Housing inventory has fallen by nearly one-third in the Denver metro area across all three price tiers during the past year, according to a study released Thursday by Zillow.

Contrary to other similarly affected metro areas, the inventory reductions in Denver are fairly even across the board. Inventory for all homes in the metro area dropped 31.7 percent. Inventory fell 32.3 percent in the bottom-price tier, 32.5 percent in the middle tier and 30.8 percent in the upper tier.

Nationally, inventory rates fell 19.4 percent across the three price tiers, declining the most (22 percent) in the upper tier.

With inventories down and demand up, home prices are on the rise — a positive sign for the housing market. But that can make it tough on homebuyers, especially first-time buyers.

The Zillow study said inventory of lower-priced homes, which are commonly sought by first-time homebuyers, dropped by 42.7 percent in California, including 59.7 percent in Fresno, 55.4 percent in Sacramento and 53.2 percent in San Francisco.

"First-time homebuyers are being squeezed out of the market by falling inventory and the rapid influx of investors looking to buy basic homes to rent out to the growing population of people who have recently been foreclosed upon," said Stan Humphries, Zillow's chief economist. "Investors are paying in cash and can close sooner, which is more favorable to banks and homeowners looking to sell."

Out of the 101 metro areas covered in the report, inventory across all tiers dropped the least in the Hartford, Conn. (4.6 percent), Albuquerque (4.9 percent) and New Haven, Conn. (5.5 percent) metro areas, and rose in only one market — Little Rock, Ark. (0.4 percent).

In the 30 largest metro areas, inventory across all tiers fell the most in Sacramento (42.4 percent) and fell the least in Cincinnati (9.5 percent).

The Zillow analysis tracked changes in the number of homes listed for sale on Zillow across the country as of Sept. 30.

John Mossman: 303-954-1479, jmossman@denverpost.com