Crypto markets have gotten a shot in the arm this year from the U.S. Securities and Exchange Commission's approval of an exchange-traded fund to track the spot price of bitcoin and more recently, ether, the second-biggest crypto token. Shares in the crypto exchange rose 2.2% in extended trading after results. Coinbase's total transaction revenue climbed to $780.9 million in the second quarter, compared with $327.1 million in the year-ago quarter.