The Press Association understands the group has secured the majority of the ill-fated carrier’s slots at Britain’s second-busiest airport after tabling a significant bid that trumped rival airlines.
It has been reported Monarch’s slots at Gatwick and Luton are worth in the region of €70 million, with the most valuable at the West Sussex airport.
Shares in IAG were up more than one percent in afternoon trading on the London Stock Exchange while easyJet was two percent ahead.
The move comes after IAG chief executive, Willie Walsh, said last month thatthe firm was mulling over a swoop for the slots to help boost its long-haul budget airline level, which it launched in June.
IAG, which also owns Vueling and Aer Lingus, is stepping up its position in the low-cost, long-haul market as it looks to fend off fierce competition from the likes of Norwegian Air Shuttle.
A string of airlines had been linked with the runway slots since Monarch’s collapse in September, with easyJet, Norwegian, Wizz Air and Jet2 all understood to have made enquiries.
Administrators KPMG won a court battle to sell the “valuable” slots on Wednesday after overturning a High Court ruling earlier this month.
The collapse of Monarch in October, which was owned by private equity firm Greybull Capital, led to 1,858 workers being made redundant and the flights and holidays of about 860,000 people being cancelled.
Alongside Gatwick, Monarch’s runway slots at Luton Airport are also being auctioned off.