The Fast Stochastic is an oscillator that is displayed as two lines. The first line, %K, is the main stochastic calculation. The second, %D, is a moving average of %K. The Stochastic compares the closing price of a security relative to its price range over a selected period of time.
This is a companion discussion topic for the original entry at https://www.optuma.com/kb/optuma/tools/price/fast-stochastic