London’s investment appeal is unraveling as Arm heads to the U.S.

London’s investment appeal in a post-Brexit world is rapidly deteriorating.

After a tumultuous year in which it lost the top spot among Europe’s stock markets, London is now grappling with a slate of companies — including SoftBank-owned Arm, the jewel of Britain’s technology industry — ditching local listings in favor of the U.S.. Beyond tech, firms such as CRH PLC, one of Europe’s largest building materials producers, see capital markets across the Atlantic as more attractive.

The trend is ominous for flagging initial public offerings in the U.K. It also sets back efforts to transform what is widely perceived to be a dinosaur equity market that’s overly reliant on old economy sectors such as oil and banks. Coming at a time of stalling economic growth, it could mean more money leaving domestic equity funds after record outflows of $26.3 billion last year.