If you add up all the BTC volume across all currencies for MtGox its about 780,000BTC over 30 days.. so BTCChina still has a little ways to go to knock them off the top in terms of BTC Volume.
Not to mention BTCChina has zero trade fees at the moment, which makes me very suspicious about their volumes.
You can't just "add up" all the
BTC volume across all currencies for Mt. Gox. That would be double-counting. To understand this, one needs to understand how Mt. Gox works.
You see, Mt. Gox doesn't have a market for each currency. Rather, all currencies share a single trade book. When an order is placed with one currency, it is injected into the trade book and potentially matched with other currencies. Thus, traders in obscure currencies have the benefit of being able to trade with a more mainstream currency.
There are then two types of Mt. Gox transactions: transactions with two of the same currency markets (e.g. USD and USD or EUR and EUR), and transactions between two different currency markets (e.g. USD and EUR). Because the USD market is so much larger, most of the volume for other currency markets has already been counted in the USD currency market.
Thus, adding up the volume across all currencies for Mt. Gox is a gross overestimate. The USD volume is much, much closer to actual volume.
Are you 100% sure of that? because i had order in euro that were not fulfilled completely while an equivalent higher price in $ was hit.
See:
https://support.mtgox.com/entries/20800336-Multi-Currency-TradingQ. Do you keep independent ask/bid tables for different currencies?
A. No, ask/bid tables for different currencies are not independent. All currencies are relative to whichever currency has the highest volume, which is based on said currencies current market price in bitcoin. Every trade is in one pool and in fact, not are not separate currency markets. This allows users the added benefit of trading in "the greater market" -in currencies they understand- while not limiting them to smaller currency markets.
For example, if a buy order for bitcoins is placed in EUR, the order can be executed against another user selling bitcoins in any currency and not necessarily only against another user selling bitcoins in EUR.
