A "Big Four" bitcoin exchange in the world, the Bitfinex trading platform is currently in a beta phase (testing phase). The platform is owned and operated by iFinex Inc. (Bvi), and during this final phase the platform is being prepared to operate under a fully licensed model.
The exchange part works like any regular bitcoins exchanges: you put your offer to buy or sell bitcoins. When an order is matched against another, it is executed.
The exchange wallet type is used for this feature.
Their margin trading feature is unique in the Bitcoin world. Basically, it allows you to borrow funds from lenders (see next feature) to trade bitcoins. If you make a profit, you get the profit and pay the depositor interests. If you make a loss, you reimburse the depositors the whole borrowed amount + interests. 
Their lending feature goes hand to hand with the margin trading feature described above.
If you don't feel like a trader and/or prefer safer investments, this feature is for you. Bitfinex allows you, using your deposit wallets, to lend bitcoins and/or dollars to traders. You can put offers with your chosen terms (which rates, for how long, and how much). When an offer is taken by a trader, the money in your wallet will be used to buy or sell bitcoins, and a loan will be opened. When the loan expires (the trader closes his position), bitcoins are bought or sold back and money is reimbursed to your wallet.
|Volume||Maker fees||Taker fees|
|>= 0 BTC||0.1%||0.2%|
|>= 500 BTC||0.08%||0.2%|
|>= 2000 BTC||0.06%||0.2%|
|>= 5000 BTC||0.04%||0.2%|
|>= 15000 BTC||0.02%||0.2%|
|>= 25000 BTC||0||0.2%|
Bitcoin: 0 International wire: 0.1% (minimum $20.00) EgoPay: 0.2% (not include charge by Egopay)
Bitcoin: 0 International wire: 0.1% (minimum $20.00) EgoPay: 0 (not include charge by Egopay)
Charged on your existing swaps, paid by the liquidity provider: 15.0% (of the swaps generated by active contracts)
Bitfinex Limited has its office in Hong-Kong, with one of our associate living there.
- Bitstamp web site