Does CHCI have any convertible bonds outstanding? If so, maybe these shares are short due to convertible bond arbitrage? I really have no idea, but that is the only logical reason for that many shares short.
I think someone is trying to be smart and short housing because of rising rates. Also looking at the chart for the last 5 years, this stock has had trouble staying up once it spikes. They will find out that this time its much, much different. This short size has to be institutional on some level.