To be honest, I generally just give them the flick if the OBV looks bad, never really give it much more thought than that. It is usually a sign of distribution when the SP rises and the OBV falls, i.e. larger volume sells than buys. Yes, generally with the small caps it fluctuates in tandem with the SP, the main things I look for is divergence as in your example above. One that I have in a watch list is AV1, the SP is making lower highs, but it is in a consolidation pattern, the OBV during this pattern indicates a good accumulation period. I never trade just off this, but use it more as guide to the underlying momentum.
