EasyJet
Monarch has gone into administration after failing to secure its financial future over the weekend. It is the largest ever UK airline collapse.
All future flights have been immediately cancelled, affecting an estimated 300,000 bookings.
Shares in other airlines are substantially higher as traders sense an opportunity for other carriers to grow market share on the back of Monarch's collapse.
Neil Wilson, a senior market analyst with ETX Capital, says in an emailed statement: "The failure of Monarch is good news for rivals. Shares in Ryanair and EasyJet both rose about 3% in early trading as the market reacted to the news of the demise of Monarch after 50 years in business. IAG and Lufthansa were both about 2% higher."
Three of the four airlines which are larger than Monarch - British Airways, easyJet, and Flybe - are publicly traded and have seen shares jump. The fourth, Jet2, is in private ownership.
Europe's largest airline by passenger traffic, Ryanair, has also seen big gains on Monday morning. Ryanair is headquartered in Ireland, but listed on the London Stock Exchange.
Here's how International Consolidated Airlines Group - the parent of British Airways - looks as of around 9.20 a.m. BST (4.20 a.m. ET):
Investing.com
And here's how easyJet, Flybe, and Ryanair are trading on Monday morning:
Investing.com
Investing.com
Investing.com