The risk the U.K. would vote to exit the European Union, an event dubbed the "Brexit," was one of the biggest risks to the global economy, Lloyd's of London CEO Inga Beale told CNBC.
She said the Lloyd's City Risk Index, which analyzed the potential economic impact of risks to the world's major cities, put the Brexit in the top three, noting that a market shock or crash was the top risk to global gross domestic product.
A version of the City Risk index for 2015-2025, created in partnership with the University of Cambridge, put a human pandemic as the second-biggest risk to key global economies. Beale noted that the index was being updated for this year.
The Brexit referendum will be held on June 23, and while betting spreads have suggested a landslide win for the remain camp, opinion polls indicated a closer call.
A poll published Friday by the Independent newspaper showed that 55 percent of respondents believed Britain should leave the EU, versus 45 percent who favored staying. The publication said it marked the largest portion of respondents who favored exiting since research firm ORB began polling the issue for it last year.
The pound has tumbled over the past few market sessions in response to the leave-leaning polls, dropping from around $1.45 last week to around $1.4190 at 10:26 a.m. SIN/HK.
Lloyd's operates one of the world's oldest insurance markets, in which a number of "syndicates" collectively underwrite global risks.