LOS ANGELES — Two Southern California billionaires who had signaled interest in buying the Los Angeles Times instead joined forces Wednesday in a surprise bid for the entire Tribune Co., the Chicago-based parent of the Times and other media properties.

The offer came from Eli Broad, a philanthropist who made his fortune in housing construction and investment services, and Ron Burkle, whose billions came from owning supermarket chains, according to a person familiar with the offer who was not authorized to publicly discuss it.

Further details were unavailable on the amount of the bid and whether the potential buyers would break up the company that owns 11 newspapers, including the Chicago Tribune, 25 television stations and the Chicago Cubs baseball team.

It also has sizable stakes in the Food Network and the online classified advertising venture CareerBuilder.

Broad declined to comment. A call to Burkle’s office was not immediately returned.

The bid came a day after Chicago-based Tribune replaced Dean Baquet as editor of the Times because he defied demands to make further staff cuts at the paper.

Broad and Burkle have long said they would be interested in returning the Times to local ownership.

A third billionaire, entertainment mogul David Geffen, is also known to be interested in buying the Times. A call to his office was not immediately returned.

Shares of Tribune were up 86 cents, or 2.7 percent, to $32.48 at the close of trading Wednesday on the New York Stock Exchange. Shares continued to climb in after-hours trading.