The article discusses the potential for a stock market bubble, with renowned investor Howard Marks suggesting that artificial intelligence (AI) could be the missing ingredient fueling excessive investor sentiment. Marks argues that while AI has the potential to drive productivity and economic growth, it could also lead to unrealistic expectations and overvaluation of companies in the AI space. He cautions that the hype surrounding AI may be creating a speculative frenzy, similar to past bubbles like the dot-com boom. However, Marks acknowledges that AI is a transformative technology that could have a significant impact on various industries. The article highlights the importance of maintaining a balanced perspective and avoiding excessive speculation when it comes to emerging technologies like AI.