Bond guru Bill Gross told CNBC he is exiting one of his long-standing investments and is giving all the proceeds to charity.

That investment is rare U.S. stamps, which Gross has been collecting since 1993.

"There are limits at some point to a collector's portfolio because if pursued long enough and admittedly with enough money it's possible to fill in all the spaces in an album – in other words to get them all," Gross said in an interview with "Power Lunch."

"I figured it's better to give other collectors a chance to own some of these stamps and to use the proceeds for philanthropy."