While good points have been made i think you need to look past all that.
If you had a managed protfolio 5 IPs with separate loans, and one got a margin call what would be the result?
You either come up with the extra $$ or get foreclosed.
If you get foreclosed and the bank realises a loss, then you either pay up the shortfall or go bankrupt.
How will this foreclosure (which looks like a default) affect the rest of your the loans?
Will it give the other banks the right to call in their loans also?
Maybe you have an LOC to draw on and make up the difference in LVR.
So you have just increased you total LVR, meaning a higher interest payment.
If it's a portfolio of <1mil, you can pack shelves at Coles to make up the interest increase. If your portfolio is >5mil, then it may not be so easy.
Maybe you use the LVR to make up the bank's loss.
You have now lost all the $$ put in the deal + the banks loss.
Still increased LVR, and less income to pay interest if it was +cf CIP.
So higher LVR and higher expenses.
It's hard for people to think about this stuff before it happens because of the "only happens to others" syndrome.
Which is why I agree with sash and have always posted about having & building equity.
Unless you build equity your working for someone else.
But more than else i agree with his very profound 4th point...