Quote from late apex:
You are thinking of one particular textbook example of arbitrage (3 securities), assuming a perfect, idealized, ivory tower market. In the real world, even 2 securities is not necessary. Scalping 1 currency pair with accounts at 2 dealers, or even 2 accounts at the same dealer, also falls under arb.
<b>Many thanks for replying</b>,
I will ask them to confirm that.
I wonder what makes a broker decide that it was arb?