antitrust authorities had cleared Tyco International Ltd.'s planned $5.6 billion acquisition of ADT.

ADT, a burglar alarm company, said the required waiting period for review of the deal expired on Saturday with no action taken.

ADT agreed to be acquired by Tyco on March 17 after rejecting a rival bid by Western Resources Inc., a utility based in Topeka, Kansas. Tyco, based in Miami, is a diversified manufacturer that also makes home-security products.

Western Resources subsequently sued ADT, alleging that the structure of the proposed acquisition denies Western Resources and other ADT shareholders their appraisal rights under Bermuda law.