By deciding to build their product within the guidelines of the Commodity Exchange Act, Coinbase has at least initially excluded a large segment of their user base. Other exchanges, like cex.io, offers margin trading to all users — but probably wouldn’t stand up to U.S. regulators. For Coinbase, moving slowly and maintaining a favorable relationship with regulators is necessary if the company wants to stick around. The company explained: “we’re committed to working with regulators as the blockchain space continues to develop, rather than take on unnecessary risk just to get features out more quickly. Some other digital currency exchanges have decided not to do this. For us, the best approach was to carefully design our margin trading feature and engage with the CFTC to make sure that GDAX remains compliant.”

https://techcrunch.com/2017/03/21/coinbase-has-added-margin-trading-to-its-bitcoin-exchange/