A SPAC is a special purpose acquisition company: a shell company with no products, no revenue and no operations, that raises money in a stock-market listing for the sole purpose of buying a private business and taking it public. It is often called a blank-check company, because the people who put money in at the start are backing the team running it rather than any specific business. Understanding how a SPAC works matters because the structure hands ordinary investors a say, and some protection, that a normal listing does not.

How a SPAC is built

A SPAC starts with a sponsor, usually an investor, executive or group with a track record, who sets up the shell and takes it public through an initial public offering. Because there is no business to value yet, the shares are almost always sold at a round number, typically $10 each. For the mechanics of a conventional listing that a SPAC is an alternative to, see our guide on how an IPO works.

The cash raised goes into a trust account, usually invested in safe short-term United States government securities, where it sits while the sponsor hunts for a company to buy. The sponsor typically has a deadline, commonly around two years, to find a target and close a deal.

The merger, and the vote

When the sponsor identifies a private company, the two sides agree to combine in what is known as a de-SPAC transaction. The private company effectively takes over the SPAC's stock-market listing and becomes a public company, usually faster than it could through a traditional IPO.

Why would a private company choose this route? Speed and certainty are the usual answers. A de-SPAC can close in months and lets the target negotiate its valuation directly with one counterparty, the sponsor, rather than leaving the price to a traditional IPO roadshow. In those peak years it also let companies with little revenue and big growth projections reach public markets in a way a conventional IPO, with its tighter rules on forward-looking statements, made harder. That last point is exactly what later drew regulators in.

Here is the part that protects early investors. Before the merger closes, SPAC shareholders generally get to vote on the deal, and they have a redemption right: they can choose to get their original investment back out of the trust, plus any interest, rather than stay in for the merger. In other words, an investor who does not like the target the sponsor has picked can usually ask for their money back. If the sponsor fails to complete a deal by the deadline, the SPAC is wound up and the trust money is returned to shareholders.

Where the risks sit

The protections are real, but so are the costs, and this is where the structure has drawn criticism.

The sponsor is usually rewarded with founder shares, often around 20 percent of the company, bought for a nominal sum. That stake, known as the promote, dilutes the other shareholders and gives the sponsor a strong incentive to close almost any deal rather than return the cash and walk away with nothing. SPACs also often issue warrants, which let holders buy more shares later and dilute existing owners further. And the quality of the outcome depends heavily on the target the sponsor chooses, which investors are asked to judge on projections about a company that is not yet public.

The record from the last frenzy is sobering. A record wave of SPAC deals in 2020 and 2021 was followed by a stretch in which many companies that went public this way traded well below their $10 starting price, and a number later struggled or failed outright. The lesson is not that the structure is a scam, but that the average result depended on the specific deal, the specific sponsor and the price paid.

What the regulators changed

Regulators noticed. The Securities and Exchange Commission adopted new SPAC rules on January 24, 2024, that took effect 125 days after publication in the Federal Register. The rules require fuller disclosure of conflicts of interest, sponsor compensation and the dilution that existing shareholders face, and they tightened the rules around the financial projections that de-SPAC deals lean on. In certain cases the private target must now sign the registration statement as a co-registrant, making it legally responsible for the disclosures too.

The thrust of the changes was to make a de-SPAC look more like a traditional IPO in terms of disclosure and accountability, closing some of the gaps that let optimistic projections through in the peak years.

How to weigh one

A SPAC is a tool, not a verdict. The honest way to read one is to look at who the sponsor is and their record, how much of the trust other investors are redeeming ahead of the vote, how large the sponsor promote and the warrant overhang are, and how realistic the target's projections look next to its actual financials. High redemptions, for instance, can leave a newly public company with far less cash than the headline deal size suggested.

None of that is a recommendation to buy or avoid any SPAC or the companies they create. It is the set of questions the structure asks a reader to answer for themselves, with the redemption right as the one real piece of protection built in: if the deal does not convince you, you can usually take your money back before it closes.