A start-up firm that sells extensive deal-by-deal data on commercial-property leases has raised another $4.45 million in funding and plans to expand to about 10 U.S. cities by the end of 2013.

CompStak Inc., which raised $1.24 million in its first funding round, got the new money from a group including Canaan Partners, 500 Startups, Founder Collective and Expansion VC. CompStak launched in Manhattan in early January and recently expanded to the San Francisco area.

CompStak charges landlords, asset managers and others more than $20,000 a year for access to its database on "comps," deal-specific data on rents, escalation clauses, landlord concessions and other lease provisions. While some of this information is confidential, brokers have informally traded it for years to make sure they are on top of market trends.

CompStak gathers this deal data from brokers and others by offering them, in exchange, access to comps on other deals. "We've been surprised how quickly brokers, researchers and appraisers have embraced what we do," says Michael Mandel, CompStak's chief executive.

—Peter Grant