Event study

Put this in Sheet2 B4 and drag right, down

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maybe a little explination is required

The INT(column/2) is because you go from one columns spread into two columns

The 1+(COLUMN()-1)*0.5*SIN(0.5*PI()*COLUMN())^2) is just and alternating sequence 1,2,1,3,1,4,1,5,1,6, etc. as you need to keep looking in Column A for the date and the stock prices in 2,3,4,5, etc.