What's going on?

A bidding war for G4S � the world�s biggest security firm � came to an end on Monday, and its shares dropped by their most in a year. Didn�t see that coming�

What does this mean?

With a rise in the fear of terror attacks has come a rise in the global security market, and Allied Universal and GardaWorld � both private companies � are battling to run the show. So what better way to do that than by acquiring UK-listed G4S, which has been plagued by multiple crises � from lost prison contracts to alleged human rights abuses � over the last few years.

GardaWorld saw its moment to strike when last year�s market turbulence took its toll on G4S�s share price, and it made a hostile bid to take over the business. But Allied took a more softly softly approach, wooing G4S with acquisition talks until � after months of back and forth � it finally won the face-off on Monday.

Why should I care?

For you personally: Try not to jump the gun on mergers and acquisitions.�

G4S�s shares had risen 80% since the start of the stand-off, and investors might�ve been hoping Allied Universal and GardaWorld�s rivalry would keep driving the price up. But when GardaWorld refused to raise its latest bid, investors reversed course and sent its shares down 10%. So if you�re eyeing up takeover candidates� stocks, it�s worth remembering that the process can lead to big price moves � and nothing�s a done-deal till the deal is actually done.

The bigger picture: Regulators could poop on the party too.�

There�s one other big risk to the takeover process: regulators can block an acquisition if they think it might hurt consumer choice or disturb a key national industry. Case in point: Canadian convenience store chain Couche-Tard was told last month it wasn�t allowed to take over French food retailer Carrefour, after the latter�s government put its foot down and said �Mais non!�