agreed to terminate a proposed $5 billion merger of the two home and commercial security alarm companies. The transaction would have created the largest security company in the US.

The value of the stock transaction, originally pegged at $5 billion, has declined sharply since it was announced in July.

"Despite both companies' initial enthusiasm about this transaction, we now have agreed that this combination is no longer in the best interests of our respective companies,'' Republic Chairman Wayne Huizenga said in a statement.

Bermuda resident Michael DeGroote is Republic's largest shareholder. The Canadian also holds some shares in ADT.

Failure to come to terms is the first blow to Republic chairman and chief executive H. Wayne Huizenga's plans to create a mammoth company with interests in security, garbage collection and used-car superstores, Bloomberg Business News reported yesterday.

Mr. Huizenga engineered more than 30 acquisitions since taking over the garbage-hauling company a little more than a year ago.

His biggest move came when Republic, which is based in Fort Lauderdale, Florida, agreed on July 1 to buy ADT for $5 billion in stock and assumed debt.

"We will now be able to complete several other pending acquisitions, including Addington Resources, Continental Waste and AutoNation. We will also be able to pursue a number of other opportunities which have been delayed due to the ADT transaction,'' said Huizenga.

ADT chairman and CEO Michael Ashcroft said: "The delay in completing the transaction forced both companies to put business expansion plans on hold for too long.'' He also said that both companies can now resume their individual business plans.

Under the terms of the agreement, ADT holders would have received 0.92857 share of Republic common stock for each of their shares.

Republic's stock, however, fell as much as 29.6 percent, to 20.75 from 29.50 the day before the acquisition was announced. The price has recovered some to Friday's close of 27.25.

Still, investors and analysts said Republic would have to adjust the exchange ratio to at least a one-to-one trade for the acquisition to go through.

The transaction also faced opposition from Topeka, Kansas-based utility Western Resources Inc., which owns a 24 percent stake in ADT.

Republic said yesterday it will continue to hold its warrant to acquire 15 million shares of ADT at an exercise price of $20 a share. The warrant becomes exercisable six months after the termination.

ADT is the largest provider of electronic security services in North America and the second largest vehicle auction services provider the US.

Separately, Republic Environmental Systems, Inc., a spin-off of Republic, said its information statement on the merger of Republic Environmental with the Century Surety Group and Commercial Surety Agency and the purchase by Mr.

DeGroote and Mr. Huizenga of four million shares for $10.5 million and 12 million warrants for $38.5 million was cleared with the Securities and Exchange Commission and mailed to stockholders on Thursday.

Mr. DeGroote, chairman of Republic Environmental, said the transactions are expected to close by month's end.

At closing, the company will become International Alliance Services, Inc.