The Anthropic IPO and Your RSUs

I’m Mateo Dellovo, a fiduciary adviser for people paid in company stock. This page pulls together what Anthropic’s filing says about employee equity and the questions to answer before you sell.

When RSUs vest and settle in shares, the value of those shares counts as income for that year. It is taxed like pay, at ordinary income rates.

The filing ties the performance condition to the registration statement becoming effective. If many of your RSUs settle at once, all of that income lands in one tax year.

If you hold options, the tax depends on the type. With most nonqualified options, the IRS says you include in income the value of the stock at exercise, minus what you paid. With incentive stock options, exercise generally adds no regular income, but you may owe alternative minimum tax that year.

Withholding is an estimate, not your final bill. Your employer can withhold federal income tax on supplemental wages at a flat 22% in 2026. Above $1 million of supplemental wages in a year, the withholding rate is 37%. Your own tax rate can be higher than what is withheld.

If too little is withheld, you may owe the difference when you file. The IRS also says you might have to pay estimated tax during the year.

The rate Anthropic assumes is blank in the October 26 filing. Anthropic’s equity team can tell you the rate used for your shares.

A lockup keeps insiders, including employees, from selling their shares for a set period after an IPO.

Anthropic’s filing describes releases in stages rather than one date. For directors and officers who are not founders, and for certain current and former employees and consultants, up to 10% of their locked up shares can become available on the first trading day after the date of the prospectus. Up to an additional 35% can become available on the second full trading day after Anthropic releases its results for 2026. The rest become available at the earlier of the second full trading day after Anthropic releases results for the quarter ending March 31, 2027, or right after the close of trading on the 180th day after the date of the prospectus.

Certain other stockholders have their own schedules. The cofounders and certain stockholders who held more than 0.5% of Anthropic’s fully diluted shares before the IPO have a longer lockup. Some of their shares can be released along the way, and the rest at the earlier of the second full trading day after Anthropic releases results for the quarter ending September 30, 2027, or right after the close of trading on the 365th day after the date of the prospectus.

During the lockup, the filing says the company may help employees sell shares to cover the withholding taxes due when their equity awards vest or settle.

Your own release dates depend on the agreements that cover your shares. Anthropic’s equity team can confirm them.

The IPO lockup guide covers the rules that apply at every company.

After an IPO, one stock can become most of what you own. When it does, one price can move your whole plan.

At 21, I had almost everything in one stock, CMGI. I learned early how much one price can change a plan.

How much to keep is your decision. It can help to decide it on purpose rather than by default.

Even after a lockup ends, company policy can limit when employees may sell. The filing says Anthropic’s Insider Trading Policy applies to all of its officers, directors and employees, as well as designated consultants. It also describes a quarterly blackout window, when the people covered by that window may not trade.

The filing also says the company may help set up Rule 10b5-1 trading plans during the lockup, as long as no shares are sold under those plans during it, except as a lockup agreement allows.

An open window is company policy. Insider trading law applies whether a window is open or closed.

Before you sell, it can help to know three things. What was withheld, what you may owe for the year in total, and when any balance is due. Knowing those first can make the size and timing of a sale easier to decide.

1. Which of your RSUs have met their service condition, and when will they settle?
2. What rate will be withheld, what might you owe in total, and is any of it due before you file?
3. If you hold options, which type are they, and what would exercising this year do to your tax?
4. Which lockup releases cover your shares, and on which dates?
5. When does your first trading window open, and what does the policy ask of you before you sell?
6. How much of your net worth will sit in one stock, and how much do you want there?