The Federal Trade Commission (FTC) and Department of Justice (DOJ), which already are frustrating companies and their legal teams by taking the toughest stand against mergers since the 1970s, now are planning changes that could add months to pre-merger notification reviews. The agencies said Tuesday that they are proposing the biggest changes to the Hart-Scott-Rodino merger-filing process since 1978. That process requires pre-merger notification for deals above $111.4 million.

Previously, a 30-day waiting period sufficed for the government to review proposed transactions and determine whether they require further investigation. But under the proposed changes, companies would have to provide extensive additional information, such as acquisitions over the prior 10 years, management and board details, supplier relationships, and projected revenue streams.