For the benefit of the conversation, and posted without taking a position, here is the OED's definition of arbitrage:

Comm. The traffic in Bills of Exchange drawn on sundry places, and bought or sold in sight of the daily quotations of rates in the several markets, each operation being based in theory on the calculation known as ARBITRATION of Exchange, q.v. Also, the similar traffic in Stocks, so as to take advantage of the difference of price at which the same stock may be quoted at the same time in the exchange markets of distant places. [In this sense adopted from mod.F., and usually pronounced ({sm}{fata}{lm}bitr{fata}{lm}{zh}).]

Here is the OED's definition of Arbitration of Exchange:

Arbitration of Exchange (cf. F. arbitrage in same sense): The determination of the rate of exchange to be obtained between two countries or currencies, when the operation is conducted through a third or several intermediate ones, in order to ascertain the most advantageous method of drawing or remitting bills.

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