London—Citing concerns about the global economy, marketing intelligence company Warc has revised its global ad spending forecast to 4.4% growth this year, down from an April forecast of 5.3% growth. For next year, Warc lowered its global ad spending forecast to 4.9% growth, down from an April forecast of 5.4% growth. The fastest-growing ad medium this year will be the Internet, which Warc predicted will grow by 14.8%. Other media expected to grow this year will be TV (4.6%), out-of-home (4.0%) and radio (2.4%). Magazine ad spending was projected to be down 2.1%, and newspaper advertising will be down by 2.5%, according to the forecast.