Low construction interest rates (3%) and high rental demand have helped pushed the Denver apartment market to one of the top five in the country.  Sales of Denver area apartments topped $2.4 billion in 2012 as private investors and investment companies are looking for cash flow and cash-on-cash investments. The average capitalization rates for Denver area apartments are between 6-7%. Capitalization rates are an indirect measure of how fast an investment will pay for itself and capitalization rates, or cap rates, provide a tool for investors to use for roughly valuing a property based on its Net Operating Income. Colorado Division of Housing reported the vacancy rate for Denver area apartments stood at 4.3% and rents increased 6% over last year.