Spencer Platt | Getty ImagesShares of Robinhood rose in extended trading Wednesday afternoon after the retail brokerage announced stronger-than-expected first-quarter results.Robinhood reported net income of $157 million, or 18 cents per share, for the first quarter. That is a positive swing from the same period last year, when the company had a net loss of $511 million, or 57 cents per share.Here's how Robinhood's results compared with Wall Street estimates, according to analysts surveyed by LS...