In the statistics of time series, and in particular the analysis of financial time series for stock trading purposes, a moving-average crossover occurs when, on plotting two moving averages each based on different degrees of smoothing, the traces of these moving averages cross. The particular case where simple equally-weighted moving-averges are used in sometimes called a simple moving-average (SMA) crossover. Such a crossover can be used to signal a change in trend and can be used to trigger a trade in a Black Box trading system.