I'm not sure what you mean & the snapshot isn't helping me much.
You probably know that you can have (or not have) Sub Totals for each value in the 'Row' area & you will get an overall 'Grand Total' at the bottom of the pivot.
Is it the Sub Total you're talking about when you say 'overall acomulative sum'?
no. it's not the sub totals that I'm looking for
What I want is every cell (in the second table) to be the sum of all the top-left cells (of the first table)