Actually, I haven't been using SKF.
I've been using UYG for up market and QID for down market.
I see you are interested in NDX gaps. It's interesting to note that SPX hasn't gapped at all for almost four months. It would be interesting to know if NDX would have gapped on Friday if GOOG, AAPL, RIMM, and short covering were taken out of the data. Only eleven stocks own 50% of NDX.
SPX and COMPQ are sitting at overhead resistance, and the probability of another Fed rate cut is dropping significantly. Financials, DJUSFN, couldn't hold at resistance on Friday.
Market Data 
Markets 
AI
