"We do have an understanding with AMAG Pharmaceuticals for that building," confirms Boston Properties VP Stacey Baker. While stressing that a deal has not been signed, Baker concurs that AMAG is concentrating its energies on 100 Hayden Ave., one of 10 Boston Properties assets in Lexington, including three on Hayden Ave. Built in 1985, 100 Hayden Ave. has attracted several top tenants over the years, notes Baker, including Harvard Pilgrim Healthcare, Raytheon and, most recently,VistaPrint, a high-flying digital technology company that expanded to another Lexington complex and is now seeking even more space in the region.

"We're very excited," Baker says about the prospect of AMAG Pharmaceuticals joining the esteemed list of 100 Hayden Ave. tenants. Founded in 1981 by an MIT professor, the erstwhile Advanced Magnetics has slipped recently, but new products have enabled the firm's stock price on Nasdaq to soar from $11 to more than $45 per share since 2005. "They are a real success story for Massachusetts," says one broker familiar with the firm. AMAG has offices at 61 Mooney St. and 125 CambridgePark Dr., both in the city's Alewife submarket.

AMAG is represented by David Townsend and Mark Roth of Cushman & Wakefield. Roth declined comment on the negotiations when contacted by GlobeSt.com, but did praise 100 Hayden Ave. as "a great building" in suburban Boston. The landlord recently embarked on a capital campaign that included improvements to the lobby, says Baker, while the availability to secure such a large block of contiguous class A space is also seen as another plus in the building's favor.