An indicator that multiply the closing price with the current volume. (close X volume)
This will show the relative interest in the underlying asset regardless of the price change over time. For the case of FXCM, when the price fell from $16 to $1, its volume spiked 16x at the same time given the fact that 16x more shares can now be purchased with the same amount of dollar.
Enjoy! and remember to give a thumbs up.