Office vacancies rose in downtown Los Angeles.

Among large cities, Los Angeles recorded the largest jump during the third quarter, to 17.5% from 15.9% the previous quarter and 13.5% in the third quarter of last year, according to Coldwell Banker. The Los Angeles increase was attributed to new construction with low pre-leasing of office space. Nationwide, downtown office vacancies slipped to 16.7% from 16.8% in the second quarter and 16.5% in the third quarter of 1985.