U.S. apartment rents could rise 3.3 percent in 2014, little changed from last year, as the most construction in a decade boosts vacancies and limits landlords' ability to increase rates more, according to Reis Inc, Bloomberg reported. The 41,683 apartment units completed in the fourth quarter were the most since late 2003, the New York-based research company said in its quarterly report. Development rose from 29,560 units a year earlier and 37,546 in the third quarter.