st: Merge data for two panels in a panel data set

["rado645-bg@yahoo.de" <rado645-bg@yahoo.de>]

Dear all,

I have two firms in a data set that merge at a given point of time. For a specific reason, I need to sum the observations over their balance sheet items in each period of time. Would that be possible in Stata? 


The dataset looks like that:

Firm        Date    Item1    Item2    Item3


Firm1     Date1   Item1    Item2    Item3

Firm2      Date1   Item1     Item2    Item3

Firm3      Date1  Item1    Item2     Item3

...so on.

I would like to merge in each period of time the data for firm 1 and firm 2 so the dataset will look like that: 


The dataset looks like that:

Firm                  Date     Item1  Item2  Item3


Merged_Firms    Date1  Item1  Item2  Item3

Firm3               Date1  Item1  Item2  Item3

I would like to thank for your consideration in advance.

Best,
Rado


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