By Anne Steele

Sirius XM Holdings Inc. is near a deal to buy E.W. Scripps Co.'s Stitcher Inc. podcasting unit for around $300 million, according to people familiar with the matter.

The satellite-radio giant is working to expand into the rapidly growing podcasting industry, following similar moves by media and tech companies including Spotify Technology SA and iHeartMedia Inc.

Stitcher runs a free podcast listening app and a premium $4.99 monthly service that lets subscribers listen to podcasts without ads. It also owns podcast networks including Earwolf and Stitcher Podcasts. In partnership with outside networks and shows, Stitcher distributes other podcasts and sells advertising for them through its Midroll Media advertising unit.

Sirius generates most of its revenue from subscriptions to its satellite radio service but in 2018 agreed to buy internet-radio streaming company Pandora Media Inc. for $3 billion -- adding a business more reliant on advertising and with podcast aspirations of its own to its lineup.

Last year Sirius signaled its intent to expand its podcast business with a deal in which Walt Disney Co.'s Marvel Entertainment is creating exclusive podcasts for the company's satellite radio and streaming services.

U.S. ad revenue from podcasts rose an estimated 42% to $678.7 million last year, according to the Interactive Advertising Bureau, and is projected to rise to $863.4 million this year and exceed $1 billion by 2021.

Scripps bought Stitcher in 2016 for $4.5 million in cash and then combined it with Midroll Media, the podcast-advertising company it had acquired the year before for $50 million.

Write to Anne Steele at Anne.Steele@wsj.com