Cancer biotech firm Immunocore is looking to list on the Nasdaq rather than London as it aims to raise up to $100m.
The Oxford-based company delivers biological therapies for people suffering with cancer and other serious diseases.
Last week Immuncore secured $75m in fresh funding after a Series C round, bringing its total raised through private placements to $873.2m.
The funding followed a positive Phase 3 trial for its lead programme tebentafusp, which helps patients with a form of eye cancer.
It is a blow to the City which is gearing up for a bumper year of tech floats, including Darktrace and Transferwise. The government launched a review into rules surrounding public lists to avoid British companies looking across the Atlantic to list.
But at the end of last year electric vehicle startup Arrival announced plans it had agreed to merge with the Nasdaq-listed blank-check company CIIG Merger Corporation.
There has been somewhat of a frenzy for special acquisition companies (Spacs) which raise money on the stock market to buy an operating company.
It had previously been a niche strategy for small investment firms but their popularity has grown as companies back away from traditional listings.