When Dan Vahdat set out to build a health care startup, the U.K. was an ideal launchpad. That was 2011 and the nation’s deep network of medical research centers and vast National Health Service patient data sets helped him expand the software platform, Huma Therapeutics, into a $1 billion company. For the next billion dollars he is looking elsewhere.

Huma, which helps doctors monitor and analyze patient data, cuts across several sectors that the U.K. government vowed to prioritize after leaving the European Union three years ago. But instead of creating opportunities, Brexit and the political chaos that came with it have fostered an environment that businesses say is increasingly difficult to work with.

Vahdat’s options include moving investment to Germany or France, where French President Emmanuel Macron’s team has reached out to him every few months to discuss business opportunities. The Huma founder is eyeing an eventual listing in New York, with its deeper pools of capital.