(ShareCast News) - Northbridge Industrial Services board members have been buying stock to bolster the company's share price.Chief executive Eric Hook and chairman Peter Harris both purchased 150,000 and 100,000 shares in the company on Monday at 70p per share.Western Selection, of which non-executive director David Marshall is the chairman, also purchased 600,000 shares in the company.It followed a dramatic fall in the share price from October 21, for which Northbridge released a statement saying they are not aware of any specific reason for the share price movement.The purchase appears to have given the market confidence with shares sitting at 94.20 at 1539 GMT, up 23.2p (32.68%).Top Director BuysNorthbridge Industrial Services (NBI)Director name: Mr Eric W HookAmount purchased: 150,000 @ 70.00pValue: £105,000 Northbridge Industrial Services (NBI)Director name: Mr Peter R HarrisAmount purchased: 100,000 @ 70.00pValue: £70,000 Development Securities (DSC)Director name: Mr Richard UptonAmount purchased: 6,250 @ 240.00pValue: £15,000 Top Director SellsJardine Matheson Holdings Ltd (Singapore Reg) (JAR)Director name: Mr E P K WeatherallAmount sold: 14,000 @ $53.00Value: $741,940 Boxhill Technologies (BOX)Director name: Mr Lord RazzallAmount sold: 14,000,000 @ 0.32pValue: £44,800