Ken Griffin, the founder of the hedge fund Citadel and the market-making firm Citadel Securities, currently oversees $71 billion in assets. Griffin’s career began in the 1980s while he was a student at Harvard University, where he reportedly started trading from his dormitory room. Over the past four decades, he has built a financial empire that plays a significant role in modern market infrastructure.

Griffin is frequently characterized by his willingness to act as a 'rescue buyer' during periods of financial instability. This strategy involves deploying capital into distressed assets or firms when other market participants are retreating. His dual role—managing a massive hedge fund while simultaneously operating a high-frequency market-making firm—has made him a central, albeit sometimes controversial, figure in the architecture of Wall Street. While his supporters point to his ability to provide liquidity during market panics as a stabilizing force, critics often raise questions about the potential conflicts of interest inherent in his firm’s business model. The scale of his operations means that his firm’s trading activities are often scrutinized for their impact on retail investors and broader market volatility.