I am a professional business analyst with 15 years experience and expert level Excel skills (including Excel development with VBA /Macros). I have a strong background in retail, and your sheet requires a really similar approach to calculating a weighted average cost on a perpetual inventory - something which I am extremely familiar with in Excel! I think the approach which might give you the flexibility you require would be to create a second sheet with a pivot table for your results, and then have the 'go' button change the source of the pivot table to the share data you just pasted in (as well as adding in the actual calculation for the trades). I would love to chat further about your requirements!