Office rents at the highest-quality assets in the city are beginning to spike while the rest of the market lags behind.

And there is one group to thank.

Rents for trophy office space hit a two-year high across Greater Boston, according to JLL third-quarter data.

The rates are being bolstered by law firms, which remain among the most active tenants in the market. These groups are willing to pay a premium for trophy space and often fill the nicest, newest buildings. With no construction expected in the near term, existing luxury space has a long runway of rent growth.

Top-tier average rents for high-rise buildings stood at $105.02 per SF in the third quarter, according to JLL, while average asking rents across the market decreased to $66.49 per SF.

"People are paying more for commercial real estate now than they ever have before at the top of the market," JLL Research Manager Bryan Montgomery said. "That's only going to continue and intensify."

The highest asking rents are coming out of the Back Bay submarket at close to $130 per SF, 15% higher than they were pre-pandemic, Montgomery said.

Back Bay achieved its previous highest lease rate in Q3 2025 at $121 per SF for space on the 31st floor or higher.

Downtown Boston has the second-highest rents and hit its high-water mark of $110 per SF in the second quarter of 2026, according to JLL.

Among the top deals last quarter, 10 law firms inked leases, with many relocating within the central business district. 

Greenberg Traurig took the top spot, signing an 82K SF lease at Hines' South Station Tower, relocating from Chiofaro Co.'s One International Place. Paul Hastings signed a 52K SF lease at BXP's Prudential Center, moving from the office REIT's 200 Clarendon St. property.

Other sectors are committing to high-quality space as well, including engineering consulting firm HNTB Corp., which signed a 77K SF lease at MP Boston's Winthrop Center. The firm plans to relocate from 31 St. James St., which is proposed for an office-to-residential conversion.

While the top of the market is beginning to benefit from the rent increases, the rest of the market is dragging down the overall average.

At the end of the third quarter, rents decreased 30 cents per SF to $66.49 from $66.79 in the same period last year, according to JLL. Overall Class-A rents decreased from $76.16 per SF in 2025 to $74.84 in 2026.

There are no new Boston offices in the construction pipeline, tightening availability across the nicest buildings.

High-rise availability in Tier 1 properties, which JLL characterizes as office buildings built in 2015 or later, fell to 3.2% by the end of the third quarter, according to JLL. Tier 1 mid-rise and low-rise space fell to 12.9% and 5.8%, respectively.

Some of the last office buildings to deliver in Boston were South Station Tower and Boston Global Investors' 10 World Trade office and lab development, which hasn't announced any tenants since opening in 2025.

And while shrinking vacancy and rising rents are spurring new office construction in markets like New York City and Washington, D.C., Montgomery said he doesn't picture development happening for years in Boston, as rents are nowhere near where they need to be to support construction costs within the city. 

"We're not going to see anything break ground by the end of the decade for sure," Montgomery said. "We're going to have to see some pretty explosive rent growth at the top of the market for something to happen in that 2030 to 2032 range."