The criteria was simple. A gap up over the upper Bollinger Band would signal a short entry. The trade would be exited near the close of the day. Looking back to 1998 in the SPY I was able to identify 79 such instances. There were 43 (54%) winners and 36 losers. The average winner made 0.56% and the average loser lost 0.50%. The profit factor was a modest 1.34.
I then broke it down by instances above and below the 200-day moving average. Above the 200-day moving average there have been 62 instances of a gap up above the Bollinger Band. Shorting these and covering on the close resulted in 53% winners. Winners outsized losers by 0.57% to 0.38%. The profit factor was a decent 1.7.
The trouble occurred with this less than “Outstanding” Gap Band strategy when it was attempted below the 200-day moving average. There were 17 instances. Ten winners, but the average loss was 1.0% vs. an average gain of 0.5%. Overall a losing strategy below the 200ma.
As with previous gap studies, it appears gaps up in long-term downtrends are dangerous to try and short. While it would've worked out on Friday, you always need to be wary of a short-covering rally or trend day up.
Initial results of buying a gap down below the lower Bollinger Band appear better. I will look at them in more detail at a later time.