Well, maybe. But try this on Yahoo! with 11,000 stocks at once :D
# Buy if a previous value was below the low Bollinger band and is now above
SET Bottom = BBB(CLOSE, 20, 2, EXPONENTIAL)
SET Top = BBT(CLOSE, 20, 2, EXPONENTIAL)
FIND STOCKS WHERE (((REF(CLOSE, 1) < REF(Bottom, 1)) AND...