The Bullish Engulfing Pattern candlestick formation occurs when a large white body engulfs a previous small black body in a downtrend. To quantify, the white body should be at least as big as the average body size of the last 5 days, while the small black body only needs to be smaller than the large white body. We define a downtrend here as lower prices for 3 days, up to the black body. However, the black body does not have to have a lower low than the white body. The black body simply has to be engulfed by the white body.