💸 Special Purpose Acquisition Company (SPAC) Merger Model

SPAC Structure & the Trust Account Clock

A Special Purpose Acquisition Company is a publicly listed shell — no products, no revenue, no operations — whose sole purpose is to raise cash in an IPO and use it to merge with a private operating company, taking that company public without a traditional IPO roadshow. Understanding SPAC mechanics starts with understanding the two things that make it a "blank check": the trust account, and the clock.

• $150M–$400M: Typical SPAC trust size (held in short-term treasuries)
• 18–24 mo: Charter deadline window (to find & close a deal)
• ~20%: Sponsor promote (of SPAC founder shares, nominal cost)
• $10.00: Standard SPAC unit price (public IPO unit price)

What a SPAC actually is: a shell with a clock

A SPAC IPO sells "units" (typically $10 each, bundling a common share plus a fraction of a warrant) to public investors. Unlike an operating-company IPO, essentially all of the net proceeds — commonly around 100% of the trust deposit — are placed into an interest-bearing trust account, usually invested in short-duration U.S. Treasuries, and held untouched until either a merger closes or the SPAC liquidates.

The SPAC's charter imposes a hard deadline — typically 18 to 24 months from IPO, sometimes extendable by shareholder vote — to identify a target and complete a "business combination." If no deal closes in time, the SPAC must liquidate: the trust is returned to public shareholders on a pro-rata basis, and the sponsor's at-risk capital and promote shares are typically wiped out entirely.

This structure inverts the normal IPO sequence. A traditional biotech IPO prices shares against a known company with disclosed financials; a SPAC IPO prices a blank check against a sponsor team's reputation and stated intent to find a good deal — the actual target is identified only later, in a separate step this simulator walks through next.

Sponsor economics and the "promote" incentive

Sponsors typically receive founder shares — commonly amounting to 20% of the SPAC's total post-IPO share count — for a nominal purchase price, plus warrants purchased in a concurrent private placement that helps fund the SPAC's operating expenses before a deal closes. This "promote" is the sponsor's primary economic reward for finding and closing a deal.

The incentive structure this creates is important to understand: because the promote and the sponsor's at-risk capital are forfeited if no deal closes by the deadline, sponsors are economically motivated to complete a transaction — almost any reasonable transaction — rather than let the clock run out and return cash to investors. Critics have long argued this creates pressure to close deals on aggressive terms as a SPAC nears its deadline, a dynamic public-market investors should weigh when assessing why a particular target was chosen.

The trust account is not simply idle cash — it typically must maintain enough value to cover a fixed per-share redemption price (commonly around $10.00 plus accrued interest) for any shareholder who elects to redeem, which is the mechanism explored in Stage 4.

Target Selection & the Business Combination Agreement

Once a sponsor team identifies a private biotech it believes is ready for the public markets, the two sides negotiate a Business Combination Agreement (BCA) — the legal document that fixes the target's enterprise valuation, the exchange mechanics, and the resulting ownership split of the combined, newly public company.

• $700M: Illustrative target EV (this sim) (negotiated, not market-tested)
• Common closing term: Typical minimum-cash condition (protects target from a bare deal)
• Permitted: Projections in merger proxy (under PSLRA safe harbor)
• ~4–8 mo: Signing-to-closing timeline (incl. SEC proxy review, vote)

Negotiated valuation instead of market price discovery

In a traditional IPO, a company's valuation emerges from a multi-week roadshow in which underwriters gauge real-time institutional demand and build the offer price from an order book — a process that, whatever its flaws, reflects broad market feedback before the first public trade. In a SPAC merger, the enterprise valuation is instead a bilateral negotiation between the sponsor and the target's board, set before the transaction is ever exposed to public market pricing.

This has a real advantage for early-stage or clinical-stage biotechs: negotiated valuation lets a company with a promising but hard-to-price pipeline avoid the risk of a roadshow landing well below expectations. It also has a well-documented drawback — because the price is not market-tested until after the deal is announced (and, crucially, after the shareholder redemption decision described in Stage 4), it can turn out to be significantly higher than what public investors are ultimately willing to pay to hold the stock.

Ownership split mechanics

At signing, the BCA sets out how newco shares will be allocated: target shareholders typically exchange their private equity for a fixed number of newco shares (rolling 100% of their equity into the combined company at the negotiated valuation), while the SPAC's existing public shareholders and the sponsor retain their proportional slice of the SPAC's outstanding shares, subject to however many public shares are ultimately redeemed for cash before closing.

Because the redemption outcome is unknown at signing, the ownership percentages announced alongside the deal are necessarily provisional — they typically illustrate a "no redemption" or an assumed-redemption scenario, not a guarantee. This is one of the most consequential and least understood aspects of SPAC deal announcements for public-market observers.

A deal announced with an $700M target valuation and a "$300M trust" does not mean the combined company will actually receive $300M in cash — that only happens if zero shareholders redeem, which, as later stages show, has become the exception rather than the rule.

Traditional IPO vs. SPAC merger — key structural differences

PIPE Financing — Buying Certainty Alongside the Trust

Because the amount of trust cash that will actually survive to closing is unknown at signing, SPAC deals are very commonly paired with a Private Investment in Public Equity (PIPE) round — a block of newco shares sold directly to institutional investors, negotiated and committed to concurrently with the merger announcement, to guarantee a minimum amount of incremental capital regardless of what happens at the shareholder vote.

• $0–150M: Illustrative PIPE range (this sim) (slider-adjustable)
• ~$10.00/share: Typical PIPE pricing (same reference price as trust)
• Institutional, crossover funds: Typical PIPE investors (often existing target investors)
• Concurrent with BCA: Announcement timing (signals deal conviction)

Why a trust account alone often isn't enough

Two separate uncertainties motivate a PIPE. First, target companies often negotiate a "minimum cash condition" into the BCA — a contractual floor below which the target can walk away from the deal, precisely because a merger that closes with too little cash may leave the newly public company unable to fund its stated business plan (e.g., its next clinical trial readout). Second, because redemptions are unpredictable and, in practice, frequently high (see Stage 4), the sponsor and target need a source of capital that does not evaporate the way trust cash can.

A PIPE solves both problems: it is a firm, committed investment — typically documented in a securities purchase agreement signed alongside the BCA — that closes concurrently with the merger regardless of how the redemption vote turns out. PIPE shares are usually priced at the same reference price as the SPAC's public shares (commonly around $10.00), sometimes with additional inducements such as warrant coverage or a modest discount to compensate investors for committing capital before the deal's ultimate cash position is known.

PIPE size as a market signal

Because PIPE investors are typically sophisticated institutions conducting real diligence on the target before committing capital, the size and quality of a PIPE round is often read by public-market observers as an independent, semi-market-tested signal of conviction in the deal — closer in spirit to the institutional book-building of a traditional IPO than anything else in the SPAC process.

A large, well-subscribed PIPE from recognizable healthcare-focused institutional investors can meaningfully offset concerns about high redemptions; conversely, a token or absent PIPE is often read as a warning sign about the deal's underlying institutional support. Still, even a strong PIPE is usually calibrated to backstop a specific minimum-cash scenario — it is not designed to fully replace trust proceeds lost to a very high redemption rate, only to keep the deal above its contractual floor.

A PIPE is a fixed dollar commitment negotiated before the redemption outcome is known — it reduces, but does not eliminate, the deal's exposure to the redemption uncertainty explored in the next stage.

Redemption Rights — Where Headline Deal Size Meets Reality

Public SPAC shareholders have a right that is easy to underappreciate until you see its effect: independent of how they vote on the merger itself, each shareholder can individually elect to redeem their shares for a pro-rata portion of the trust account in cash rather than roll into the combined company. Since roughly 2021, redemption rates across the SPAC market have often been very high — frequently leaving deals with far less actual cash than the headline trust size suggested.

• 30%–95%+: Observed redemption range (wide variance deal to deal)
• ~$10.00 + accrued interest: Redemption price (pro-rata trust value per share)
• ~2 business days: Redemption election deadline (before the shareholder vote)
• Decoupled: Vote vs. redemption (a "yes" voter can still redeem)

The redemption mechanic — and why it's decoupled from the vote

Ahead of the shareholder vote on a proposed merger, each public shareholder receives a proxy statement and an independent election: redeem shares for cash, or hold them and roll into the combined company. Critically, a shareholder can vote in favor of the merger and still redeem their own shares — the two decisions are legally and mechanically separate. This means the merger can be approved by a comfortable majority vote while, simultaneously, the large majority of public shares are redeemed for cash and never actually convert into newco stock.

Redemption pays a fixed per-share amount — the shareholder's pro-rata slice of the trust, typically close to the original $10.00 unit price plus whatever interest the trust has accrued — regardless of what the market thinks the combined company's shares are worth. This creates a simple, low-risk arbitrage: because SPAC public shares often trade close to their redemption value in the market, many holders (including specialized arbitrage funds that acquire shares specifically for this purpose) treat the shares as a near-riskless instrument, buying pre-vote and redeeming near closing rather than taking the equity risk of the merged company.

Why redemption rates rose so sharply across the SPAC market

In the SPAC boom of 2020–2021, redemption rates on many deals were low, and headline trust sizes translated fairly reliably into actual deal proceeds. Beginning around 2021 and continuing through the following years, market conditions shifted — rising interest rates made the "redeem for cash plus trust interest" option more attractive relative to uncertain equity upside, de-SPAC share prices frequently traded below $10 post-merger, and a large base of arbitrage-oriented holders had accumulated in the SPAC market specifically to capture the redemption option rather than to hold the combined company's stock. Against that backdrop, high redemption rates — frequently well above half of outstanding public shares, and in a meaningful share of deals extending toward the high end of the observed range — became a widely documented, persistent pattern rather than an occasional occurrence.

This pattern is precisely why later-vintage SPAC deals lean so heavily on PIPE financing and contractual minimum-cash conditions (Stage 3): sponsors and targets learned to plan for high redemptions as the base case rather than the tail risk.

Because the vote and the redemption election are decoupled, a merger can be approved by shareholders while, at the same time, the deal receives only a small fraction of the trust's headline value — the two outcomes are not in tension, and both routinely happen in the same transaction.

Combined-Company Capitalization After the Redemption Gap

When the merger closes, the resulting "de-SPAC" public company's capitalization table reflects four groups: the original target shareholders, the sponsor's promote shares, the PIPE investors, and whatever public SPAC shareholders chose not to redeem. The cash the company actually has to run its business is the sum of PIPE proceeds plus only the non-redeemed portion of the trust — a figure that, for many deals, has landed far below the originally announced trust size.

• 4 groups: Cap table components (target, sponsor, PIPE, remaining public)
• PIPE + (1−redemption%)×Trust: Net cash formula (the figure that actually funds the company)
• Follow-on financing need: Common post-close outcome (when net cash falls short of plan)
• Sharply lower: Biotech SPAC volume vs. 2021 peak (reliability concerns reduced use of the path)

Reading the final cap table

At closing, target shareholders typically hold the largest slice, reflecting the negotiated enterprise value converted into newco shares. Sponsor promote shares (from the original 20% founder allocation, now diluted down as a share of the larger combined company) represent a smaller but often still meaningful slice, usually subject to lock-ups and sometimes to price-based vesting triggers negotiated to align sponsor incentives with post-close performance. PIPE investors hold shares proportional to their committed investment, priced at the deal reference price. The remaining public SPAC shareholders — those who did not redeem — hold whatever is left, a slice that shrinks directly as the redemption rate rises.

The practical consequence is that a deal announced with an ownership split assuming low or no redemptions can look meaningfully different in the finished cap table: the "public float" contributed by original SPAC IPO investors can end up a small fraction of what was originally illustrated, with PIPE investors and target shareholders making up a correspondingly larger share of the combined company's ownership and, often, its near-term trading dynamics.

The cash gap and its downstream effects

The single most consequential number for a newly de-SPAC'd biotech is not the announced trust size — it is net cash actually delivered to the company: PIPE proceeds plus whatever trust cash survived redemptions, net of transaction expenses. When this figure comes in well below the plan assumed in the original investor presentation, the company can face an unplanned choice between raising follow-on capital sooner than intended (often at a depressed post-de-SPAC share price, meaning painful dilution), slowing its clinical or commercial plans, or both.

This dynamic is a central reason the SPAC path lost favor as a public-listing route for biotechs through the years following the 2021 boom: a traditional IPO's underwritten proceeds are close to guaranteed once priced, while a SPAC merger's proceeds remained genuinely uncertain until the redemption deadline, days before closing. For a capital-intensive biotech planning a specific runway around a specific data readout, that uncertainty made the SPAC route a structurally less reliable way to reach the public markets than it first appeared at announcement.

The gap between "Announced Trust Size" and "Actual Net Cash Delivered" is the single most important number to check on any completed de-SPAC transaction — and, as this simulator shows, it can be a large fraction of the headline figure.