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Getting Started - Open and close prices question

So I was going through the first tutorials, and on tutorial 1.7 where you schedule your orders , you can open to close your position at a specific time in the market.
My question is, does the price fluctuate a lot at week opening or week closure ? I tried to run some algorithms where I delay the buying of the stocks at the beginning of the week by 30 minutes , and I close 30 minutes ahead of closure. It made 3% less profit than if you buy them directly at opening - over the span of 57 months!! I was expecting a much higher difference honestly. ( I allocated 50% of the portfolio in SPYG and 50% in cash).
Maybe this is too basic but I would like to know your opinion on the price fluctuations at week opening and closing.

Thanks,
-Pascale

1 response

Welcome to Quantopian.

That's the exact kind of question that you can answer in a research notebook easily rather than running a bunch of tedious backtests. You can all of the price history, and then slice it by day/hour/day-of-week, whatever you want, and calculate the mean and median and standard dev or whatever you want of the various time periods.

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