The proposal is designed to take 75 years. The money it is meant to shore up is projected to run short in about six years.
In his 2026 annual chairman's letter, published on March 23, BlackRock (BLK) chairman Larry Fink endorsed a plan to seed an investment fund alongside the Social Security trust fund. The letter describes it plainly: “The fund would require an initial investment of roughly $1.5 trillion and would be given 75 years to grow. During that period, the Treasury would continue covering benefits. Once the fund matures, it would pay the Treasury back and supplement payroll taxes going forward.”
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Fink preempted the objection most readers will arrive with. “This would not mean privatizing Social Security or putting it all into the stock market,” he wrote. “It would mean introducing a measure of diversification, similar in principle to the federal Thrift Savings Plan, which manages retirement savings for millions of federal employees.” He has written about retirement savings before, and another Barchart contributor has covered his views on the limits of target-date funds.
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While Fink is backing the bill, the idea belongs to Senators Bill Cassidy and Tim Kaine, who set it out in a July 2025 op-ed: an additional fund “in parallel to the trust fund, not replacing it,” a “$1.5 trillion up-front investment,” and “75 years to grow.” The Thrift Savings Plan comparison is Fink's framing, and the senators invoke the TSP only as a governance model, writing of “guardrails modeled after those used by the Thrift Savings Plan.” The structural precedent they actually cite is different: “In 2001, Congress created the National Railroad Retirement Investment Trust.” That is the working analog, and it is much smaller.
The deadline the fund is racing is contested even among the official scorekeepers, and the disagreement is worth publishing rather than resolving. The Congressional Budget Office projects the Old-Age and Survivors Insurance trust fund will be exhausted in fiscal 2032 and the two funds combined in 2033. The Social Security Trustees, reporting in June 2026, put OASI depletion in the fourth quarter of 2032 and the combined funds in the third quarter of 2034. On the headline fund, they agree. On the combined figure, they differ by a full year.
They also measure the consequence differently. The Trustees frame it as a share payable: 78% of scheduled OASI benefits, and 83% for the combined funds. CBO frames it as a reduction, and in March 2026 testimony put it at 7% in 2032 and an average of 28% a year from 2033 to 2036, while noting that “the method for reducing payments is not prescribed in current law.” Barchart has covered the 2032 shortfall and the cut retirees face previously.
A fund given 75 years to compound before it repays the Treasury and begins supplementing payroll taxes does nothing for a benefit paid in 2032, 2040, or 2060. Both the senators and Fink are explicit that the Treasury carries benefits throughout the growth period, which means the proposal is a solution to the system's second century rather than to its next decade.
The letter's strongest argument is that the model already runs somewhere. “About six million state and local employees, many of them police officers, firefighters, and teachers, don't contribute to Social Security,” Fink wrote. “Instead, they rely on public pension systems that invest in diversified portfolios.” BlackRock's interest should be stated alongside it as a fact rather than a motive: the firm reported $14 trillion in assets under management as of Dec. 31, 2025, and said more than half is linked to retirement.
As of late September 2026, no bill creating this fund has been introduced. The PROMISE Act, introduced by Senator Dick Durbin in July 2026 with Cassidy and Kaine among its cosponsors, would set up an expedited path for a solvency bill produced by the Social Security Advisory Board. A separate Cassidy resolution from August 2026 would convene a bipartisan working group. Both sit in the Senate Finance Committee with no action recorded since referral, and neither creates a fund. A 75-year plan has not yet reached the stage of having a bill number, and any projection resting on 75 years of assumed returns is, by construction, an assumption that no available market record is long enough to test.
On the date of publication, Caleb Naysmith did not have (either directly or indirectly) positions in any of the securities mentioned in this article. All information and data in this article is solely for informational purposes. For more information please view the Barchart Disclosure Policy here.
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