Stock vs Cash Consideration in M&A: Exchange Ratios

Introduction

Every acquisition has a price and a currency. The price gets the headline. The currency, meaning whether the buyer pays in cash, in its own shares, or in some blend of the two, decides who carries the risk between the day the deal is signed and the day it closes, who pays tax and when, and how long the whole process takes.

Candidates tend to memorise that cash deals are more accretive and stop there. That is true and shallow. A banker choosing between cash and stock is weighing financing capacity against dilution, tax deferral for the seller against tax cost, and a signal about the acquirer's own share price that the market reads within minutes of the announcement.

Once stock enters the picture, a second layer of mechanics follows. The exchange ratio can be fixed or floating, a collar may sit around it, and something has to happen if the acquirer's shares fall hard before closing. This post covers how each side picks a currency, the ratio structures that follow, collars and walk-away rights with worked numbers, and how three real transactions were paid for.

Each structure allocates a different bundle of risk, tax and control, and each carries a different signalling cost.

All-cash consideration is cleanest for the seller and hardest on the buyer's balance sheet, while all-stock consideration costs no cash but hands away a permanent slice of future profit.

Large strategic deals usually land on mixed consideration because the two currencies solve different problems, and a blend lets the buyer tune each one. The mix reflects a few practical constraints:

The Case for Cash

Cash is the currency of conviction. A buyer paying cash keeps 100% of the synergies and every dollar of the target's future growth, and it tells the market it would rather spend money than shares. That is a bullish statement about its own stock, which is why cash offers often draw a better reaction from the acquirer's shareholders.

Cash also removes friction. There is no registration statement to write and no acquirer share price for the target board to underwrite, so the negotiation compresses to price and certainty of closing. The money still has to come from somewhere: balance sheet cash, a new bond or term loan, or a bridge facility taken out later. Mapping that is the job of the sources and uses schedule.

A buyer already carrying 3.5x net leverage cannot fund a transformational acquisition entirely in cash without a downgrade or an equity raise, and an equity raise is a stock deal with extra steps.

The Case for Stock

Stock is the currency of shared risk. When a buyer issues shares, the target's shareholders become its shareholders, so they keep exposure to whether the deal actually works. Where synergy delivery is genuinely uncertain, or the target's management is staying on, that alignment is worth something to both boards.

A merger of equals cannot realistically be funded in cash, and the equity currency scales with the deal in a way debt capacity never does. That is why near-equal combinations are almost always all-stock, with the governance split negotiated alongside the ratio.

The signalling cost is the catch. Issuing shares tells investors management thinks its stock is at least fairly valued, so the market often marks the acquirer down on announcement, which then reduces the value of the offer the target just accepted.

A target board receiving cash asks one question: is the price good enough. A board receiving stock has to ask two, because it is being handed an asset rather than a payment.

The first is what the shares are worth. Advisers run the acquirer through the same valuation work they would run on a fresh investment, because their shareholders will own it for years. A generous premium paid in an overvalued currency is not a generous deal, and fairness opinion providers will say so.

The second is tax. Cash is taxable at closing, while properly structured stock consideration lets holders defer the gain until they sell. For a founder with a very low basis, that deferral can outweigh several points of premium, which is why the M&A tax structuring toolkit sits underneath the consideration negotiation.

Once stock is part of the consideration, the merger agreement has to say exactly how many buyer shares each target share converts into. That single choice decides who wears the price risk for the months between signing and closing.

Exchange Ratio

The number of acquirer shares a target shareholder receives for each target share in a stock or part-stock merger. A fixed exchange ratio is written into the merger agreement and does not move with either share price. A floating exchange ratio is calculated shortly before closing so the value delivered per target share stays constant.

The Fixed Exchange Ratio Standard

In a fixed exchange ratio deal, the number is locked at signing:

Suppose the acquirer trades at $80.00, the target at $25.00, and the buyer offers a 32% premium, or $33.00 per target share. The ratio is $33.00 divided by $80.00, or 0.4125 acquirer shares per target share, and it never changes. What does change is the value it delivers:

The buyer likes this because it knows exactly how many shares it will issue and therefore its exact ownership dilution. Because the dilution math is settled on day one, the board approves a known outcome rather than a range, which is why fixed exchange ratios are the market standard in US public company stock deals.

Floating Ratios and Who Bears the Risk

A floating exchange ratio, usually called a fixed value structure, inverts this:

Now the value is locked and the share count moves. If the acquirer slides to $68.00, the ratio resets to $33.00 divided by $68.00, or 0.4853 shares. On a target with 100 million shares, that is 48.5 million new acquirer shares instead of 41.3 million, and on a 500 million share base the seller's ownership goes from 7.6% to 8.8%.

That open-ended dilution is why, as Freshfields notes in its survey of approaches to exchange ratios, uncapped floating ratios are almost never used in US public company acquisitions. Acquirers accept value protection for the seller, not an unlimited issuance obligation.

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A collar is the compromise between the two structures. It gives the target value protection inside a defined band of acquirer share prices and gives the acquirer certainty about its maximum issuance outside that band.

Collar

A provision in a stock merger agreement that limits how far the exchange ratio or the value of the stock consideration can move with the acquirer's share price. The acquirer's price is measured as a volume weighted average over a short window before closing, and the consideration adjusts only while that average sits inside the agreed band.

A Fixed Value Collar, With Numbers

The most common form protects value inside the band. Keep the earlier deal: a reference price of $80.00, consideration worth $33.00 per target share, and a symmetrical 10% band from $72.00 to $88.00. Inside the band the ratio floats so value holds at $33.00. At the two edges it stops moving:

Below $72.00 the ratio freezes at 0.4583, so a close at $65.00 delivers $29.79. Above $88.00 it freezes at 0.3750, so a close at $95.00 delivers $35.63. The seller is protected inside the band and rides the acquirer's stock outside it.

That is the structure Clearwater Analytics used to buy Enfusion. Enfusion holders were offered $11.25 per share, being $5.85 in cash plus $5.40 in Clearwater stock, and the merger registration statement on SEC EDGAR makes the stock leg a floating ratio while Clearwater's ten-day volume weighted average price sits between $25.0133 and $30.5718, fixed at 0.2159 shares below the band and 0.1766 above it. Those bounds are a symmetrical 10% either side of a reference price near $27.79.

The Fixed Exchange Ratio Collar

The mirror image fixes the ratio inside the band and lets it float outside. On the same numbers, the ratio stays at 0.4125 while the acquirer trades between $72.00 and $88.00, so delivered value ranges from $29.70 to $36.30. Only outside the band does the ratio adjust, rising to 0.4569 at a $65.00 close to hold value at $29.70, or falling to 0.3821 at $95.00 to cap it at $36.30.

The two designs answer different fears. A fixed value collar protects the seller against ordinary volatility and stops protecting in a genuine collapse. A fixed ratio collar leaves the seller exposed to ordinary volatility and steps in only at the extremes.

Walk-Away Rights and the Double Trigger

Collars limit the damage. Walk-away rights end the deal. The standard construction in US bank mergers is a double trigger: the target may terminate only if the acquirer's stock has fallen below a stated price and has also underperformed a named index by more than a stated margin.

Mercantile Bank's July 2025 agreement to acquire Eastern Michigan Financial, paying $32.32 in cash plus a fixed 0.7116 Mercantile shares per Eastern Michigan share, is a clean example. Eastern Michigan could walk if Mercantile's ten-day volume weighted average price fell below $40.54 and Mercantile underperformed the Nasdaq Bank Index by more than 17.5% over the same window; the deal closed on 31 December 2025 without the trigger firing. The second condition separates a sector-wide selloff, which the target agreed to live with, from a problem specific to the buyer.

Almost every such clause gives the acquirer a top-up right, a short window to raise the exchange ratio and keep the deal alive, which turns the walk-away into a renegotiation trigger rather than a true exit. It sits alongside the termination fee architecture governing who pays if the deal dies otherwise.

Mixed deals often let each target shareholder choose. The merger agreement fixes the aggregate split, say half cash and half stock, then offers holders a cash election, a stock election, or a default mix. Because individual elections never sort themselves into the agreed proportions, the agreement also includes proration.

Proration

The mechanism that scales back oversubscribed elections in a mixed-consideration merger so the total cash and total stock paid out match the split agreed in the merger agreement. A shareholder electing the oversubscribed currency receives part of their consideration in the other one.

Take a target with 100 million shares in a fifty-fifty deal, so the cash pool covers 50 million shares. If holders of 70 million shares elect cash and 30 million elect stock, cash is oversubscribed: each cash-electing share is satisfied 50 divided by 70, or about 71.4%, in cash and the rest in stock. Stock electors take stock in full. Clearwater's purchase of Enfusion ran this machinery around a roughly 52% cash and 48% stock target.

ConocoPhillips and Marathon Oil: Fixed Ratio, All Stock

ConocoPhillips agreed on 29 May 2024 to acquire Marathon Oil in an all-stock deal at a fixed exchange ratio of 0.2550 ConocoPhillips shares per Marathon Oil share. The announcement put enterprise value at $22.5 billion including $5.4 billion of net debt, and the premium at 14.7% to Marathon Oil's close the previous day. No collar, no election, no adjustment: Marathon Oil holders took the ratio and the price risk attached to it, and the deal closed that November.

Mars and Kellanova: All Cash

Mars agreed in August 2024 to acquire Kellanova for $83.50 per share in cash, valuing the target at roughly $35.9 billion including assumed net leverage. A private acquirer has no listed currency to offer, so cash was the only option. The deal also corrects the idea that cash always means speed: clearing all 28 required regulatory approvals took until December 2025, and the deal closed on 11 December, roughly sixteen months after signing.

Clearwater Analytics and Enfusion: Mixed, With a Collar

Clearwater announced its $1.5 billion purchase of Enfusion in January 2025 and closed it that April. The $11.25 per share consideration split into cash and stock, the stock leg carried the fixed value collar described above, and elections were prorated to the agreed mix. It also shows what happens when the band breaks. Clearwater's ten-day average came in at $23.2440, below the $25.0133 floor, so the ratio froze at 0.2159 and Enfusion holders received $10.87 per share rather than $11.25. The collar capped Clearwater's issuance exactly as designed and stopped protecting the seller exactly where it said it would.

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The traps are consistent, and most punish the same habit: reciting a rule of thumb without checking which structure is on the table.

Questions About the Choice of Currency

Why would a buyer use stock instead of cash? Rank three reasons: the deal is too large to fund with debt, the buyer wants the seller to share integration risk, and the seller's shareholders need tax deferral. Then add the honest fourth, which is that the buyer thinks its own shares are expensive. "Because it does not have the cash" is the weak answer.

Is a stock deal always more dilutive? No. An all-stock deal is accretive when the acquirer's price to earnings multiple exceeds the multiple it is effectively paying for the target's earnings, which happens regularly when a high-multiple buyer acquires a slower-growing business. The related trap is forgetting that a cash deal funded with debt carries its own drag through after-tax interest expense.

Questions About Timing and Risk

When does a collar bite? Only when the acquirer's measured average price leaves the band, and only in the direction the collar was written to cover. Inside the band, a fixed value collar simply resets the ratio and nobody notices. Candidates who describe a collar as protection against the deal breaking have confused it with a walk-away right.

Why do cash deals usually close faster? Because the buyer is not selling a security. A stock deal generally requires a registration statement on Form S-4, SEC review of it, and often an acquirer shareholder vote once the new shares reach or exceed 20% of shares outstanding under the NYSE listing rules. Antitrust review, by contrast, does not care what currency you pay in, which is why the Mars and Kellanova timeline stretched despite being all cash. How that closing gap gets priced is the foundation of merger arbitrage.

The consideration decision looks like a financing question and behaves like a risk-allocation question. Every clause that follows from it, the ratio, the collar, the walk-away trigger, the proration mechanic, exists because two boards had to agree in advance on what happens if the world moves between signing and closing.

The practical way to build fluency is to open one merger agreement. Pick a deal that interests you, find the S-4 or proxy on SEC EDGAR, and read the section headed merger consideration. It states the ratio, says whether it is fixed, describes any collar in careful arithmetic, and sets out the election and proration rules in a page or two.

Then test yourself with the question that catches most candidates: given this structure, what happens if the acquirer's stock drops 15% next month, and who absorbs it. Answer that from the terms rather than from a memorised rule and you understand deal consideration well enough for any M&A interview.