People choices made before day one shape integration value

Only 16 percent of respondents in PwC's 2026 M&A Integration Survey said they had assessed leadership and talent before signing or carried out people and organizational diligence. The survey, published on September 29, draws on 530 C-suite executives and senior dealmakers at companies with annual revenue of $1 billion or more. They named clear organization design and decision rights as their leading people-related challenge, cited by 56 percent. The figures are self-reported, and PwC sells deal and integration services. Even so, they imply that most acquirers do not assess leaders and talent before signing, a habit the research below gives reason to avoid.

The most direct evidence concerns the first leadership appointments. In a study of 96 acquisitions that took place between 1980 and 1984, Albert Cannella and Donald Hambrick found that departures of acquired executives harmed post-acquisition performance, with the loss of the most senior, such as chief executives and chairmen, appearing most damaging. Giving one or more acquired executives a place on the combined firm's top management team was associated with better performance (Strategic Management Journal, 1993). The data are old and observational. They still point to a choice made early, in the first round of appointments, that is hard to reverse once the people concerned have left.

What the research shows

Departures after a deal are not random. James Walsh followed the top managers of acquired companies for five years and found turnover significantly higher than normal, with visible, very senior executives leaving sooner than less visible colleagues (Strategic Management Journal, 1988). A later study with John Ellwood found that target top-management turnover was higher than normal in the two years after a deal and was unrelated to how well the targets had performed before it (Strategic Management Journal, 1991).

Why people leave matters as much as how many. Studying 430 executives in 97 acquired firms, Hambrick and Cannella found evidence that relative standing, or local social status, helps explain which acquired executives depart (Academy of Management Journal, 1993). The mechanism reaches below the executive suite. Using patent data on 3,933 inventors at acquired pharmaceutical companies, Srikanth Paruchuri, Atul Nerkar and Hambrick found that integration generally impaired inventors' productivity, most severely for those who lost the most social status and centrality in the combined company (Organization Science, 2006). If a new structure lowers people's status or centrality, the study suggests their productivity may suffer, which makes role design a productivity decision as well as a retention one.

In 228 US bank acquisitions, Maurizio Zollo and Harbir Singh found that replacing the acquired firm's top managers hurt performance, all else being equal, while deeper integration and codified integration know-how improved it (Strategic Management Journal, 2004).

On communication, there is experimental evidence. In a field experiment by David Schweiger and Angelo DeNisi, employees at one plant of a company that had just announced a merger received a "realistic merger preview," a program of realistic communication about the merger, while employees at another plant received limited information. Across four rounds of data collection, the preview reduced the merger's dysfunctional outcomes, and the effects lasted for the duration of the study (Academy of Management Journal, 1991). With only two plants compared, the study shows what is possible rather than what is typical.

Inventors who lost the most status and centrality in the combined company suffered the steepest productivity drops.

The strongest counter-evidence

Most of these studies are archival, many use samples that are decades old, and they show associations. A departure may be a symptom of a deal going badly as much as a cause. Some exits are the point of the deal, where removing duplicate roles is the synergy.

Reviewers also question retention as a default. Jeffrey Krug, Peter Wright and Mark Kroll concluded that the link between turnover and post-acquisition performance is more complex than existing studies imply, argued that there are good theoretical grounds to think replacing executives may be an equally important source of value creation in some acquisitions, and wrote that the decision to retain or replace target executives "is largely a matter of context" (Academy of Management Perspectives, 2014). A meta-analysis of 112 studies by Tsvetomira Bilgili and colleagues found that turnover in the acquired top team and turnover of its chief executive have opposite effects on post-acquisition performance (Journal of Management, 2017). In the authors' accepted manuscript, top-team turnover is associated with worse performance and CEO turnover with better, although the CEO estimate rests on only two studies.

Cultural differences, which a substantial body of research treats as an obstacle to integration, cut both ways. A meta-analysis by Günter Stahl and Andreas Voigt of 46 studies covering 10,710 deals found that cultural differences affect sociocultural integration, synergy realization and shareholder value in different and sometimes opposing ways (Organization Science, 2008).

People decisions are also only one influence among many on how a deal performs. A meta-analysis by David King, Dan Dalton, Catherine Daily and Jeffrey Covin found that, on average, acquiring firms' performance does not improve with their acquisition activity and is modestly hurt, and that variables researchers had not identified may explain significant variance in results (Strategic Management Journal, 2004). Integration choices may be among them; the meta-analysis does not say.

Finally, "before day one" has a legal boundary. Staff of the US Federal Trade Commission wrote in 2018 that until a merger closes, the parties "must continue to operate independently," and that competitively sensitive information needed for integration planning should pass through clean teams and other safeguards. A buyer that effectively takes control of the target before closing risks what US antitrust enforcers call gun jumping. Before closing, integration leaders can plan and decide; the decisions take effect afterward.

What to settle before day one

• The top team. Name the leaders of the combined organization and decide, deal by deal, whether executives of the acquired company sit on the top team. The evidence leans toward keeping the wider top team; on the acquired chief executive it is thin and divided.
• The roles the deal depends on. Identify the roles, not just the people, that carry the investment case: the scientists, engineers, client leads and specialists it assumes will stay productive. Settle their scope, reporting lines and decision rights before designing retention packages. A retention payment keeps someone on the payroll; the role decides what they contribute.
• Retention offers that follow from the role design. Offer them to the people in those roles, with terms tied to the integration milestones that matter, and decide now how you will measure whether they work. In a self-reported 2024 study of 159 respondents by WTW, which advises on retention pay, almost 40 percent of respondents said they did not track retention rates, and only 15 percent tracked retention beyond the end of the retention agreement.
• A realistic communication plan. Tell employees what has been decided, what has not, and when the rest will be decided, and repeat it as decisions land.
• A lawful sequence. Run planning through clean teams where sensitive data is involved, settle the decisions before closing, and make them take effect at closing.