Artificial intelligence has become the defining investment story of the past two years, lifting stock markets, creating trillion-dollar companies and driving unprecedented demand for advanced chips. However, billionaire investor Ray Dalio believes the excitement surrounding AI is also showing familiar signs of a market bubble. The founder of Bridgewater Associates said while speaking to Bloomberg Television on Wednesday that investors should be careful not to confuse belief in the technology with belief in the stocks tied to it. His warning comes at a time when AI-related companies are among the biggest winners on Wall Street, with investors pouring billions of dollars into chipmakers, data-centre operators and AI infrastructure firms.