Have noticed on the mmxiv rich list wallet MZ6oAFWNZZuDFQWKRiJPJjc5obC3iiJrag is holding 802 coins over 1/3 of the coins total supply, Don't think that its bittrex wallet as amount dose not change, can't be good that someone is hording so much, hopefully in the future the amount gets broken up,
Actually I'm almost certain that is one of the Bittrex wallets. Exchanges wallets are funky, they are always moving coins in and out of several addresses, cold storage, etc.
That particular address may not have a lot of transactions but I'm guessing that's just one of many addresses Bittrex uses. Check the rich list again in a few days, I bet you'll see a different address holding those 802 coins.