I disagree, it's not that simple. this is the way I understand...

I disagree, it's not that simple. this is the way I understand it.  In the US shorting a stock that you already own will most likely create a tax problem for yourself.  It's a bit complicated but the jest of it is that you cannot delay any capital gains that you gained on the increase of the stock for the year. Example: If you own a stock the has gone up 50% in the year and you want to short the position to hold on to you gains. When you clear the short and you still have a 50% gain on the stock you then owe capital gains on that stock for that year. Also there will be interest on margin account for shorting. (you never own the stock you borrow so there is a cost to borrow.) Not sure how it works on ASX.

The other way to do this is using options (puts and calls) but all stocks do not have options available.