flyingangle,
when the stock moves to the new exchange it will be listed in whatever currency they use on that exchange. Our accounts here should reflect the proper currency exhange rate relative to the USD after conversion~
For example, if the stock is listed on the LSE at 10 BP, then the approximate USD value would be 15$, with the exchange rate the way it is now.
Each broker is different though, best to call and ask a few questions.
No matter though, it's easy to figure out the rate of exchange for any currency~
You can tell who's hit by who's hollerin'