The Trillion-Dollar IPO and Your Index Fund

What Anthropic’s S-1 shows

Anthropic, PBC filed a registration statement on Form S-1 with the SEC on October 26, 2026, for a proposed IPO of Class A common stock on the Nasdaq Global Select Market under the ticker “ANT.” The share count and price range had not been set when it was filed.

Source: Anthropic, PBC Form S-1, summary consolidated financial data. Dashes mark figures not reviewed for this article.

Revenue grew about 14x year over year. First-half revenue went from $1.16 billion to $16.3 billion, an increase of roughly 1,300%.

Most of the loss is a valuation adjustment, not operations. About $72.4 billion of the $80.7 billion net loss came from an increase in the fair value of outstanding convertible promissory notes and similar instruments. In plain terms, when a company’s estimated value rises, the accounting value of notes that convert into its stock rises with it, and that increase is recorded as a loss. The operating loss was $693 million, and Forbes reports a $974 million operating profit in the second quarter alone. A separate $8.8 billion in other expense is not explained in the summary data.

Control sits with insiders and a trust. The S-1 describes five share classes:

• Class A (offered to the public): one vote per share.
• Class F: held by a founder entity, with 50.1% of total voting power.
• Class T: elects directors who make up a board majority. These directors are generally chosen by the Long-Term Benefit Trust, which has five financially disinterested trustees.
• Class N and Class E: carry limited or no voting rights.

Public shareholders will own economic interest but limited control.

Disclosed risks are unusual in kind. Reporting on the filing highlights the following:

• Customer concentration: about one-fifth of revenue came from two customers, and about 48% of first-half revenue came through cloud marketplaces.
• Very large computing commitments, reported at $430 billion to more than $500 billion depending on which agreements are counted. Not all of it is an immediate cash obligation.
• A U.S. export-control directive.
• A Department of Defense supply-chain designation, which the company is contesting in court.
• The possibility that its AI models could cause real-world harm or develop capabilities the company did not anticipate.

The balance sheet is strong for now. Forbes reports about $131.7 billion in cash, cash equivalents and short-term investments at the end of June 2026.

The valuation question

The filing does not state a valuation. Coverage of the filing puts the discussed range at $1.5 to $2 trillion. Treat every valuation figure below as reported, not disclosed, until a price range appears in an amended S-1.

What the multiple means. At 46x to 61x annualized revenue, the price assumes years of very fast growth ahead. Doubling first-half revenue is a rough proxy; it ignores both continued growth and any slowdown.

Who has already captured the gain. Reported private valuations rose from about $350 billion in early 2026 to $965 billion months later. Strategic investors hold large stakes; Fortune reports Amazon invested about $13 billion with up to $20 billion more committed, and Google holds roughly 14% of the equity. Much of the step-up in value happened before public investors had access.

None of this says the stock is overpriced or underpriced. It says the starting point for public shareholders is already very high.

How the IPO market changed

U.S. companies now go public later in life. The median company that went public from 2001 to 2025 was 11 years old, compared with 8 in the 1980s and 5 during the 1999–2000 dot-com boom.

Large pools of private capital help explain the shift. Sovereign wealth funds, large venture and growth funds, and strategic corporate partners can now fund companies through stages that once required an IPO. Anthropic reports raising $141.1 billion before filing.

Age is only part of the story. Anthropic was founded in 2021, so it is young for a 2026 IPO. SpaceX was founded in 2002 and listed after more than two decades. What the two share is size: both reached valuations near or above $1 trillion while still private. Most of the value creation happened before public investors could buy in.

A principle worth writing down: the size of a valuation tells you how much conviction the market has. It tells you nothing about how much of the outcome is still left to capture.

How new giants enter index funds

Index funds buy what their index holds. In 2026, some major indexes changed their rules so that very large new listings get in within weeks instead of a year. SpaceX was the first test. It priced its IPO at $135 a share on June 11, 2026, an implied value of about $1.77 trillion, and began trading on Nasdaq as SPCX on June 12.

What it implies for Anthropic. If Anthropic lists on Nasdaq at a value anywhere near reported levels, it would likely follow SpaceX into the CRSP, Russell, MSCI and Nasdaq-100 indexes within weeks. It would not qualify for the S&P 500 while it reports net losses, or before 12 months of trading. Vanguard’s own commentary names Anthropic and OpenAI as the next large IPOs that index funds should expect.

Why this matters. Many total-market index funds track the CRSP US Total Market Index, and many target-date funds hold total-market funds. A dentist in one of those funds could own a new trillion-dollar listing within a week of its first trade, without making a decision to buy it.

The starting weight is small. Indexes weight companies by float, meaning only the shares available to the public. Only about 5% of SpaceX’s shares were floated at the IPO, so it began at about 0.30% or less of most index funds. That weight can grow as insiders sell and more shares trade publicly, if the price holds.

An S&P 500 fund works differently. Its earnings and seasoning screens keep out unprofitable new listings, so it would not hold Anthropic at the start.

Neither approach is right or wrong. They are different rules, and most investors don’t know which one their fund follows.

What it means for a dentist’s retirement plan

The practical question isn’t whether to buy Anthropic. It’s whether you know what your retirement accounts already own, and whether that still fits your plan.

Three things make this especially relevant for practice owners.

• Concentration on two fronts. Many owners already have most of their net worth in one illiquid business. A new listing enters an index fund at a small weight, but a handful of very large technology and AI-related companies already make up a meaningful share of broad U.S. indexes. Adding more of them can increase how concentrated your liquid portfolio is, on top of the practice.
• Plan design shapes exposure. As the plan sponsor, a practice owner picks the fund lineup and default investment for every employee. Those choices decide which index each participant follows, which matters more now that index rules differ on how fast new listings come in.
• Time horizon changes the answer. A 35-year-old associate and a 62-year-old owner a few years from selling can hold the same fund and face very different risks. Volatility from newly listed mega-caps hits harder when withdrawals are close.

Questions worth answering:

In many cases, owning these companies inside a broad index fund is a reasonable outcome. The aim is to get there on purpose, knowing what you own and why, rather than by default.