WPP PLC's stock experienced a significant plunge of around 15.94% in the pre-market trading session on Thursday.

The advertising giant's shares tumbled after it reported a steeper-than-expected drop in its fourth-quarter revenue less pass-through costs, which declined by 2.3% on a like-for-like basis. This performance missed analysts' expectations of a 0.2% decline, as the company faced challenges in North America and China due to account losses and economic pressures.

Additionally, WPP's outlook for 2025 further dampened investor sentiment. The company projected that its like-for-like revenue less pass-through costs would range from flat to a 2% decline, falling short of analysts' forecasts of a 1.8% rise. The weak guidance reflects the ongoing headwinds faced by the advertising industry, including the rise of generative AI and the growing dominance of tech giants in the market.