The largest owner of lab space in the nation's premier lab market is spending close to $1B to add 400K SF to its portfolio.

Alexandria Real Estate Equities has agreed to acquire One Rogers Street and One Charles Park in East Cambridge for $815M, it disclosed in a Securities and Exchange Commission filing this month. The two buildings were sold just six months ago for $468M, the Boston Business Journal reports.

Alexandria plans to close on the buy in December, taking over the buildings from The Davis Cos. and Principal Global Investors, which are in negotiations with tenants to occupy 100% of the space, according to the filing. The office buildings will be partially converted into lab space with occupancy ready for the unnamed tenants expected in 2023.

The property has opportunities for future development, Alexandria said in the filing, and it adds to a footprint in East Cambridge of existing and pipeline properties for the REIT that is approaching 6M SF.

The sharp increase in price over the course of six months reflects the unrelenting push of investment dollars into life sciences space in Greater Boston. Cambridge remains the epicenter, with rents north of $110 per SF, even as companies are moving to areas like Watertown, Waltham and the Seaport in the search for more space.