In recent years, the rise of robo-advisers has provided a new, potentially more cost-effective approach for offering financial advice. Using unique data from a large German retail bank, we investigate the effects of robo-advisers on clients' portfolios. We find that after joining a robo-advising service, clients increase financial risk-taking, hold more diversified portfolios with a larger fraction of index funds, exhibit lower home bias and trend chasing, and increase their (buy) turnover. These effects are generally stronger for former self-directed investors than investors who have previously worked with a human financial advisor. Investors also learn from the robo-advisory tool, as their portfolio efficiency improves also in the non-robo advised part of their portfolio. Our research can help understand the trade-offs associated with using robo-advisers.