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

Thanks for reply Edhans!

I will try to give more detail about the calculations.

I put some RawData in a google sheets so that you can see the formulas that I did to get the results :

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

I am struggling to do this in Power Query because I don't know how to use the Previous result( OF THE SAME COLUMN) in the formula of this same Column. Is that Possible in Power Query?

You are right. I don want the median value. Or the average. It was a problem in translation. This number is called "PM" in Brazil, and it is used to calculate some taxes that you have to pay in certain operations in the Stock Market.

I think what I want is more similar to a weighted average of the cost ( with the rule that a sale should not affect the PM)

Let me give an example.

Day 1 - Buy 100 of Stock A . Price = 10. Quantity = 100 Cost = 10*100 =1000
Number of stocks = 100
PM ( what i am looking for) = Cost/number of stocks = 100

Day 2 - Buy 200 of Stock A. Price = 20 . Quantity = 200 Cost = 20 * 200 = 4000
Number of Stocks = 300
PM = (cost of buy day 1+ cost of buy day 2 ) / number of Stocks
(1000+4000) /300 =16,66666

Day 3 - Sale of 200 StockA ( the price of the sale does not matter).
Number of Stocks = 100
A Sale event does not change the PM!
I can just copy PM before the sale =16,666 or you can use the formula:
(
(Previous PM * Previous Number of Stocks ) +
( ( -Quantity of Sale) * Previous PM * )
) / number of Stock

= ((16,66*300 ) + (-200 *16,66) ) / 100
=16,666

I hope the example and the data in the link can clarify what I want.

Thanks for all the help!

Feel free to ask another question ( I am stuck with this problem for more than 15 hours...)

ps: The data has more stocks. They are classified by stock ( all the operations from one stock appear before the next stock). I Think just the raw data is enough so I can apply the solution.