Originally announced in July as a stock transaction, the deal had been considered doubtful for some time because of volatility in Republic's stock value. Meanwhile, Western Resources, a US utilities company that holds 24.3 per cent of ADT, had also made plain its opposition to the merger.
Its collapse will bring embarrassment to Wayne Huizenga, the chairman of Republic, who is famed in the US for his aggression in building businesses. Mr Huizenga is the mogul who forged the Blockbuster video retail empire, which he finally sold for $8.4bn.
Since assuming control of Republic last year, at the time a sleepy waste haulage business, Mr Huizenga has engineered more than 30 acquisitions, turning the company into a combine with security, waste haulage and used- car interests. The absorption of ADT, already the largest security firm in the US, would have transformed Republic into the unassailable leader in the sector.
ADT, chaired by Mr Ashcroft, saw its shares dip on the news in early trading in New York yesterday by $1 to $18.875. Shares in Republic were pushed up slightly.
"The delay in completing the transaction forced both companies to put business expansion plans on hold for too long," Mr Ashcroft said in a statement. "Both companies will now be free to resume their individual business plans."
Analysts will watch Western Resources, which may be interested in taking majority control of ADT.
The merger, which had been scheduled for completion before the end of the year, was probably doomed last summer when shares in Republic tumbled from a high of $29 when the deal was first announced to lows of around $20. Thus, the returns that had been promised to ADT shareholders, including to Western Resources, suddenly seemed deflated.
"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," Mr Huizenga said in a statement of his own.Reuse content