WPP, the British advertising group, has lowered its full-year outlook for 2025 due to weaker-than-expected client spending and a decline in new business. The company now anticipates revenue to fall between 3% and 5%, a downward revision from its previous forecast of flat to a 2% decline. In the second quarter, sales dropped as much as 6%, reflecting challenges from fewer new clients and reduced advertising budgets amid economic uncertainty. This marks WPP's second profit warning this year. The stock has plunged to its lowest levels since the global financial crisis, with declines reaching up to 18% in some markets. WPP is responding by restructuring and investing in artificial intelligence to improve competitiveness. The profit warnings and share price declines underscore the difficulties faced by the advertising sector as it contends with macroeconomic pressures and the disruptive impact of AI technologies.