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. Neither service limits the amount of bitcoins that can be traded assuming proper verification has been submitted. You can get in and out of coins fast at good prices. In addition, there are some other advantages of using a decentralized exchange. Just before the theft, Bitfinex was fined by the U.