Just like when Obama attended that dinner in L.A. where some Nation of Islam dude gave a speech about hating Jews. Those recordings were never found either and I think some big republican wheel offered $100,000 for it IIRC.
The LA Times has the recording and still refuses to release it after 8 years.
Except that at a WallStreet confab, there's a chance that a goodly percentage of attendees are not down for the cause.