BOSTON-Stagnant vacancy rates and rent prices, favoring tenants in the broader office market, conceal intense competition for Greater Boston’s choice properties, a second quarter report from Richards Barry Joyce & Partners shows. Demand for class A properties and newly built spaces in 2Q11 fueled positive 353,000 square feet of absorption, reducing the region’s vacancy rate 0.2% from a peak of 16.5% in the years since 2008.

Market-wide vacancy and rental rates have remained constant for the past three quarters, though average rental rates for class A space in the CBD jumped $1.50 to $47, a return to 4Q10 levels from the past quarter’s dip, according to CresaPartners’ Q2 Tenant’s Guide. In select markets, high absorption reduced vacancy and drove up rent prices. High-end firms in those markets suffered a shortage of quality space.

In Route 128 West, office tenants absorbed 206,000 square feet in Waltham alone, more than any single market in Greater Boston, RBJ reports. Though Waltham’s vacancy rate is 24.2%, Brendan Carroll, RBJ’s SVP of research, says high-tech firms are competing over newly constructed properties built in the past five years, totaling 2.2 million square feet. The vacancy rate for those properties is just 1%. “The new product is completely gone,” Carroll says, predicting that landlords holding class B properties in Waltham will benefit from the supply shortage. “The demand will come down to you at some point.”

The same story is unfolding in Back Bay, which saw positive 97,000 square feet of absorption in Q2 and now has an 8% vacancy rate and 13.2 million square feet available, RBJ reports. High-end firms, like Latham Watkins, which moved into 29,000 square feet at the John Handcock Tower, often prefer space on the 20^th floor or above, which is scarce in Back Bay. RBJ reports that just 3.2 million square feet of such space is available, at a vacancy rate of only 1.8%. “That’s kind of a shock and awe number,” Carroll says. “It’s a very tight situation above the 20^th floor in the Back Bay.”

The big news of the quarter is that Vertex Pharmaceuticals received approval from the Food & Drug Administration for its Hepatitis C drug, the contingency the company’s massive office hinged upon. With the approval in hand, One Marina Park Drive at Fan Pier has commenced construction on the 1.1-million-square-foot build-to-suit for the pharma company, a real shot in the arm for Mayor Menino’s push for the Seaport District.

Additional reporting by Ryan Clark