That $1 billions worth of transactions, are they one year's worth of transactions, or accumulative over a number of years ?
With that size of transaction, it will be worth your while to seek advice from one of the big 5 accounting firms.
For tax purposes, are you an investor or a trader ? Answer to that will determine whether you can claim the GST Inout Tax Credit.
If you are a trader (viz, carrying on the share trading business as an enterprise), and if your turnover exceeds $75,000 (excluding the GST component), you are required to register for GST.
As you can see, there are quite a few considerations to take into account.
