DivcoWest and Boston-based Synergy Investments have completed their purchase of 71, 77 and 87 Summer St., a three-building office portfolio located in downtown Boston totaling 90,000 square feet of space.

The purchase price was $31.5 million, according to the Suffolk Registry of Deeds.

DivcoWest, which is headquartered in San Francisco, has been on a buying spree in Greater Boston as it pursues its strategy of acquiring office space in tech-oriented commercial real estate markets across the U.S. Earlier this year, it acquired the 114,240-square-foot One Winthrop Square in Boston and the 670,000-square-foot One Kendall Square complex in Cambridge.

Synergy’s downtown holdings include 101 Summer St., 99 Chauncy St., 100 Franklin St. and 294 Washington St.