Is there any effect in which day of the week you buy or sell? (WeekDay = )

The fundamental data is available and up to date even on a weekday. If you run a ranking system today it'll reflect the latest fundamentals.

The ranking in backtests is performed only on the weekends. Other than ranking, backtests use daily values for prices and weekly values for fundamentals. Fundamentals are weekly historically and daily on the current date.

1 Like