The forex market is “over-the-counter” with independent brokers and traders all over the world creating a non-centralized marketplace. While some brokers publish the volume produced by their client orders, it does not compare to the volume or open interest data available from a centralized exchange, such as a futures exchange.
Statistics are available for all futures contracts traded, and open interest can help gauge sentiment. Open interest, simply defined, is the number of contracts that have not been settled and remain open positions.
If, say, the AUD/USD currency pair is trending higher, looking to open interest in Australian dollars futures provides additional insight into the pair. Increasing open interest as the price moves up indicates the trend is likely to continue. Leveling off or declining open interest signals the uptrend could be nearing an end.