John Seo has found a unique way to profit from climate change and inflation. His hedge fund, Fermat Capital Management, is the world’s largest investor in catastrophe bonds, which are used by insurers to cover risks they cannot handle. What Happened: Seo, 57, has been trading catastrophe bonds since their inception. His fund, Fermat, operates in a niche corner of the financial market and has quietly amassed a $10 billion portfolio, capturing a quarter of the market, reported Bloomberg. Last year, the cat bond market saw a record $16 billion in issuances, bringing the market’s total size to $45 billion.