Demand to borrow stock from Air-France-KLM has increased by just over six per cent, with 4.9 per cent of the stock out on loan, a record high, in spite of its US partner Delta taking a stake in Virgin Atlantic, according to the data from Markit.
Shares in Virgin Australia, which is also part-owned by Sir Richard Branson and listed in Australia, have also soared in demand.
The total shares out on loan have jumped 142.4 per cent over the month and now stands at 4.2 per cent of share lent out.
Hedge fund traditionally borrow shares to short the stock and make money if the share price falls.
The top three shorted stocks remained US airlines, Jetblue Airways, US Airways Group and United Continental.
The only London listed airline on the top 15 list is EasyJet.
Shares out on loan in the business have increased 27.5 per cent over the month, with 2.6 per cent of shares now out on loan.