From viral jogging videos to advocating for new investment approaches, Blackstone President and COO Jon Gray is transforming a private equity giant built on exclusivity. Blackstone, once a fortress for the world’s richest institutions, is remaking itself under Gray into a financial superstore for the dentist, lawyer and teacher next door. As Chief Executive Officer Steve Schwarzman steps back from much of the day-to-day management of the $1.2 trillion firm he built into a private equity giant,