Tribune Media Co., one of the largest U.S. TV station operators, has launched an auction to divest its digital and data business in a sale it hopes will fetch at least $800 million, according to three people familiar with the matter.

The move represents the first asset sale by Tribune Media after it announced in February that it had hired investment banks Moelis & Co. and Guggenheim Securities to explore strategic alternatives. The company, which has a market capitalization of $3.3 billion, owns 42 broadcast stations and stakes in the Food Network and job postings website CareerBuilder.

The digital and data unit, which includes the Gracenote business the company acquired from Sony for $170 million in 2014, collects and distributes content and data to music and online video services, cable companies and consumer devices.

The digital and data unit generated $53.2 million in operating revenue for the three months ended March 31, according to Tribune Media's latest earnings release. It represented 11 percent of the company's consolidated operating revenue last year.

The asset could appeal to private equity firms as well as other companies in the sector, the people added. The process is expected to wrap up at the end of the summer or early fall, one of the people said.

While Tribune is exploring a sale of this unit, it could decide to also shed other parts of its business as part of its strategic review, the people added, asking not to be identified because the sale process is confidential.

Tribune Media declined to comment.

Higher programming costs and a challenging advertising environment have put pressure on Tribune Media to rethink its strategy.

Gaining scale through acquisitions is not an option, because its broadcast stations in 33 markets already reach 44 percent of U.S. households, above the 39 percent threshold that the Federal Communications Commission would look at when reviewing a deal.

Gracenote is a large provider of television "metadata," data that helps TV viewers figure out what programming they are watching when they use digital TV guides at home. It also provides data to mobile devices that can identify which movies, TV shows or music are being played. Its data is also used by car and consumer electronic companies.

Gracenote acquired three sports data companies last year for $54 million to expand into services that provide schedules, statistics and player information.

It competes with companies such as Rovi Corp., which agreed to buy TiVo Inc. for $1.1 billion in April.

Tribune Media spun out its publishing business, Tribune Publishing Co., in 2014.

Variety reported last month that Tribune was preparing to actively shop some of its digital data assets, including Gracenote.