JWT Group will lose money in fourth quarter.

The parent of the troubled New York ad firm, J. Walter Thompson Co., said that it expects to report later this month an unspecified net loss for the fourth quarter ended Dec. 31. In 1985’s fourth quarter, the company earned $8.1 million. The company also projected that full-year earnings for 1986 will be only one-third of its 1985 level of $18.5 million and forecast that its first quarter of 1987 would be “weaker” than the same period in 1986.