They worked on software for big investment banks and have said that the Occupy Wall Street protests of inspired them to start a no-commission trading app. Take the time to make your initial product perfect before moving to the latest and greatest. This year is the tipping point when millennials will outnumber Boomers. Growth hacking is alive and well. The app has elements of fun, echoing in subtle ways the congratulatory elements of smartphone games that spur users to keep playing. These range from the complex and poorly understood, like payment for order flow in which dealers and exchanges pay smaller brokers a commission to route orders through their systems , to the simple: interest and fees.