Securicor is attempting to forge a nil-premium merger with Denmark's Group 4 Falck, the companies said yesterday.
The enlarged security services business would be dual listed, in London and Copenhagen, and the new company would be structured so that it would be included in UK stock market indices. "The merger would be effected by a newly formed UK plc," the companies said.
Group 4 Falck is the world's number two player in the industry, behind Sweden's Securitas. It had previously been thought that any deal with Group 4 would have involved a takeover of Securicor rather than a merger.
In order to bring down its size, Group 4 will spin off its non-security operations - its Safety and Rescue and Global Solutions businesses.
It is understood that the board of the merged company would be picked from the existing top management of both companies, including a position for Securicor's chief executive, Nick Buckles.
It is still not clear whether it would actually be a 50-50 merger. The businesses to be divested by Group 4 make up about a fifth of its earnings.
Before share price movement yesterday, Securicor was worth £600m, compared with Group 4's £1.1bn stock market value. The combined group could be sizeable enough to get into the FTSE 100 index.