Hello @laurens,

Do you mean the dates that you see on tab "Universe" of template (Excel -> Thomson Reuters tab --> templates button (left top) --> CUSTOM PRICE INDEX).?

=TR($C$6:$C$558,"TR.CompanyName;TR.PriceClose.date;TR.HeadquartersCountry","CH=Fd NULL=BLANK",D5)

These are the same TR.PriceClose.date, i.e. date of TR.PriceClose, not when the index was calculated.

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Perhaps this will be helpful:

If you would like to calculate GRWAVG by means of python pandas rather then EDAPI, you can do something like this:

groupby-weighted-average-and-sum-in-pandas-dataframe

i.e.

df7,err = ek.get_data( instruments = ["REL.AS","ABNd.AS",
       "ADYEN.AS","AEGN.AS","AD.AS","AKZO.AS","MT.AS","ASMI.AS",
       "ASML.AS","ASRNL.AS","DSMN.AS","GLPG.AS","HEIN.AS","IMCD.AS",
       "INGA.AS","TKWY.AS","KPN.AS","NN.AS","PHG.AS","PRX.AS","RAND.AS",
       "RDSa.AS","URW.AS","UNA.AS","WLSNc.AS"]    , 
       fields = ["TR.CompanyMarketCap,TR.PriceClose, TR.PriceClose.Date"],
       parameters = { 
                'universe': 'univ', 'Curn' : 'EUR', 'Sdate':'2020-09-01', 'Edate' :'2020-09-30', 'frq':'WD'}
                          )
df7

and

def weightedaverage(df,data_col,weight_col,by_col):
    df['_data_times_weight'] = df[data_col]*df[weight_col]
    df['_weight_where_notnull'] = df[weight_col]*pd.notnull(df[data_col])
    g = df.groupby(by_col)
    result = g['_data_times_weight'].sum() / g['_weight_where_notnull'].sum()
    del df['_data_times_weight'], df['_weight_where_notnull']
    return result
df = weightedaverage(df7,'Price Close','Company Market Cap','Instrument')
df

Hope this helps

Hello @laurens,

I suspect the issue may not be with dates, but with GRWAVG function.

This request works for me

ek.get_data( 
            instruments = ["REL.AS","ABNd.AS",
        "ADYEN.AS","AEGN.AS","AD.AS","AKZO.AS","MT.AS","ASMI.AS",
        "ASML.AS","ASRNL.AS","DSMN.AS","GLPG.AS","HEIN.AS","IMCD.AS",
        "INGA.AS","TKWY.AS","KPN.AS","NN.AS","PHG.AS","PRX.AS","RAND.AS",
        "RDSa.AS","URW.AS","UNA.AS","WLSNc.AS"]    , 
            fields = ["TR.CompanyMarketCap,TR.PriceClose, TR.PriceClose.Date"],
            parameters = { 
                'universe': 'univ', 'Curn' : 'EUR', 'Sdate':'2020-09-01', 'Edate' :'2020-09-30', 'frq':'WD'}
                          )

returns dates:

Does this help?

Dear @zoya.farberov,

Thanks a lot for your fast response. The formula that I am using is similar to the Refinitiv excel template (Excel -> Thomson Reuters tab --> templates button (left top) --> CUSTOM PRICE INDEX). In this excel sheet also the date is displayed at which the index is calculated. I was therefore hoping I could use this formula to get indexvalue and indexdate

In your proposed change I now know the value of the induvidual stocks at the different dates but I still don't know the exact date at which an index value is calculated. Especially when data is missing e.g. not returned it is quite important to be able to check dates before you start calculating stuff on index values like e.g. returns.