http://bigcharts.marketwatch.com/int... the 10 day chart on bigcharts gives and idea of the level of trading, an can be set to 1 min ticks with positive/negative volume.

The trouble is that trading 'can' go through on the same price - ie bid and ask is equal, which might be market makers, but on the other hand depending on the stock, if there's low volume trading, just business as normal. Ive noticed for ECU when large volume spikes occur and the trade range is given as the same bid and ask, it often painted as negative volume, even when there is very little subsequent impact on trading.

You can only really get an accurate picture with level two, it seems today had more to do with futures trading, not sure what of, but ECU seems to be back up anyway