As the housing crisis worsened, foreclosed properties littered the landscape.

Last year, however, large investor groups began purchasing distressed single-family homes in bulk, then sprucing them up in order to ready them for the rental market. One of the biggest players in this new market is Blackstone Group (BX), which shelled out over $2.5 billion last year to buy 16,000 dwellings to add to its rental portfolio.