Anthropic's S-1 is filed. The planning window is shorter than it looks.

What's publicly reported

Anthropic's unusual structure: the LTBT and PBC

Most employees focus on economics. But Anthropic's corporate architecture is genuinely different from a typical startup, and it's worth understanding before the IPO changes the picture.

• Delaware Public Benefit Corporation (PBC). Anthropic's certificate of incorporation states its public benefit purpose: "the responsible development and maintenance of advanced AI for the long-term benefit of humanity." Delaware PBC law expressly permits directors to balance shareholder financial interests against that stated purpose — which means the board is not legally required to maximize returns if doing so conflicts with the mission.²
• Long-Term Benefit Trust (LTBT). The LTBT holds a special class of stock — Class T Common — whose only function is electing Anthropic directors. Trustees draw no salary, hold no equity in the company, and are selected by each other (not by shareholders). As of April 2026, LTBT-appointed directors constitute a majority of the board.²
• What this means for your equity: Your RSUs or options are ordinary common stock with normal economic rights. The LTBT's Class T shares carry no economic value — they are purely a governance mechanism. Your upside is not capped by the Trust. But the structure does mean that decisions conflicting with the stated mission can be blocked even if shareholders would prefer them — a real but mostly theoretical constraint for a company on this growth trajectory.
• Does the LTBT survive an IPO? Based on public statements, the structure is designed to persist through listing. The S-1, when public, will detail exactly how Class T stock and LTBT governance operate post-IPO. Review it before making any large selling decisions.

The hold-through-tender math: did it work?

Employees who declined the February 2026 tender at $350B and are still holding as of June 2026 have seen their paper position grow roughly 2.75× in about five months. That is an extraordinary outcome. But a few realities are worth naming:

1. Paper gains are not realized gains. Until shares actually settle at the IPO and the lockup expires, the $965B mark is a private-round price with no public market. Between now and October (and again for 180 days after), your equity is still illiquid.
2. The IPO price may differ from the Series H price. Recent AI company IPOs have priced across a wide range relative to their last private rounds. The public market sets the real number on day one.
3. The tax bill comes at settlement, not at sale. When double-trigger RSUs settle at the IPO, you owe ordinary income tax on the value that day — whether or not you sell a share. At Anthropic-scale positions, that event can generate more taxable income in one month than in a career combined. See the California section below.
4. The "I'll hold for LTCG" instinct is common — and worth examining. Long-term capital gains treatment requires holding shares for more than one year from the date they settle. RSUs that settle at the IPO become LTCG-eligible in late 2027 at the earliest. That means accepting 12-plus months of single-stock concentration risk to capture the rate differential. Model both paths; decide deliberately.

California: the real combined rate

Most Anthropic employees are in the Bay Area. California's tax treatment of equity is among the most punishing in any jurisdiction, and the difference between understanding it and ignoring it is measurable in six figures.

• RSU settlement at IPO = ordinary income. Settled RSU shares are taxed as wages in the year of settlement. The IRS supplemental withholding rate is 22% on amounts up to $1 million and 37% above — but for a material Anthropic position, the real marginal rate is 37% federal. California taxes ordinary income at up to 13.3% (for income over $1 million).³ Add 1.45% employee Medicare and the 0.9% additional Medicare surcharge on wages above $200,000, and the combined marginal rate for top-bracket Bay Area employees is approximately 52–53 cents on every dollar of settlement income.
• The withholding gap is almost always large. Supplemental withholding of 22% + California's own rate is a starting point, not the finish. For a settlement worth $1M+, the gap between withheld and owed commonly runs into the hundreds of thousands. This is not a loophole — it is a feature of how withholding is calculated, and you are responsible for the difference. Fund Q4 2026 estimated taxes (due January 15, 2027) before spending any proceeds.
• California does not tax capital gains at a lower rate. At the federal level, long-term capital gains on shares held over one year are taxed at 0%, 15%, or 20% (the 20% bracket starts above $545,500 for single filers per IRS Rev. Proc. 2025-32).⁴ California treats capital gains exactly like ordinary income — 13.3% at the top. Adding the federal 20% rate, the 3.8% Net Investment Income Tax (for MAGI above $200,000), and the 13.3% California rate, the combined top rate on long-term capital gains in California is approximately 37% — still significantly below the ~53% ordinary-income rate, but far above what employees in no-income-tax states pay.
• The practical implication: Holding shares post-lockup for over a year from the settlement date saves approximately 15–16 percentage points of tax on those gains. On $1 million of appreciation, that is roughly $150,000. On a $5M position, it exceeds $750,000. Weigh that against single-stock concentration risk for 12-plus months.

Six steps before October

1. Identify your double-trigger grants now. Most private-company RSUs require two conditions to vest: a vesting schedule (time or milestone) and a liquidity event. For RSUs with a liquidity-event trigger, the IPO is likely the trigger. Pull your grant agreements and equity portal and map which grants will settle at the IPO versus which have already settled.
2. Estimate the settlement tax bill. Shares expected to settle at the IPO × anticipated IPO price = ordinary income in the quarter the IPO closes. You won't know the exact price, but you can run scenarios. The RSU settlement tax estimator lets you model the federal gap and quarterly payment using your own numbers. For California employees, add 13.3% to whatever the calculator shows.
3. Review your estimated tax payments. If you're an Anthropic employee expecting a large settlement in Q4 2026 (October–December), your September 16 estimated payment (for Q3) likely doesn't capture it — but the January 15, 2027 payment (for Q4) will need to cover a substantial share of the bill. Underpayment penalties are real; fund them before they accrue.
4. Decide your concentration target before you can sell. During the lockup period, you cannot sell — but you can decide. What percentage of your total net worth is the right amount to hold in a single volatile public stock? Write it down now, as a policy, so that when the lockup lifts you execute on a rule rather than on whatever the stock has done that week. Advisors commonly recommend 10–25% as a long-run ceiling; your right number depends on age, other assets, income, and risk tolerance.
5. Read the S-1 when it goes public — especially the lockup terms. Modern IPOs increasingly use staggered lockup structures with multiple unlock windows (as SpaceX did in June 2026). The Anthropic S-1 will specify exact terms: uniform 180-day lockup, tranche-by-tranche schedule, or early-release triggers. Understand your schedule before it starts running.
6. Assess whether a 10b5-1 plan applies. If you'll have material nonpublic information windows post-IPO (typical for director-level employees, finance, legal, and product leadership), you'll need to sell during open windows or use a 10b5-1 plan. A plan adopted during the lockup — after you no longer hold MNPI — lets you pre-commit a selling schedule. The 2023 SEC amendments require a 30-day cooling-off period for non-officers; officers face a longer cooling-off. The 10b5-1 guide has the current rules.

Not an employee — want to invest?

Anthropic is private; there is no public ticker. Accredited investors sometimes access private secondary markets through specialized funds, but those arrangements carry their own transfer restrictions, fees, and information asymmetries. We don't sell or arrange investments. This page is for employees and holders planning equity they already have. Once Anthropic lists, the stock will trade on Nasdaq under a ticker to be announced.

October is closer than it looks. Get the plan built now.

Get matched with a fee-only fiduciary who works IPO equity events — settlement tax modeling, California estimated payment planning, lockup glidepath design, and 10b5-1 setup. Free, no obligation. If your window is short, say so.