B.I.N.G.O. rather than plot VWAP +/- stdev(VWAP) create a variable called diff Let diff = VWAP - P The variable gets updated at each step as VWAP and Price get updated. then calculate stdev(diff) add +/- 3 of these stdev pts to each VWAP pt. in your data series. Overlay that with the price series. This also gets updated at each step. Buy me a beer one of these days. Cheers.