Stock Portfolio Control ! Can i use the column that I am creating on the same calculation?

Hello Edhans, thanks for your reply.

I will try to time more details, but I also put a sample of the data on this GoogleSheets Spreadsheet so you can see the calculations that are being made : 

https://docs.google.com/spreadsheets/d/1PFA5f9yeq8D02Hz4R6HVeFnemuQgYn5zuEidyzcfujY/edit?usp=sharing

In Brasil, in order to pay your taxes, you have to know your Cust of acquisition of your stocks.

I was not very accurate in the Translation.  It is not the median or a simple average. 

I think the term that best describes what I am looking for is a weighted average of the costs ... but with a few rules.

Let's go to the example ;

Day 1 :  Buy 100 of stock A    for 10 .  Cost= 10 * 100 = 1000 .  Quantity =100.

Number of stock in portfolio =100

 PM ( what I am looking) = Cost/Quantity = 10

Day 2 : Buy 200 of stock A for 20 . Cost =20*200 = 4000 . Quantity =200 .

Number of stock in portfolio =300

PM =  (Previous Pm* Previous Number of stock) + (Cost  ) / number of stock

(( 100  *100 ) +4000 ) / 300    = 16,666

Day 3 

Sale of 200  of stock A.    THE PM is not affected by sales. Now you have 100 stocks in your portfolio with a PM of 16,666 . 

On this line, you can just repeat the Previous Pm or you can do the calculation:

PM = ( (Previous Pm* Previous Number of stock) + ( (- Quantity sold) * Previous Pm) /Number of stock

     ( (16.66 * 300) + (-200 *16,66)) /100

 PM = 16,66

I hope it has all the details now. I think the link with the date makes it easier to follow.

I need to do this only in PowerQuery .

The raw data has more rows with different stocks but they are in order ( first will appear all the operations of one stock before the next. I think with just this dataset is possible to help me.

Final question just to be sure. I cant refer to the same column that I am creating on the same step right?

Thank you very much.