Security firm G4S has admitted it is fighting to repair its battered reputation, as it wrote off £50 million in losses on its bungled London 2012 contract.
It fulfilled 83% of contracted shifts at the Games, failing to provide all of the 10,400 contracted guards and forcing the Government to step in with military personnel, the group confirmed.
G4S, which has already ruled itself out of bidding for the Rio 2016 Olympics security contracts, said it is confident that the Paralympic Games, starting on Wednesday, will be fully staffed with a security workforce.
It is conducting an internal review after the Olympics debacle which saw troops plug a shortfall left by G4S just weeks before the event started.
Chief executive Nick Buckles said: "We were deeply disappointed that we had significant issues with the London 2012 Olympics contract and are very grateful to the military and the police for their support in helping us to deliver a safe and secure Games. Clearly it is a big setback and we need to rebuild the brand over the coming months and years."
The £50 million expected loss on the Games contract is at the upper end of what the firm initial expected. G4S said the final amount could be higher because of contract penalties and with the actual cost to the Government of providing military personnel yet to be calculated.
The Government put another 4,700 personnel on standby, on top of 13,500 initially committed, after G4S admitted its shortfall in July. G4S said not all of these were used as it provided nearly 8,000 staff for the Games.
The £50 million hit contributed to a drop in half-year, pre-tax profits to £61 million from £151 million a year earlier, although underlying profits were the same as last year at £236 million as sales increased 5.8% to £3.9 billion.
Mr Buckles said no G4S contracts were lost after the bungled Olympics contract and insisted that the group will continue to play a major role in the public sector, with an overall £3.8 billion-a-year contract pipeline.
But he confirmed that the resources G4S put into sorting out the Games debacle meant it withdrew from bidding for a Department for Work and Pensions contract worth £20 million a year.