Andrew
If you want to do a momentum based strategy the best I can recommend is to use the DollarVolumeUniverse I linked too above. Grab the price history for the securities price_histories = history(20, "1d", "price") and to get the momentum which we will define as: the latest price / the oldest price, you can iterate through your securities:
for security price_histories:
momentum = price_histories[security][-1] / price_histories[security][0]
There are other ways to do this like applying the division to the whole dataframe, but this is a really good way to get started and see what is actually happening in a more "normal" context. Once you calculate the momentum you can store it or use it immediately.
I hope that helps. Check out these other momentum strategies (some are harder to follow than others):
Momentum Quick and dirty
Cross sectional momentum <=== more advanced
Good luck
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