This is general information, not investment advice.

"M&A" is one of the most consequential — and most overhyped — activities in business. Here's what actually happens, and why most deals disappoint.

Merger or acquisition?

They're different. An acquisition is one company buying another and absorbing it — the buyer survives, the target becomes part of it. A merger is two companies combining into one new entity, in theory as equals. In practice the line is blurred on purpose: many deals are sold as a "merger of equals" when one side is plainly buying the other, because the framing softens the message for employees and shareholders. Usually one party ends up owning more than half and running the combined company — legally an acquisition, whatever the press release says (per Corporate Finance Institute). The $164 billion AOL–Time Warner "merger of equals" in 2000 is the classic cautionary tale.

Three types

  • Horizontal: buying a direct competitor — for scale and market share. Draws the heaviest antitrust scrutiny.
  • Vertical: buying a supplier or distributor in your own supply chain — for control of cost and supply.
  • Conglomerate: buying an unrelated business, usually justified as diversification — now largely out of favor, since investors can diversify themselves.

How deals are paid for — and the premium

Acquirers pay in cash, stock (issuing their own shares to swap for the target's), or a mix. A cash deal hints the buyer thinks its stock is fairly valued; a stock deal can hint the opposite. And acquirers almost never pay the market price — they pay a premium over the target's pre-announcement price, commonly a median of 25–30% (most deals 10–50%). Microsoft paid roughly a 50% premium for LinkedIn.

The premium is justified by synergies — gains the combined firm is meant to produce. Cost synergies come from cutting duplication (two finance teams become one). Revenue synergies (cross-selling, new markets) are far harder to achieve and routinely overstated in deal decks.

The process

A big deal runs for months: strategy/targeting, a private approach and negotiation (often a non-binding letter of intent), due diligence (combing the target's books, contracts, litigation and customers — where hidden problems surface and deals collapse or get repriced), a binding definitive agreement (with a banker's "fairness opinion"), board and shareholder approvals, regulatory review, and finally closing.

Antitrust: who can block a deal

Large US deals must be reported before closing (under Hart-Scott-Rodino), and the FTC and DOJ — the European Commission in Europe — can clear them, force divestitures, or sue to block, per the FTC. Recent years saw real bite: Kroger's $25 billion bid for Albertsons was blocked in late 2024; JetBlue's $3.8 billion purchase of Spirit was blocked in early 2024; and Adobe abandoned its $20 billion Figma deal under regulatory pressure in 2023. Regulators don't always win — the FTC lost its challenge to Microsoft's $69 billion Activision Blizzard deal, which closed in 2023.

Friendly vs. hostile

Most deals are friendly — the target's board recommends them. A hostile takeover bypasses management to appeal directly to shareholders, via a tender offer (a public bid to buy shares directly, at a premium) or a proxy fight (soliciting votes to replace the board). The best-known defense is the poison pill (a shareholder rights plan): when a hostile buyer crosses a set ownership threshold — Twitter set 15% against Elon Musk in 2022 — every other shareholder can buy more shares at a steep discount, flooding the market and making the takeover prohibitively expensive. Pills rarely block a deal outright; they force the bidder to negotiate.

Do most deals work? Mostly not

The research is sobering. Harvard Business Review, synthesizing the literature, notes studies put the M&A failure rate at 70–90%. A 1999 KPMG study found 83% of deals failed to add value; McKinsey found ~70% missed their revenue-synergy targets. The pattern: target shareholders do well (shares jump toward the offer), but acquirer shares often fall on announcement — a sign the market doubts the logic or fears overpayment. Synergies get overestimated, integration costs underestimated, and culture clashes underweighted, often amplified by overconfidence and bidding wars.

Why companies keep doing it — and what it means

Despite the record, deal volume stays huge: firms chase scale, market entry, technology and talent (tech "acqui-hires"), or simply removing a competitor — and cash-rich boards feel pressure to act. Banks advising both sides earn a success fee, typically 1–3% of deal value, payable only if it closes — hundreds of millions on a megadeal. For target investors, shares usually rise toward the offer; for acquirer investors, they often dip. For employees, the "synergies" on the slides frequently mean job cuts as duplicate roles are eliminated. For customers, horizontal consolidation can mean less competition and higher prices — or, occasionally, better products. The lesson of the research: a deal's strategic logic on paper is no guarantee it pays off in practice.