Why do acquisitions fail, and how can buyers reduce the risk?

If you are thinking about buying a business, you have probably read that most acquisitions fail. It is a reasonable worry. You have spent years building what you have, and you don't want to put it at risk.

The useful question is not "do deals fail?" but "how do they fail, and could I see it coming?" Most of the reasons are specific, and most can be tested before you commit.

What does "failure" actually mean?

Headline failure rates mix up very different things. It helps to separate three:

1. Financial underperformance. The buyer does worse afterwards than similar companies that didn't buy. This is what most rigorous studies measure.
2. Integration problems. Key people leave, customers drift away, service slips, or the two businesses never work together properly.
3. Failure against the original objective. The deal completes and may even make money, but doesn't deliver what you bought it for: the new region, the skills, the customers.

The figures you see depend on which of these is being measured, and on whose deals:

• PwC found that 53% of acquirers underperformed their industry peers, on average, over the 24 months after completion (PwC, 2019). That covers mostly large, listed buyers.
• A 2024 study by Baruch Lev and Feng Gu, drawing on 40,000 acquisitions, states that 70 to 75% fail to achieve their objectives (Lev and Gu, 2024). The book excerpt does not set out exactly how "failure" was measured.
• UK research on listed buyers found that acquiring private companies produced positive returns when the deal was announced, while buying listed companies in the UK produced negative returns (Conn and others, 2005). Most UK owner-managed deals are purchases of private companies.

We found no credible study of failure rates for UK owner-managed businesses. So the honest summary is: a meaningful share of acquisitions disappoint, the exact share depends on the definition, and the evidence for large companies may not transfer neatly to yours.

How acquisitions go wrong: five risk mechanisms

1. Weak fit

The business is available, so it gets bought, even though it doesn't match what you set out to achieve. In a Bain survey of 250 executives involved in M&A, only 29% had an investment thesis (a clear statement of what they wanted to buy and why) that stood the test of time, and more than 40% had none at all (Bain, 2005). Start with what you want to buy and why, in enough detail to rule businesses out.

2. Overpayment

Paying for benefits that never arrive. McKinsey's study of 160 mergers found that almost 70% failed to achieve the revenue benefits expected (McKinsey, 2004). Competition for a business pushes prices up, and the emotional pull of a deal you have spent months on makes it hard to hold your number. See how to value a business before buying it.

3. Unverified assumptions

Profit that relies on one-off items, customers more fragile than they looked, a business that depends on the owner. Almost 60% of executives in a Bain survey attributed deal failure to due diligence that did not identify critical issues (Bain, 2020). Often the problem is not that issues were hidden, but that they were found and explained away under deal pressure.

4. Funding strain

Borrowing too much against forecasts that turn out optimistic, or a payment structure that squeezes cash just as the business needs investment. This one has less survey data behind it, but it is a familiar worry among owners: "how to get the funds" and expanding "on credit" come up again and again. See how established businesses fund acquisitions.

5. Integration capacity

Nobody has the time to bring the two businesses together. In Bain's survey of practitioners, 83% of those who had seen a deal fail pointed to integration problems as a primary cause (Bain & Company, 2024). Respondents could name more than one cause, and the surveys above overlap, so these percentages are not shares of a whole. Read more on post-acquisition integration.

Warning signs, and what to ask

Use our due diligence checklist to turn these into a full request list.

Practical safeguards

Test the rationale before you approach anyone. Write down the criteria, the reasons for buying and the walk-away points. Agree them with your co-owners or board. Our acquisition readiness planner is a quick way to check where you stand.

Check what you're really buying. Use accountants and lawyers who do acquisitions regularly. Ask them to focus on the assumptions your price depends on, not just a standard list.

Set decision checkpoints. Agree in advance the points where you will formally decide to continue, renegotiate or stop: after first meetings, before you agree the price and main terms in writing, and when the checks report.

Be willing to stop. Walking away from a deal that doesn't stack up is a good outcome, not a failure. Owners who have done it say as much. It is harder than it sounds: in a Bain survey of 250 senior managers with M&A responsibilities, a third said they had not walked away from deals despite nagging doubts (Bain, 2006). The time to act on doubts is before completion.

Plan integration early. Name who will lead it and what will not change on day one.

Know how your advisers are paid. Understand what each adviser is paid for and when, so you know where their incentives sit. Our guide to buy-side M&A adviser fees sets out the questions to ask. Good advice reduces risk. It cannot remove it, and the decision stays yours.

An illustrative scenario

This example is fictional and illustrative. It is not a client case.

A £15m engineering services business is offered a smaller competitor whose owner is retiring. The fit looks good: same customer type, a neighbouring region. The price is based on last year's profit.

The checks show last year's profit included a one-off contract, and two customers make up much of the remaining sales, both handled personally by the owner. The buyer has three choices: walk away, lower the price, or restructure it so part is paid later if those customers stay. They choose the third, ask the owner to stay on for a handover period, and name their operations director to lead the integration, with some of her current work handed to a deputy.

None of that removes the risk. It moves some of it back to the seller, and gives the buyer a clear point to check whether the key assumptions are holding.

A sensible next step

If you are weighing whether acquisition is too risky for your business right now, it helps to talk it through with someone who has been on the buying side. An Expansion Briefing is a free 30-minute call with us about what you want to buy and whether acquisition makes sense now, followed by a short written summary and a recommended next step.