Generally by watching this chart <A HREF="http://tal.marketgauge.com/dvmgPro/charts/COEXVOL.HTM" target="_blank">http://tal.marketgauge.com/dvmgPro/charts/COEXVOL.HTM</A> Here's another, though unclear <A HREF="http://investmenttools.com/equities/oex_put_call_ratio.htm" target="_blank">http://investmenttools.com/equities/oex_put_call_ratio.htm</A> And it can be calculated manually by dividing puts by the calls currently 1.92 @ 2:30. <A HREF="http://www.cboe.com/data/IntraDayVol.aspx" target="_blank">http://www.cboe.com/data/IntraDayVol.aspx</A> Of course you use the S&P 100 data.