As I think about this more, here's what I come up with. Money flow is defined by WSJ as dollar value of uptick trades minus dollar value of downtick trades. So, a negative money flow on a rising stock simply means that there is more market selling going on, and the bids are holding well. Similar to a delta divergence which I often post about. This may in fact be bullish, and bearish for the opposite scenario. This calculation does not seem to take into account market positions as does open interest; thus I'm not sure how useful it is, versus something we have real time like a delta. I will do some comparison of delta to what I see on the WSJ page in the next day or two and see if I see correlations.