In an industry known for its secrecy, Boston-based hedge fund firm Convexity Capital Management is even more secretive than most. Convexity, founded by former Harvard Management president and CEO Jack Meyer in 2005 with David Mittelman and Maurice Samuels, is a so-called "Crimson Cub," one of a handful of hedge fund firms with ties to the Ivy League university's endowment fund. Under Meyer's leadership from 1990 to 2005, HMC posted an average annualized return of 16.1 percent. That explains why Convexity was the largest hedge fund start-up in history at the time of its launch, pulling in a stunning $6.3 billion, including a $500 million investment from Harvard. Within two years Convexity became the 68th largest hedge funds in the world and has steadily increased capital ever since, aside from a two brief down years…