Stochastic MACD (SMACD) is an oscillating momentum indicator, that combine the Stochastic oscillator and MACD (Moving Average Convergence/Divergence). SMACD is based on the difference of two exponential moving averages (EMA) and their relative positions compared to the highest and lowest prices of a certain period (standard 45).
A possible high/low is around 15, so those values have been marked with a dotted line.
SMACD have proven to better show positive/negative divergences compared to the traditional MACD indicator. The indicator itself is very close to the MACD, but differ in the way you can compare the historical values.