That completely sucks! I would be fuming if they had planned to put it on the market and not told you because all those open houses and open for inspections that you will probably have to do. It is so wrong that they can get away with that.

As far as the possibility of selling it to investors - they would probably be a lot better if they were advertising that it was tenated until whenever it is that your lease expires.

For your own information, in Queensland (and I imagine it wouldn't be that much different everywhere else) - if you have a term agreement (6 months or whatever you signed), they can't just kick you out. They have to wait until the end of your tenancy or possibly negotiate something with you. Just like you can't up and leave half way through, they can't kick you out either. They have to give you 2 weeks notice before the end of your agreement if they want you to vacate (may be more in other states).

If you are on a periodic agreement (no fixed term), they have to give you 60 days notice if they want you to vacate. So if your fixed term lease expires and you don't sign a new one or give you 2 weeks to vacate, it automatically switches to a periodic agreement and they have to give you 60 days in writing.

As far as renting out to you when there seems to have been a clear intention to sell but not informing you as such, contact your tenancy authority and ask them if it is okay for them to do it. I know it usually is if they decide during your tenancy to sell but if it was their intention beforehand and they didn't tell you, I wonder what your entitlements are.

Grrr to the agent. It is wrong that they do this to people. What happened to 'peaceful enjoyment of the property' as one of the terms of your agreement!