Keystone gains 1.7 million square feet of existing office space and significantly expands its presence in the Keystone state with the transaction. Keystone, founded in 1991, has its headquarters in Bala Cynwyd.

Keystone plans to modernize the office portfolio, and the partnership will seek to develop the three land parcels – located in Lester, Media and Berwyn. The properties can accommodate future development of up to approximately 162,200 square feet in total.

“Our strategy is focused on realizing the full potential of these assets through the creation of vibrant, urban-inspired settings within the context of suburban office campuses,” said Bill Glazer, Keystone's president.

He said the Pennsylvania market is starting to show positive growth, with increased occupancy and positive net absorption. Meanwhile, Glazer noted, there is virtually no new office space coming to market. “As a result, we anticipate increased demand for modernized office space in core markets, and are well-positioned to fill this demand,” Glazer said.

The office properties in the portfolio are located in key submarkets, several of them situated along Pennsylvania's Main Line. They include:

• 150 Monument Road, Bala Cynwyd,125,783 square feet
• Four buildings at 1000 – 1235 Westlakes Drive,in Berwyn's Westlakes Office Park, totaling 444,350 square feet
• Three buildings at 4 & 5 Sentry Park in Blue Bell, totaling 193,930 square feet
• Three buildings at 100 – 300 Stevens Drive in Airport Business Center in Lester, totaling 371,000 square feet
• 1000 Madison Avenue in Lower Providence, 100,700 square feet
• Two buildings at Rose Tree Corporate Center I & II at 1400 N. Providence Road in Media, totaling 260,000 square feet
• One Plymouth Meeting, 502 W. Germantown Pike in Plymouth Meeting, 167,748 square feet

Mack-Cali will participate in management fees for the portfolio and a percentage of value creation above certain hurdle rates.

“This is an important transaction for Mack-Cali,” said Mitchell E. Hersh, president and CEO of Mack-Cali, which has its home in Edison, NJ. “It allows us to redeploy the proceeds from this sale into our multi-family platform while participating in the upside potential of the PA portfolio.”

The portfolio sale is the third transaction between the two companies as part of Mack-Cali's strategic diversification into the multi-family sector. Mack-Cali previously sold Moorestown Corporate Center in Moorestown, NJ and 16 and 18 Sentry Park West in Blue Bell to Keystone.