Negotiations are underway to lease 45,000 square feet of space at Boston Properties’ Discovery Town Square, which would bring the two-building complex to 98 percent capacity.

During the company’s quarterly earnings conference call Wednesday, BXP President Douglas Linde announced the negotiations to shareholders.

“There are a number of technology companies looking to expand in Reston Town Center, just as the defense contractors have begun to retreat,” Linde said.

The previous lease on the vacant space expired in June, Linde said.

Discovery Town Square consists of two nine-story office buildings at 12010 and 12012 Sunset Hills Road. Companies currently there include SAIC and Microsoft.

Linde also told investors Boston Properties is “hotly pursuing” a 600,000-square foot build-to-suit lease agreement at Reston Town Center.

“Our new transaction activity is as robust as it has been in our history,” Linde said.

BXP’s second-quarter funds from operations per share ($1.67) and total revenue ($657 million) both exceeded expectations.