In finance, an arbitrager is someone who buys currencies, securities, or commodities on one country's market in order to make money by immediately selling them at a profit on another country's market.
[business]
arbitrager in British English
(ˈɑːbɪˌtrɑːʒə) or arbitrageur (ˌɑːbɪtræˈʒɜː)
noun
finance
someone who purchases currencies, securities, or commodities in one market for immediate resale in others in order to profit from unequal prices
This will cause arbitragers to sell British securities, lowering their price.