Simmons is the person behind the Sea Change Foundation, which is one of the biggest funders in the climate and energy space, giving out $55 million in 2012. He’s the son of James Simons, the math whiz who founded Renaissance Technologies and built the $12 billion fortune that bankrolls Sea Change. But it would be wrong to dismiss Nat Simons as merely an heir, since he’s also spent most of his career in finance - both at his dad’s operation and running his own investments.