YTD Performance start date Question

CFA Level III Portfolio Management
#1

When doing performance attribution year to date, the correct start date should be the close of last trading day in December, to account for the entire investment performance of the first trading day in January.

I am having trouble finding an “official” source for this besides common sense? Can anyone point me to something conclusive in the cirriculum?

Thank you -

#2

They talk about that in GIPS, that the end of the year or reporting period is either Dec. 31 or the last business day of the year. I read Schweser for GIPS but I’m sure CFA reading 34 has it in there.

#3

thank you!