Three recent mergers are the latest in a spate of deals plagued by regulatory problems uncovered during merger reviews. Similar problems at other companies in the post-Enron era are likely holding down merger activity between competing companies, Washington attorneys say.

Valassis Communications Inc. is embroiled in a legal battle with a rival advertising firm and its target for a recently announced $1.3 billion merger over internal accounting methods. Hewlett-Packard Co. is holding its latest target, Mercury Interactive Corp., to a condition of filing its much-delayed 2005 10-K with the Securities and Exchange Commission before the computer company consummates the $4.5 million deal. Healthcare support system rivals Healthways Inc. and LifeMasters Supported SelfCare Inc. put their $307.5 million merger on hold a week ago because of a reporting error affecting one of LifeMasters’ contracts.