going public through an IPO is the other route to putting a real market price on a company’s shares — and it works very differently. An IPO involves audited financial disclosures, regulatory review, and a broad base of public buyers setting the price through open trading, which produces a valuation with far more transparency than a handful of private trades. SK Hynix’s Nasdaq debut, for instance, gave the memory-chip maker an immediate, publicly verifiable share price the day it started trading. Anthropic and OpenAI, by contrast, remain private, so a secondary market trade is currently the only real-time signal of what investors think their shares are worth.

In the news

Anthropic’s valuation reaching $1.2 trillion on secondary markets is the trade that put this concept in the headlines, overtaking OpenAI’s secondary price for the first time. Background on the company itself is in What Is Anthropic?

FAQ

Is a secondary market valuation the same as a company’s “official” valuation?
No. The official valuation comes from a primary funding round, where the company itself issues new shares to investors at an agreed price. A secondary valuation is just the price of a private trade between existing shareholders and outside buyers.

Can ordinary investors buy shares in companies like Anthropic or OpenAI on the secondary market?
Generally no. Secondary platforms for private AI companies are typically restricted to institutional or accredited investors, and the company can also restrict or approve who is allowed to buy its stock.

Why don’t companies like Anthropic and OpenAI just go public if their shares are worth so much?
Staying private lets a company avoid the disclosure requirements, quarterly earnings pressure, and regulatory scrutiny that come with a stock market listing, while still letting some early shareholders sell stakes through secondary trades.

Does a high secondary valuation mean the company is actually worth that much?
Not necessarily. It reflects what a small number of buyers were willing to pay for a scarce, illiquid stake — useful as a signal of investor sentiment, but not an audited or guaranteed figure.