Shares in BAE Systems have risen over 6% in value after the UK government agreed to supply Saudi Arabia with the new Eurofighter.
The Eurofighter has taken more than 20 years to design and build
This is the first contract for the jet outside Europe and will safeguard thousands of UK jobs.
The Eurofighter has been developed by a consortium of firms in the UK, Germany, Spain and Italy.
It is competing for market share against two rival jets, the US Joint Strike Fighter and the French Rafale.
The Royal Saudi Armed Forces are on a mission to modernise, which will see the Eurofighter Typhoon replace the Tornado in the Royal Saudi Air Force.
BAE has provided Tornado planes to Saudi Arabia since 1985.
Both BAE and the Ministry of Defence were keeping mum about the precise number of Eurofighters that would be sold to Saudi Arabia but the deal is rumoured to be worth more than £6bn ($10.6bn).
"The specific details of these arrangements are governed by the existing confidentiality agreement," the British embassy in Riyadh said.
Notably, the Saudi agreement is only the second export deal for Eurofighter - Austria previously bought 18 of the aircraft.
The countries behind the Eurofighter have ordered 620 of them.
The Eurofighter has its UK base at Warton, Lancashire, where BAE Systems employs 9,000 people in its aircraft division. These jobs will be safeguarded by the deal over the next 10 years, said UK defence secretary John Reid.
Shares in BAE Systems hit a three-year high on Wednesday, up 22.25 pence to 370p.