[codesci]

Available volume? Forex is the most liquid market in the world.

[foobar2020]

Yes. But if your arbitrage pattern is only 3 pips profitable, and you are exchanging millions at once, you might expect that the amount of available orders matching your path may actually matter.

[murbard2]

1) There's still finite volume at a given price, and the arbitrages, when they do happen, typically involve small volumes.

2) There is more to arbitrage than Forex markets