He has a stake in Bitstamp (an exchange) and, from the sound of it, one or two other blockchain companies (he seems to have a close relationship with Joe Lubin, the founder of ConsenSys so they are very likely Ethereum-based startups). The rest is assumed to be invested in the currencies themselves.

I was at the panel discussion and he seems wayyyy more excited about Ethereum - I wouldn't be surprised if he held more ether at this point (which is probably why he was so enthusiastic).