JPMorgan Chase & Co. is planning a sale of U.S. home-loan bonds without government backing, adding to evidence that the market for the securities is beginning to pick up steam.

The deal will be tied to $303.7 million of prime 15-year mortgages, according to a person with knowledge of the transaction who asked not to be identified without authorization to speak publicly. While most of the loans had original balances larger than the current threshold for jumbo mortgages, the market’s focus since its revival, 14.5 percent of the debt is smaller than $400,000, the person said.