Day traders' hoorah-it's-the-weekend lounge January 13 - 15, page-58

An ABN is just a business identifying number .
You say you have made many trades per year ?
In what entity ?
-Your own name ?
-A company ?
-A self managed super fund ?
-A family trust ?

Each of these entities have differing taxation benefits or compromises .

If you want to be a trader in the eyes of the ato then remember gains can offset losses in the year . At June 30 your portfolio is valued and any gains / losses in value whether sold or not is to be included in tax return . The portfolio value starts again on July 1 for any gains or losses in the year .

( or at least I think so - not advice )