I was one of the first people to do inter exchange arbitrage. It ins't necessary extreme speed, in fact for me it took more than a month to settle. I would fi

I was one of the first people to do inter exchange arbitrage. It ins't necessary extreme speed, in fact for me it took more than a month to settle. I would first wait my program notify me there was a 20% or more profit opportunity (due to the slowness and risk). Then I would buy btc with credit card on some usd exchange (usually mtgox, not always), then I would sell btc for brl on a Brazillian exchange. I would pay the credit card with my brl when the bill came... this could take more than a month, and I would pay lots of taxes, but I would still turn a profit. The reason I stopped doing arbitrage was that to me was too time consuming, because every month the payment methods would change (for example someone one month accepted paypal, then only cc directly, then only paypal again, then some paypal competitor where I had to register...)