hitbtc is selling IOU ( The term "IOU" is an abbreviation, in phonetic terms, of "I owe you.") , real tezos ICO tokens are not distributed yet. Hitbtc has a price of usd $2 per IOU - that is aprx. 5x ICO price. When real tokens hit the market this price could be meaningless..or not 
Do you know if individual can sell Tezos IOU on hitbtc ?
it is a buy/sell situation, you can trade with them on hitbtc