The only thing i can think of is to use fixed assets for this and the you can revaluate the fixed asses class of stocks once a month or so.
Probably not an ideal solution but it should work.
I have never heard of any add-on that covers this kind of functionality for BC.
I think i would just let my brooker keep the records and just post monthly fluctuations to my G/L. Based on the figures from my broker.
That is how i solve it in the companies i am involved in.
