as at 31 December(Quarterly Update Report as at 31 December 2014. The information contained in this announcement is restricted and is not for release, ... Alexander Demidov)
at year-end(год: Despite shifts in early and serious delinquency rates from year-end 2015 to year-end 2016, the total delinquency ratio remained stable at year-end 2016 – by Maine Bureau of Financial Institutions Tamerlane)
as at("As at" suggest that a calculation was performed at one particular point in time and the results were applicable then, but may have already or will possibly change in the future. Whereas, "as of" suggests that the calaculation was performed and from that date up until now the results remain the same. OGC)