arbitrageur
noun [ C ]
FINANCE (also arbitrager) uk/ˌɑːbɪtrɑːˈʒɜːr/ us/ˈɑːrbɪtrɑːʒɚ/ (also arb)someone who buys something, such as shares or currency, in one place and sells them in another where they can get a higher price at the same time:
Traders said that overseas arbitrageurs were buying the stock in London in the hope of selling it at a profit in Johannesburg.