Irrational Escalation in M&A: Why Bidders Overpay in Real Time

The moment a company commits its first bid in an acquisition, it has already begun losing money—not because the target is overvalued, but because the bidder has entered a psychological state that makes overpayment inevitable.

This is not about information asymmetry or market conditions. It is about the mechanics of commitment. Once a board approves an initial offer, that figure becomes an anchor point not just for negotiations, but for the bidder's sense of what they have already invested in the deal. The initial bid is no longer merely a number; it becomes a public statement of intent, a signal to the market, and—critically—a sunk cost that reshapes how subsequent decisions are made.

What everyone gets wrong about M&A pricing is that they treat each new bid as a fresh calculation. Rational actors, the theory goes, should evaluate each round independently: Is the target worth this price given what we know now? But human decision-makers do not work this way. They work with reference points. The first bid creates an expectation—internally and externally—that anchors all subsequent valuations. When a competing bidder enters, the original bidder does not recalculate the target's intrinsic value. Instead, they calculate how much they have already committed and what it would cost to walk away.

This matters more than people realize because it explains why the highest bidder in a contested auction is almost always the one that will destroy shareholder value. The winner's curse in M&A is not random. It is structural. The bidder willing to pay the most is precisely the one most psychologically invested in winning—the one for whom the sunk cost of previous bids has become a form of emotional capital that must be justified.

Consider the sequence: Bidder A offers $50 per share. The board approves it. Advisors are hired. Due diligence deepens. A press release goes out. Suddenly, Bidder B enters at $55. Now Bidder A faces a choice that is no longer purely financial. They have already spent political capital internally, already made promises to their own board about synergies, already begun the process of integration planning. Walking away means admitting error. Staying in means bidding $60, then $65, each increment feeling smaller than the last because it is being measured against the previous commitment, not against the original valuation model.

The escalation is rational within this frame—but the frame itself is the problem. Each new bid feels like a marginal decision: "We're already at $60; what's another $2 per share?" But this is precisely how bidders end up paying $75 for an asset they valued at $55 six months earlier. The valuation did not change. The target did not become more valuable. What changed is the bidder's relationship to the sunk cost of their own commitment.

What actually changes when you see this clearly is that you stop treating the first bid as a preliminary offer and start treating it as a commitment device. The initial price you signal to the market is not a negotiating position—it is a psychological anchor that will constrain your rationality in every subsequent round. This is why the most disciplined acquirers set a walk-away price before any bid is made public, and then enforce it with institutional rigour, not emotional restraint.

The uncomfortable truth is that the bidder most likely to overpay is not the one with the worst information. It is the one most willing to escalate incrementally, because each step feels justified by the previous one. The auction mechanism does not reveal the target's true value. It reveals which bidder is most vulnerable to the sunk cost fallacy—and then it extracts maximum value from that vulnerability.