The hot Phoenix area housing market is seeing slowing sales and a dramatic spike in housing inventories, according to a research report from Raymond James. Sales of existing single-family homes and condos fell 24% year over year in February, and listings increased 939% in the same period, Raymond James analyst Rick Murray wrote in a note to clients Monday. "As prices have stagnated since August, inventory levels have continued to grow, as we suspect an increasing number of speculators are placing their homes on the market," Murray wrote. From August to February, inventory increased by 122%, he noted. From a months-supply perspective, that means six months of inventory were on the market at the end of February, compared with 1.6 months in August. Median home prices remain 33% above the period a year ago, though they dropped 1% from August, to $253,000 from $255,000. TheStreet.com noted the dangers that lay ahead for Phoenix back in October . "It is clear speculators have headed for the exists in Phoenix. Given the increase in mortgage rates recently, it would seem as if this market will continue to face increasingly more challenging conditions, especially in light of the enormous surge in inventory," Murray says. D.R. Horton ( DHI), Pulte Homes ( PHM) and M.D.C. Holdings ( MDC) hold the highest market share in Phoenix.