The U.K. will hold a referendum on June 23, in which the electorate will vote on whether the country should remain in the EU or go its own way — the so-called Brexit.
"The CHF would likely rally on Brexit, given the political and European-centric nature of the crisis ," HSBC currency strategists, David Bloom, Daragh Maher and Mark McDonald, said in a report.
"The Swiss National Bank may intervene, but we believe it would only, at best, be able to slow the move rather than reverse it.
"However, were Brexit rejected, we would not expect maintenance of the status quo to provoke much CHF weakness. There is little evidence that CHF has priced in much Brexit risk, which means there is little risk premium to disappear. This asymmetry makes the CHF the best choice as a hedge."
Going long is when a currency or other security is bought in the expectation that it will rise in value and the investor will profit. A hedge is an investment taken to offset the risk of adverse movements in asset prices. (CNBC Explains.)