American Realty Capital Properties Inc. is interested in acquiring NorthStar Realty Finance Corp., people with knowledge of the matter said.

American Realty, a real estate investment trust, is weighing an offer of about $20 a share for NorthStar, one of the people said, asking not to be identified discussing confidential information. That’s a premium of 25 percent to NorthStar’s closing price of $16.03 last week and would value the company at about $6.5 billion.

There’s no guarantee that an agreement will be reached, one of the people said. NorthStar shares rose 7.6 percent to $17.24 as of 10:26 a.m. in New York today after the Financial Times first reported the discussions.

The deal would be American Realty Chief Executive Officer Nicholas Schorsch’s second major acquisition in less than a year. In October, the firm said it would acquire Cole Real Estate Investment Inc. in a $9.8 billion deal, including debt, data compiled by Bloomberg show.

Matt Goldstein, a spokesman for American Realty, declined to comment while Joe Calabrese, a spokesman for NorthStar, didn’t reply to two calls seeking a comment.