Biotech M&A: Deal Spreads, Tender Offers, Buyout Playbook

Everyone screens for the next biotech takeover target. Almost nobody knows how to actually trade the deal once it’s announced. They see “acquirer to buy target at an 80% premium,” buy the stock at $74.50 against a $77 offer, and pocket a 3% spread without realizing that 3% is compensation for the deal breaking. That gap is the whole trade: the spread between a target’s trading price and the announced per-share price is the market’s live estimate of break risk.

The solution: read the deal spread as a probability, know how each structure (cash, stock, CVR) reprices, and size a post-announcement spread position like an arbitrageur instead of a lottery buyer.

Step 1: Decode the deal spread

A deal spread is the gap between the announced acquisition price and where the target trades today. When argenx agreed to buy Forte Biosciences for $77 per share all-cash in August 2026, Forte’s stock jumped toward $77 but did not close exactly there. The few percent left on the table is not free money; it is the market charging you for the odds the deal falls apart.

The math. If a target trades at $74.50 against a $77 cash offer, the spread is 3.2%. If the market is pricing a 10% chance of break, then a break costs you the difference between $74.50 and wherever the stock lands after the deal dies, often back toward the pre-announcement level. Expected value is roughly: (probability of close × small gain) minus (probability of break × large loss). A 3% spread does not compensate a 10% break probability when a break drops the stock 50%.

Rule of thumb: a wide spread (above 8-10%) means the market doubts the deal; a tight spread (1-3%) means the market expects it to close. Both are signals you can trade.

Step 2: Read the consideration structure

Cash deals are the simplest and most common in biotech. The target reprices to a few percent below the cash price and sits there until close. Risk is binary: the deal closes and you collect the spread, or it breaks and the stock craters. No acquirer-stock risk.

Stock deals exchange target shares for a fixed ratio of acquirer shares. You inherit the buyer’s price risk, so the target’s price moves every day with the acquirer’s stock. Pure-stock deals are rare in biotech because pre-revenue targets cannot stomach that volatility.

Cash plus CVR is the biotech specialty. A contingent value right (CVR) pays extra cash if a milestone hits, usually an FDA approval or a sales threshold. Lilly’s deal for Merida Biosciences, up to $2.875 billion in cash, is structured as an upfront payment plus milestone payments, the private-market cousin of a CVR. The trap: retail buyers overpay for the CVR piece. A CVR tied to an unproven Phase 2 asset is worth a fraction of its face value, and the milestone math is a probability-weighted bet, not a guaranteed kicker. If you cannot value the binary yourself, price the deal as if the CVR is worth zero.

Step 3: Know tender offer vs merger

A tender offer is an offer to buy shares directly from shareholders, followed by a squeeze-out merger for the rest. argenx’s Forte deal used this: a $77 cash tender for all outstanding shares, conditioned on a majority being tendered, then a merger converting the untendered remainder into the same $77. Tender offers close faster because they skip a full shareholder vote and proxy season.

A merger requires a shareholder vote and a proxy statement, adding weeks. The minimum-tender threshold (usually a majority, sometimes higher) is the number to watch: if too few shares tender, the deal stalls. Read the Schedule TO (acquirer’s offer) and Schedule 14D-9 (target’s response) on SEC EDGAR for the real terms, conditions, and any financing contingency.

Step 4: Track the closing conditions and timeline

Every deal carries conditions. The ones that matter in biotech:

• HSR waiting period: U.S. antitrust review under the Hart-Scott-Rodino Act. The Forte tender was conditioned on HSR expiration or termination.
• Financing condition: argenx funded Forte entirely from cash on hand, removing financing risk. A deal contingent on the buyer raising debt is real break risk.
• Regulatory and shareholder approvals: small in single-asset biotech deals, larger when product overlap is heavy.

The AZN–BMY episode shows break risk at scale. When the Financial Times reported AstraZeneca and Bristol Myers Squibb in preliminary talks over a roughly $400 billion combination, AstraZeneca stock fell as much as 9% as investors and analysts rejected the logic. Days later a source told Reuters there was “no deal” and “never was a deal to be done.” Anyone who chased a rumored premium there paid for it. Rumor is not an offer, and a denial whipsaws harder than a spread ever will.

Step 5: Position before vs after announcement

Pre-announcement is speculation, not arbitrage. You are betting a buyer shows up, which most of the time it does not. Use the 8-point M&A screen to find dislocated names, then size it like any binary: small enough that a “no talks” denial or a flat year does not hurt.

Post-announcement is a spread trade. You buy the target below the offer and wait for close, collecting a few percent for bearing break risk. This is the only version with a defined edge, which is why arbitrage funds, not directional traders, dominate it.

Common mistakes

• Buying the rumor instead of the spread. Rumor-driven pops reverse when talks are denied. The AZN–BMY “deal” erased its own premium within a week.
• Paying full price for the CVR. A milestone CVR on an unproven asset is a lottery ticket, not cash.
• Ignoring the financing condition. A deal funded by a debt raise can break if the credit market closes.
• Sizing a pre-announcement position like a spread. Pre-announcement is directional risk with no floor; a stock trading below cash still falls when the readout or the board fight goes wrong.

The checklist

1. Find the announced per-share price and the current target price; compute the spread.
2. Identify the structure: cash, stock, or cash plus CVR.
3. Read the Schedule TO and 14D-9 on SEC EDGAR for conditions.
4. Check for a financing condition and the minimum-tender threshold.
5. Value any CVR as zero unless you can do the milestone math yourself.
6. Size pre-announcement as speculation, post-announcement as a spread.

For the “which stocks get bought” screen, start with the 8-point M&A screen and the Big Pharma patent-cliff targets. For how a licensing deal differs from an outright buyout, read biotech licensing deal economics, and for the CVR-adjacent mechanics, royalty financing explained. If binary FDA risk is what scares you off a target, see how to trade FDA catalysts. Track live deal terms and premiums on the BioPharma Dive M&A tracker.