Chicago--Tribune Co., the publisher of the Chicago Tribune and the Los Angeles Times, on Thursday reported a net loss of $139 million for the third quarter. The company cited an advertising drop, an expensive restructuring and costs of news coverage in the wake of the Sept. 11 attacks. The publisher also warned that the fourth quarter would fall short of current estimates because of ad cancellations and higher newsgathering, production and distribution costs. The net loss amounted to 49 cents a share, compared with 22 cents a share a year earlier, on profits of $79.2 million. Revenues fell 7% to $1.28 billion from $1.37 billion. The Chicago-based company, which owns 11 newspapers, 22 TV stations and more than 50 Web sites, has cut 1,700 jobs, or up to 7% of its work force, because of the advertising slump.