“Though we have seen some progress in the Brexit negotiations, GBP still probably remains a currency that some investors have stayed underweight and could surprise as an outperformer,” Tuchman, from Citi, told CNBC.

At the same time, the Bank of England, which raised rates for the first time in more than a decade in November, is set to gradually tighten its policy, which could support the currency further. Markets have priced a rate hike next year, but some analysts believe there could be two hikes.

“As we enter 2018, there is less of a consensus view on the USD, although most people believe that broad USD weakness can persist,” Tuchman said. “The political risks in Europe and the U.K. seem much reduced, the BOE has raised rates already once and while policy rates remain accommodative in the Eurozone and in Japan, more talk these days is about when the European Central Bank and the Bank of Japan will ultimately end their quantitative easing programs and in Europe’s case, raise rates.”

Disclosure: NBCUniversal, parent of CNBC, is a minority investor in Kensho.