This blog post stresses the importance of addressing benefit and compensation issues before closing a merger or acquisition transaction:

"…the focus is on the liabilities - current and potential. Benefit and compensation programs can include, of course, retirement plans, welfare benefit plans, and non-qualiified deferred compensation plans. Some of the questions buyers will ask include:

• Is the retirement plan "qualified" for purposes of receiving tax favored treatment under the Internal Revenue Code?
  
• If the seller maintains a defined benefit plan, what is its funded status?
  
• If the seller contributes to a multi-employer, collectively bargained retirement plan, is there a withdrawal liability?
  
• Are there any welfare benefit liabilities, e..g, post-retirement medical benefits.

The due diligence process for both environmental and benefit and compensation issues can be quite involved, the results of which often dictate how the deal is structured: stock sale or asset sale."

If you are looking for more information on this subject, check out this blog post: Don't Let Benefits Issues Adversely Affect M&A ROI