CREATE SET [Days Count 4] as 
    {StrToMember("[Sale Date].[Date].[Date].&[" + Format(Now(), "yyyyMMdd") + "]").LAG(1)};  
CREATE MEMBER CURRENTCUBE.[Measures].[Запасы. Текущие остатки, шт]
 AS sum(
        intersect(
            [Days Count 4], 
            [Sale Date].[Date].[Date].MEMBERS
        )
        ,[Measures].[Qty Balance]
    )
,FORMAT_STRING = "#,##;-#,##"
,VISIBLE = 1
,ASSOCIATED_MEASURE_GROUP = 'Inventory';