I had the same question a couple of months ago and called the ato - they said you can "nominate" at tax return time which ones you are selling/sold (e.g. the ones you bought last week, or the ones you bought 2 yrs ago), but once nominated you can't change it. Does not have to be fifo. Good for me cos I have an old parcel and a new parcel. Based on this I have traded the new parcel a couple of times, but have left the old parcel.
cheers MD
ps - chockers :)
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