NABIOJ was a $30 Nov 2004 instalment warrant.
Before NAB paid its 83c div on Nov 15, this warrant was trading at 83c (they werent silly enough to sell it any lower).
This provided a risk free trade.
You could have bought the warrant for 83c, held overnight and collected 83c cash div plus 35.5c franking credit (total 118.5c).
Once ex-div, the warrant was worthless, although a sharp NAB rally towards $30 would have created some value.
So you would have made a 43% return on your money, plus had free upside exposure.
Be on the lookout for short dated instalment warrants (trading at cash div value) around cum-div time.......