One of the biggest challenges for first-time homebuyers is the tightening inventory in major markets.

Inventory remains tight nationwide, with the number of homes listed for sale on Zillow down 0.4% annually in April, even as home values fell modestly month-over-month, according to the April Zillow (Z) Real Estate Market Reports.

After rising at the end of 2013, for-sale inventory has fallen for four straight months to begin 2014. Inventory is down compared to last year in 21 of the nation's 35 largest metro areas covered by Zillow, with the largest inventory declines in the Houston (26.6%), San Antonio (23.7%) and Boston (23.4%) metro areas.

More than half of metros in the U.S. currently have fewer homes for sale than at the same time last year. In many metros, inventory is tightest in the lower-end of the market, which represents the homes most commonly sought by first-time homebuyers....continue reading.