Via the BitPay website…
Effective immediately, BitPay has temporarily stopped using Mt. Gox for determining the exchange rate for our invoices.
The rate calculation that BitPay uses for each invoice is now as follows:
1. Pull the full Level II market depth, on the bid side, from multiple exchanges.
2. Merge the market depths into one Consolidated Level II table.
3. Calculate the blended clearing price for the amount of the invoice, assuming an auto-routing market sell order across all exchanges, with zero commission.
BitPay is committed to offering the fairest possible rate to the buyer, while minimizing our counterparty risk.