LONDON -- The shares of G4S (GFS) have dropped a modest 0.2% after chief executive Nick Buckles said he would leave the group at the end of the month.

Buckles will be replaced by Ashley Almanza, who was appointed chief financial officer of the security firm only three weeks ago. Stuart Curl, the company's regional financial officer for the U.K., Ireland, and Africa, has been appointed acting CFO.

John Connolly, the chairman of G4S, said:

Nick Buckles made a massive contribution to the group over a 28-year career. As CEO he led G4S in the creation of significant shareholder value following the merger of Securicor and Group 4 Falck -- building the world's leading security company. On behalf of the board and everyone at G4S, I thank Nick and wish him the very best of luck for the future.

Buckles' departure from the FTSE 100 member follows a series of mishaps.

During 2011, Buckles launched a £5.2 billion bid for Danish outsourcer ISS -- only to withdraw the approach two weeks later after shareholders raised concerns about the deal's scale and complexity.

Last year, G4S hit the headlines for failing to recruit enough staff to fulfil its security obligations at the Olympics. The Games organizers had to draft in the army, and the company lost £88 million on the contract.

Then earlier this month, G4S admitted that first-quarter margins had been trimmed by 0.6% and acknowledged that further pressure on profit would continue throughout the year. The shares slumped 12% on the day.

With a market cap of £3.5 billion, G4S trades at about 12 times expected earnings and offers a prospective dividend yield of 3.9%. Of course, whether that valuation, the resignation of Buckles, and the wider prospects for the security industry all combine to make G4S a buy remains your decision.

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