E*Trade would be one of the largest securities brokerages to allow crypto trading. It will enter into a competitive market with startups like Coinbase Inc., which have made names for themselves as go-to places for such transactions. Closely held Coinbase reached a valuation of $8 billion in 2018 and projected sales of $1.3 billion. Fintech startup Robinhood, most recently valued at $5.6 billion, has also added cryptocurrency trading as a way to woo millennial customers.