Coinbase shares fell Thursday as second-quarter revenue came in shy of analysts' estimates. Gains in the cryptocurrency exchange's subscription revenue failed to offset weaker trading volumes during the quarter.In the quarter ended June 30, Coinbase net income rose to $1.43 billion, or $5.14 per share, from $36.13 million, or 14 cents per share, a year ago. Earnings in the latest period benefited from a gain $1.5 billion, including an unrealized one related its Circle investment, and $362 millio...