A Lloyd’s of London insurer has dealt a fresh blow to the City by snubbing the London Stock Exchange in favour of New York for its planned IPO, piling fresh pressure on the capital’s bourse after it shrank at the fastest pace on record last year.

Aspen Insurance, an underwriting firm which operates out of the Square Mile’s historic insurance market, filed papers last month with US regulators for a potential £3bn float on the New York Stock Exchange, expected to take place in the coming months.

The insurer had previously mooted a New York listing but shelved the plans last year while volatility was still roiling the IPO market. 

However, the revival of the plans will be seen as a blow to London after the government and bosses at the London Stock Exchange and City regulator have mounted a push to revive London’s flagging IPO pipeline.

In July, the Financial Conduct Authority pushed through what it called the biggest shake-up of listing rules in 30 years in a bid to tempt more companies onto the public markets.

However, London’s markets shrank at their fastest pace on record last year after a deluge of companies either delisting or agreeing to take-private deals by trade buyers and private equity firms.

Some £52bn worth of companies were taken over last year while just 18 new firms floated across the London Stock Exchange’s main market and junior AIM exchange.

Some of the UK’s biggest listed firms also announced they would ditch their main London listings in favour of foreign exchanges, including takeaway giant Just Eat, Paddy Power owner Flutter, travel group Tui, and equipment rental firm Ashtead.

The London Stock Exchange (LSE) saw 88 companies delist or transfer their primary listing from the main market – the most since 2009, according to data from auditing giant EY.