LONDON (AP) — A survey shows that companies' initial public offerings of shares fell by a fifth in the first half of 2018 due to geopolitical tensions like Brexit and the threat of trade wars.

In a report released Thursday, law firm Baker McKenzie cites the lack of progress in Britain's exit from the European Union and U.S. President Donald Trump's decision to impose tariffs on several countries.

IPOs held in the countries where companies are based fell by 18 percent in volume from a year earlier. Cross-border IPOs held up better, increasing by 15 percent.

Despite concerns over protectionism, over half of Chinese issuers listing abroad in the first half of the year chose U.S. exchanges over Hong Kong.