Today’s Chart of the Day was shared on Twitter by Todd Gordon (@toddgordontrade). It’s a chart of the NYSE Tick Index ($TICK) with a 10-period moving average in blue. In purple is the S&P 500. The Tick Index is a short-term indicator often used by day traders. It measures the number of stocks in the NYSE on an uptick, minus the number of stocks on a downtick. In another tweet, Todd adds: “Sub -600 readings and lower indicate institutional sell programs. If those damn machines are hitting bids the selling abates.” You can see that the tick index made three higher-lows while the S&P 500 made three lower-lows. Sure enough, this divergence was followed by a small relief rally in the afternoon.