Best for Active Traders: Coinbase Pro. Check if the exchange is regulated. Bitfinex is a popular exchange because in terms of USD trading volume it has the most liquidity. As soon as you click on the arrow sign in orange circle you will get 2 pop-up on the same page one saying to SIGN UP and the second saying to click on the link send to your email account to verify your email id for signup. Mycelium Local Trader helps you find local Bitcoin sellers. Just before the theft, Bitfinex was fined by the U. Buyers then usually receive their bitcoins within an hour.