From the event website:
HBS Alumni Angels started in 2007 as a special interest group of the HBS Alumni Association of Northern California. Similar groups formed around the world and HBS Alumni Angels became a global alumni organization in December 2010. Internationally, HBS Alumni Angels members have invested in over 100 companies since 2007. Today, the HBS Alumni Angels organization is comprised of Harvard alumni interested in investing in high-potential early stage companies. HBS Alumni Angels is open to all Harvard alumni and others affiliated with the university, not just HBS graduates.
Attendance is by invitation only and exclusively for members of the HBS Alumni Angels and their invited guests.