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On 12/15/2018, the prior quarter end is 9/30/2018.
The dynamic quarterly return as of 9/30/2018 needs a starting period NAV from 6/30/2018 (the end of day NAV).
The dynamic mutual fund field internally looks back an extra day when deriving begin date so when the date is 12/15/2018 the date rule needs to return the following values:
Begin Date = 7/1/2018 (dynamic process converts it to 6/30/1418)
End Date = 9/30/2018 (end date of the prior quarters return)
This is shown in the following figure.
The Start Date is set to calculate the end date by going back two quarters.
The End Date is set to calculate the end date by going back one quarter with an additional offset by one day.
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