PITTSBURGH — With more than $4 trillion in global merger and acquisition activity last year, there are a lot of workers at companies being acquired asking themselves: What should I do?

"The first thing is not to panic," said Alisa Collins, president of Compass Business Solutions, a Pittsburgh-area human resources consultant. "All change is not going to be bad or negative."

Easier said than done.

"Trust me, that is not the typical response," said Gillian Florentine of EchoHR Consulting, another Pittsburgh-area firm.

She advises workers in this position not to make permanent decisions based on temporary emotions. Instead, just like the company acquiring their employer, they should perform due diligence on the new owner.

"Learn as much as you can from as many credible and reliable sources as you can," Florentine said.

What you want to learn is the acquiring company's culture, what made it interested in your employer, and what skills it values. Finding out what it did with previous acquisitions can also be important, though experts say no two acquisitions are alike.

"There could actually be growth that comes out of the acquisition. You've got to be positive and look at this as an opportunity," said Lois Bradley, president of Bradley Partnerships, a human resource consultant based outside Pittsburgh.

Bradley said she has seen situations where workers at acquired companies in low- and mid-level positions received promotions once the new owner came in.

"The biggest thing is to do everything you can to show your value to the acquirer," she said. "Demonstrate good work ethic. Do your job. Offer to help and support them. Being a good teammate is the biggest thing."

Of course, many acquisitions target saving money by eliminating redundant positions in accounting, information technology, legal, human resources and other corporate functions.

"In some cases, it doesn't matter where you are in the organization chart. If they want to clean house, they're going to clean house," Florentine said. Even if that could be the case, she said, keep putting your best foot forward and start making contingency plans.

Bradley said workers should see the sale of their employer as an opportunity to evaluate where they are in their career and where they ought to be. Knowing those things will help when it comes to networking with contacts about other opportunities, she said.

Networking and having an up-to-date résumé is something employees should have regardless, Collins said.