Coinbase is set to join the S&P 500, replacing Discover Financial Services, with the change effective before trading on May 19. The announcement comes as Coinbase's shares surged 8% in after-hours trading, despite its stock being volatile and underperforming this year compared to bitcoin. Additionally, Coinbase recently reported a net income of $65.6 million and plans to acquire crypto derivatives exchange Deribit for $2.9 billion.