Blackstone has postponed plans to float Merlin Entertainments, the operator of Madame Tussauds and Legoland, just 24 hours after shelving plans for a £1.2bn listing of Travelport.

The two IPOs would have been the largest since before the financial crisis, and their withdrawal will come as a heavy blow to the market.

The Merlin IPO was at an earlier stage than Travelport’s and a flotation is likely to proceed at some stage because the theme park operator’s management wants an IPO rather than a trade sale.

It is understood that Blackstone postponed the IPO because of severe volatility in the markets over the past three weeks, and that it could yet take place before the general election.

The debt crisis of eurozone countries, such as Greece and Spain, and American plans for a bank levy have caused the so-called fear index – the Vix – to increase to a three-month high.

Travelport’s float was pulled due to weak investor appetite, however Merlin was expected to receive a good reaction from institutions because of its solid business model, growth prospects and highly-regarded management. Last week it announced the acquisition of a theme park in Florida.

Merlin had been expected to confirm its intention to float on Monday, with the shares likely to be listed just before Easter.

Goldman Sachs and Citigroup were due to lead the IPO as joint global co-ordinators, with Deutsche Bank and Nomura acting as additional bookrunners. Blackstone, which owns slightly more than 50 per cent, was expected to sell down its holding in the IPO, with the level of its disposal depending on the price achieved.