good shorting opportunity here......, page-12

Here is something pasted from this website I found- I hope it helps (intelligentinvestor.com.au/articles) 45 day rule - has to do with the franking credit limit of $5000 ( one lump sum or total doesn't matter), once you are above $5000 then you aren't considered a 'small' trader. won’t get any credits in respect of any shares that you don’t hold for either 45 days before the relevant ex date or 45 days after it (apparently 44 days before and 44 days after won’t do—no-one ever said the tax system made any sense).

Dividends are paid to shareholders who own shares before a particular day, known as the ‘ex date’. It then gets paid some time after that. If you buy the shares on or after the ex date, you won’t qualify for the recent dividend
Dividends are said to be ‘franked’ to the extent that they’re paid out of profits that have already incurred Australian corporation tax, and investors get ‘franking credits’ which they can set off against their own tax bill.