Grahame Gibson, the Chief Operating Officer and Regional head of G4S's Americas division, has sold 100,000 shares in the international security solutions supplier.Gibson sold the shares for 280p per share on June 19th, making a total of £280,000 on the sale. The company was unavailable to comment on the reason for the transaction.He has been a long-running executive in the security industry for the last three decades, having joined Group 4 as Finance Director back in 1983. Group 4 was a UK security firm established in 1968, which merged with Nordic group Falck in 2000 to form Group 4 Falck. Following its merger with Scandinavian group Securicor in 2004, Group 4 Securicor was formed and later renamed G4S in 2007.G4S, the official provider of security and cash services to the London 2012 Olympic and Paralympic Games, announced in May that revenues had risen 7.5% at constant exchange rates in the first quarter of 2012 with the Olympics contract helping to strengthen organic growth."Based on recent contract awards, outsourcing trends and the group's bid pipeline, the organic growth rate is expected to continue to improve during 2012," the company said at the time.Top Director BuysNorth Atlantic Smaller Companies Inv Trust (NAS) Director name: Mr Christopher H B MillsAmount purchased: 5,000 @ 1,032.00p Value: £51,600Greggs (GRG) Director name: Mr Kennedy McMeikanAmount purchased: 7,304 @ 497.00p Value: £36,301Top Director SellsG4S (GFS) Director name: Mr Grahame GibsonAmount sold: 100,000 @ 280.00p Value: £280,000Raven Russia Ltd (RUS) Director name: Mr Mark SinclairAmount sold: 428,000 @ 57.73p Value: £247,084Cranswick (CWK) Director name: Mr Martin T P DaveyAmount sold: 30,225 @ 800.00p Value: £241,800Fidessa Group (FDSA) Director name: Mr John HamerAmount sold: 700 @ 1,521.00p Value: £10,647BC