Just had a call with one of the founders. Basically they allow startups (after being vetted) to IPO and sell their shares on the open market. It seems to have some similarities to crowdfunding, except for it being more transparent and having the benefits of a regulated market.
P.S.
Official name is Startup Stock Exchange (with spaces), but that name was too long for the submission form.
Vision Directory
Hustle X
Vision Directory