Investment advisory services firm Cambridge Assoc. has signed on the dotted line to relocate into more than 170,000 square feet of office space at 125 High St. in Boston. The firm is scheduled to move into its new digs in January 2013. 

The firm is relocating its headquarters out of 100 Summer St., owned by Equity Office Properties (EOP).

The company’s 10.5-year lease at 125 High St., owned by Tishman Speyer, will start with rents in the high-$30s per square foot and move into the low-$40s over time, sources said. The firm will occupy floors nine through 15.

"It’s an example of a big tenant taking advantage of the leasing market downtown," an industry executive told Banker & Tradesman. "There are so few big tenants moving, the ones that are moving are able to get favorable lease terms and greater build-out allowances."

While rents differ greatly from the low to high floors, rents at 100 Summer St. average the low- to mid-$40s per square foot. Neither EOP nor Tishman returned calls seeking comment.

The property at 125 High St. totals approximately 1.5 million square feet and encompasses a full city block bounded by High, Oliver, Purchase and Pearl streets. The building was designed by TRO Jung Brannen and completed in 1991. With a footprint of 2.5 acres, the complex is composed of two office towers and a renovated 19th century building, all connected by an 11-story glass atrium.