Amazon.com Inc. drew attention from landlords in March when it leased most of a 36-story downtown Seattle tower built during the recession, a sign that technology job growth would help lift U.S. office rents and occupancies.

"The reduction of big blocks of space is always the first indicator of recovery," said Patrick Callahan, chief executive officer of Urban Renaissance Group, a Seattle-based commercial real estate developer and investor that manages about 2 million square feet (186,000 square meters) of properties.

The U.S. office market gained 3.7 million square feet of net occupied space in the three months through June, the third straight quarterly increase, Reis Inc. said today. Vacancies fell or were unchanged in nine of the 10 largest office markets, and declined in more than half of the 79 metropolitan areas surveyed, the New York-based property-research firm said.