After what has been nearly a four-year slump in the US apartment market, the industry sector has started to show real signs of improvement.

The vacancy rate for the top 64 metropolitan apartment markets in the U.S. fell to an average of 6.6% in the first quarter, from 6.7% in the fourth quarter and 7.1% in the same quarter, a year-earlier. This is according to new quarterly statistics from Reis Inc., a New York-based property research firm. Rents also rose in the quarter.

"While absorption [during the first quarter] may seem modest, its important to remember that the apartment market has been plagued by negative absorption during the first quarter of each of the past few years," says Lloyd Lynford, chief executive of Reis. "Coupled with effective rent growth of 0.6%, [the results] represent good news."