John Simon is a Managing Director at Sigma Prime Ventures who co-founded General Catalyst (now a major U.S. venture firm), led medical device company UroMed from founding to IPO, and co-founded the GreenLight Fund, which applies venture-style methods to scale proven nonprofits across multiple cities for poverty alleviation. He focuses on backing founders with world-leading domain experience at formation or earliest stages, emphasizing the need for evidence of customer demand before seeking capital—an approach informed by his own experience building UroMed through customer validation and scaling it to a several-hundred-million-dollar public company.