Anthropic, readying an initial public offering that investors reportedly value at $1.5 trillion to $2 trillion said it will commit 5 percent of its shares, subject to shareholder approval, to a new Public Benefit Fund, with up to 2 percent more for every 50 percent gain in the company’s value. With earlier pledges, roughly a fifth of the company is earmarked for the public good.

Elon Musk’s response: Give the shares directly to the public. On Oct. 19, he pledged to do it himself: one SpaceX share, currently worth about $146, to every American child next year.

He is closer to right than he knows. The country already has an institution that insures nearly every worker against lost earnings and pays those workers directly: Social Security. But Social Security is not allowed to own equity shares; by law it may hold only federal debt.

Congress should build an independent fund that accepts contributed equity from any company, holds it in a diversified portfolio and dedicates the returns to the trust funds. Canada’s pension plan, Norway’s oil fund, Alaska’s Permanent Fund and state pension systems own equity on the public’s behalf. To allay any fears, the fund’s governance should be boring by design, with no government board seats, no political direction and a published schedule for selling each stock down into a broad index.

Anthropic and Musk are not alone in wanting the public to share in AI’s gains. OpenAI’s April policy paper proposed a public wealth fund investing in AI companies and paying returns to citizens. In July, the Financial Times reported Sam Altman had offered 5 percent of the company’s equity to seed a sovereign wealth fund. Politicians from President Trump to Sen. Bernie Sanders (I-Vt.) have called for public investment funds.

None of these has produced a working fund. Social Security, by contrast, is up and running. It covers nearly every American worker and ended last year with $2.6 trillion in reserves, all in special-issue Treasuries. But it is underpowered and shrinking. The Trustees project the retirement trust fund will run out in late 2032, when benefits would be cut 22 percent.

To be clear, AI equity pledges alone are not a sufficient funding fix. Anthropic’s 5 percent is worth $75 billion to $100 billion, and OpenAI’s offer about $60 billion, at reported valuations. The program’s 75-year shortfall is $29 trillion in present value.

But equities belong in Social Security’s portfolio, as in any retirement account. A diversified fund earning 2.5 to 3 points a year over Treasuries (within the range Social Security’s own actuaries assume), with returns reinvested, could turn every $100 billion contributed today into $600 billion to nearly $900 billion in present value over the Trustees’ window.

Sens. Bill Cassidy (R-La.) and Tim Kaine (D-Va.) have a plan to borrow $1.5 trillion to seed a Social Security investment fund. We share their aim of higher returns, but borrowing creates financing risks. The debt comes due whatever markets do, and the new borrowing would pile onto a growing federal debt just as long-term Treasury yields have hit their highest level since 2002.

Contribute the money instead, and those financing risks disappear. The same sum could close a third to nearly half the gap, shrinking the tax increases and benefit cuts otherwise needed.

AI shares should be the catalyst for larger funding sources, starting with existing federal assets. Treasury holds a senior stake in Fannie Mae and Freddie Mac that J.P. Morgan estimates will reach roughly $400 billion by year-end, plus warrants for nearly 80 percent of their common shares. Officials have proposed selling slivers while keeping the companies in conservatorship.

The government’s 261 million ounces of gold are worth about $1.1 trillion at recent prices and earn no yield.

Together that is about $1.5 trillion, what Cassidy and Kaine want to borrow, before counting a single AI share or warrant.

Washington already allows donated corporate stock in a federal program. Last year Congress created Trump Accounts for children and Treasury now lets companies and charities donate public stock into them. If a child’s account can hold donated stock, so should the program that pays 71 million Americans today and nearly all the rest of us when we retire.

The companies’ offer can be made conditional on Congress acting, a long-standing tactic in American philanthropy. Andrew Carnegie paid for nearly 1,700 public library buildings, but only in towns that supplied the land and committed public money to run them. Here, it would give Congress something to say yes to: neither a tax increase nor a benefit cut.

Anthropic says it will share more about its fund’s governance in the coming months. The company can commit now to contributing if Congress builds the vehicle. Congress can build it as part of any solvency deal, or on its own.

Social Security was the institutional answer to a great economic dislocation. The companies most confident that another is coming have begun, voluntarily, to put equity on the table. The public should have an account to receive it. The first companies to contribute will have done for this century what Carnegie did for the public library.

Eftychis Gregos-Mourginakis is co-founder of Kibu, Inc. Jan Jaro is an investor at Helena and an advisor at the Federation of American Scientists.