Real estate investors from around the world have just laid down a huge bet on downtown Boston, snapping up a big chunk of the office market at sky-high prices. And if you or your company leases space in downtown Boston, you may just very well find yourself footing the bill for this gamble in the months and years ahead.

Blackstone’s sale of its Boston portfolio – a sizable chunk of the downtown office market – sets the stage for the biggest rent spike since 2007, when rents last peaked after soaring 44 percent, contends a pair of CBRE/New England experts, Webster Collins, executive vice president and partner, and Trevor Regensburg, a financial analyst with the firm.

By the time the dust settles, we could be looking at office rents in the $70 a square foot range – far above the 2007 peak, the duo predicts.

Simply put, the Canadian, Norwegian and Japanese investors who shelled out billions for some of Boston’s finest office towers are betting they can make back that money – and much more – through higher rents.

Gold Rush Downtown

Setting the stage for the big rent hikes to come has been a frenzy of office tower sales in the Financial District, Back Bay and Seaport over the last six months.

More than 5.5 million square feet of office tower space changed hands or has been placed under contract between July and September, Collins and Regensburg note in a piece for the New England Real Estate Journal. Another 4 million square feet has hit the market or is about to.

The buyers, in turn, have been a mix of international investors and big money New York firms.

Oxford Properties, which buys investment real estate for the government of Ontario, is one of the leading new investors in downtown Boston real estate.

Oxford forked over $2.1 billion to snap up four major Boston office towers and a prominent Cambridge address, including 100 High St., 125 Summer St., 60 State St. and 225 Franklin St. JP Morgan Chase & Co. teamed up on the latter two properties, as well as springing for a Rowes Wharf building.

Norges Bank Investment Management, an arm of the central bank of Norway, this fall bought a 45 percent stake in 100 Federal St. and Atlantic Wharf from Boston Properties, adding to its sizeable stake in One Financial Center, across from South Station. Norges previously purchased a large stake in Boston’s One Financial Center.

That’s a lot of new owners looking for a return after breaking the bank to buy into Boston’s pricey tower market.

History Poised For A Repeat

To see what happens next, one need only look at the last time there was a major shift in ownership in the downtown Boston office market, CBRE’s Collins and Regensburg argue. The last time there was a big rent spike in downtown Boston was back in 2006, when Blackstone snapped up the very same office towers that Norges, Oxford and others are now buying.

Like today, Blackstone spent big money to buy these towers, wagering it could make even more money by hiking the rents. Blackstone wasted no time, immediately bringing in their own leasing team and jacking rents “essentially overnight,” Collins and Regensburg write.

And for a short time, the strategy worked splendidly. Average asking rents for top downtown Boston towers soared from $41.76 per square foot at the end of 2006 to $60.15 per square foot a year later at the end of 2007, the pair noted.

But the gains proved to be short-lived, with the Great Recession hitting in full force in 2008, blasting a hole in the downtown office market and sending rents plummeting.

Now, after five years of recovery, office rents have recovered lost ground and then some. Asking rents at the best towers now top $50 a square foot – a big step up from the $42 a square foot office tower owners were charging back in 2006 before the last big rent run-up.

Office vacancy rates are also in similar territory, at 8.4 percent now compared to 8.3 percent 2006.

“All signs are in place for another major rent move rivaling The Blackstone Effect of 2007,” Collins and Regensburg write.

The two predict a surge over the next two years to an average of $70 a square foot for downtown Boston’s best office towers, a full $10 higher than the last peak in 2007.

Will Rent Hikes Stick?

Still, the big question is not whether a big rent hike is coming, but rather whether it is sustainable long-term.

Collins and Regensburg suggest it is, with the obvious caveat that the last run-up was short-circuited by the global economic meltdown of 2008, which sent both unemployment and the office vacancy rate soaring.

“At this point in time, with Boston being a 24-hour city with growing demand, rents projected herein are expected to be sustainable for a far longer period of time than that experienced in the past,” the pair contends.

Sure, maybe. But it won’t necessarily be an easy score for tower owners – corporate America has emerged from each recession in the past two decades leaner, meaner and tougher on costs than ever before.

Technology has also made companies across the spectrum, from tech firms to old-line law firms, less reliant on space-intensive office setups, with less and less tolerance for huge, walled-off offices that are rarely used.

And no one should rule out the possibility of another recession, though a 2008-style cataclysm doesn’t appear to be looming at the moment.

So welcome to Boston, all you investors from Canada, Norway and beyond! Grab your gains while you can. But remember, nothing is forever, including this golden moment in the Boston office market.

Email: sbvanvoorhis@hotmail.com