A lot of IXC coins may actually be sitting in BTC-E wallets! People may have not even bothered to withdraw them when they closed down IXC 2 years ago.
btcguild used to run an ixcoin pool before merge mining. when they shut it down they gave miners a week to withdraw the funds. after that they deleted the wallets. i'm sure there were a lot of coins in there then.
Well, deleting wallets will definitely cause a lot of coins to disappear. Do you know when this happened and for how long was BTCGuild was merge mining iXcoin?