mixed Investment property principal residence

My sister and I bought a 2-bedroom condo 8 years ago in Illinois when we both expected to work and live there.  My sister did get her job there and live in the condo since, but I ended up working and living in NYC.  Last year we sold the condo at a loss.  My sister can't deduct her loss because the condo had been her principal residence.  But how about me?  It was neither my principal residence nor my second home (I have never owned any other property),  Can I treat my share of the condo as investment property thus reporting my loss just like my long-term stock gains/losses? Any suggestion or guidance from the community would be greatly appreciated.