James Rappaport

In the wake of Blackstone Group’s $39 billion purchase of 22 buildings, 17 of them in downtown Boston, tenants are facing dramatic rent hikes.

“There’s no question that Blackstone has been the leader in pushing rents,” said David Begelfer, chief executive officer of the Massa-chusetts Chapter of the National Association of Industrial and Office Properties “They are the major force in Boston because of the vol-ume of properties they own. They have the ability to take the lead in pressing rents and others will follow.”

In 2007, Blackstone, a private equity firm, set a record price when they purchased 11 million square feet of office space in Greater Boston from Equity Office Properties Trust. The sale echoed throughout the nation’s commercial real estate market and launched the “Blackstone Effect” where properties are sold not based on their worth, but on future rents that could be earned.

James W. Rappaport, chairman of the New Boston Fund, a real estate investment management firm, said skyrocketing rents might be good for landlords, but it could drive firms from the downtown. “Rents at $80 per square foot will make Boston uncompetitive,” he said. “There will be resistance from tenants and some might seek other options.”

Rappaport predicted that while many firms want a downtown address, they might flee to the suburbs for a better deal. In the 1980s, Fi-delity’s offices were in Boston, but in the early 1990s they moved some of their operations to Marlborough, Houston and Kentucky, he said. “All it takes is one big firm to bolt to break the market,” he added

While brokers declined to provide specifics about the increases, privately they say rents could double to $80 in some of the city’s pre-mier properties. Some of the buildings that Blackstone owns are: 100 High St., 150 and 175 Federal St., 500 Boylston St., One Post Of-fice Square, 60 State St., Center Plaza and 225 Franklin St.

Gregory P. Shay, president of Equity Office, the Blackstone unit that owns the Boston-area buildings, did not return a call seeking comment.

But Joseph Sciolla, managing principal at CresaPartners, an international commercial real estate firm with a Boston office that only represents tenants, said he doubts Blackstone can achieve any increases in rents amid Wall Street’s turmoil.

“The market has turned around in the last three weeks, rents have flattened and I expect some Class A office rents in Boston will fall,” he said. “Don’t forget that David Begelfer speaks for landlords, and they’re trying to keep rents up. But most of the landlord brokers will acknowledge privately that rents are falling.”

What’s Down Is Up

Mark Weld, managing director of ING Real Estate, disagrees. He said Blackstone is in the driver’s seat because the downtown va-cancy rates are in the single digits and the pipeline for new office space is at least three years away.

“This is purely supply-and-demand driven,” he said. “There is not much office space out there for big tenants so the fundamentals are there for strong rents. Tenants who are coming to the end of a 10- to 12-year lease where rents were $20-$30 in the best buildings in the Financial District can expect to pay a lot more.”

Begelfer noted that Blackstone is backing its boost in rents with tenant improvements. Last year, the largest owner of office space in Boston said they planned to spend $60 million on renovations on five of its towers.

“For years, the highest rent was at International Place,” he said. “Don Chiofaro, the building owner, was the king of going to the top end with rent. But now Blackstone is the price leader.”