Yes, ARBITRAGE is a Scrabble word!

Letter values in Scrabble US: A 1, R 1, B 3, I 1, T 1, R 1, A 1, G 2, E 1.

Is it a valid word?

ARBITRAGE is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a kind of hedged investment meant to capture slight differences in price; when there is a difference in the price of something on two different markets the arbitrageur simultaneously buys at the lower price and sells at the higher price