Arcelor chairman Joseph Kinsch (right) shakes hands with Lakshmi Mittal, chairman and CEO of Mittal Steel, after finalising the merger of the two steel giants

Merger planning has a great deal in common with those big premarriage discussions. In both cases, each side needs to be clear-eyed about the other’s strengths and weaknesses, to find areas where the partners can work together and other areas where they could each use some personal space.

Just as couples are supposed to talk about financial expectations, companies are expected to project spending needs and growth opportunities. And, of course, there should be a discussion about whether a name change will occur.

And just as couples may fight about whether to keep or toss one person’s beloved orange sofa, merging companies too often botch their strategising about which people to retain in the combined organisation. They wait too long to start the analysis, they fail to offer appealing incentives to the people they want, and — just like a couple starting out together — they do not communicate effectively.

Managers trying to integrate newly acquired companies and divisions have their work cut out for them. Many current deals are about growth opportunities, which makes keeping key employees especially important. But when unemployment is low, that is especially hard to do.

“Once executive recruiters hear of a merger, the light bulbs start going off,” said Chris Gottlieb, a partner at KPMG who runs a group advising clients on business issues related to mergers and acquisitions. “The pressure is on the management team because that is a time when, on average, companies are vulnerable to losing people. Employees start to overthink what this merger means for them. In the first six to eight months of a deal, if a company is not good at communicating the goals, then they are at risk of losing some people.”

So what, exactly, is the best way to persuade members of the new corporate family to stay? The sensible approach is the simplest: plan ahead, communicate often and treat everyone involved in the deal with respect. Say clearly and early when any cuts will occur, and help people feel that they are a part of the combined company’s culture.

Timothy J. Galpin, a senior fellow at Katzenbach Partners and author of The Complete Guide to Mergers and Acquisitions, uses the term “re-recruiting” to describe what managers need to do after a deal. A manager must find out whether a committee assignment, a new title, a role in the transition or some other inducement might make a difference in keeping an employee. (Retention bonuses are tricky. If they are not tied to performance, Galpin said, an employee may just spend several months landing the perfect job elsewhere.)

Re-recruitment comes up most often in rapidly changing industries like technology and health care, where employees with specific skills can be particularly valuable. But not all skills are technical: it is crucial to identify the employees who form the core of the company’s social network, Galpin said, because they can help persuade valuable employees to stay. It is also important not to forget people in the acquiring company who may feel shunted aside.

“You have to look at your own people and say, ‘Who do I need to worry about on my current team?’ ” he said.

Even managers who go through all these steps will wind up losing people. A year after a deal closes, Galpin says, managers would be doing well to have retained 80 per cent of the employees they wanted to keep.

Sometimes, the people who leave after a merger or acquisition are quite senior. That is what happened at Chrysler not long after it merged with Daimler-Benz in 1998, and analysts suggested that the companies might have underestimated the cultural differences between them.

“You always have people who are going to leave for one reason or another” after a merger, said Kevin McCormick, spokesman for the Chrysler Group. He added that several of the executives who left in 1999 “had reached the zenith of their careers”, and said he thought that the companies had a good understanding of their differing cultures when they combined.

Some companies, particularly regular deal makers, become quite practiced in integrating acquisitions. IBM, which has undertaken more than 60 acquisitions in the last five years, has a small team of employees who work full time on postdeal issues, according to Randy MacDonald, global director of human resources.

Several years ago, IBM acquired a company whose leaders never really became engaged in the postmerger integration, MacDonald said, declining to identify the company. The deal never meshed, and IBM wound up selling the company.

To avoid situations like this, IBM sends a group of postmerger specialists to work at an acquired company, doing due diligence and assessing the culture of the organisation and key employees’ strengths. Then, sometime during the first 30 days after the deal closes, IBM brings in the acquired company’s managers for a discussion on the culture at IBM and how to succeed there.

Six months after the deal closes, the leaders of the acquired company return, along with leaders from other acquired companies. For several days, they provide their own perspectives on IBM’s management, leadership, products and services.

“One of the dangers in any acquisition is the acquiring company assuming their culture is the right one,” MacDonald said. “If you tell me how to make me better, you open up a dialogue. We build a bond and we build a culture.”

Kind of like a marriage.