"Availability rates are much more indicative of the health of the market," Don Hause, vice president at Spaulding Slye Colliers, tells GlobeSt.com. "They take into account all vacant space that is available, like sublease space."

According to Hause, there is now over 650,000 sf of sublease space in the Cambridge market, most of which did not exist 45 days ago. This includes Cambridge Technology Partners, which has 47,000 sf of space available; Zentropy Partners, which has 40,000 sf available; Rowecom, which has 21,000 sf available; and, Perot Systems, which has 47,000 sf available.

"These companies have either downsized or this is space they committed to, given how tight the market was but they never grew into," points out Hause. He adds, owners have not yet started significantly lowering rents here yet. "People want to see if this is an aberration or a trend," he says.