subtotal for a group

[cmk]

I have a database with stockholder information. It has a stock certificate
table that carries the orginal # of stocks purchased and I have a transaction
file that contains selling of the stock. The two files are linked by
stockholder, certificate number, and stock type

I am trying to get a subtotal of my ending balance of shares by stock type.
But I cannot figure out how to have a running total of my original purchased
stock shares by group stock type. Then another field with a subtotal of
total changes. If I can get those two numbers then I can sum them to come up
with an ending share balance by stock type

any help is appreciated thanks

 

[[MVP] S.Clark]

Running sums are super easy(bit switch) in Reports, but a pain in queries.