Tara Siegel Bernard tells us that automatic rebalancing options are becoming common at 401(k) plans, but the service is still a rarity for online brokerages. TD Ameritrade and Fidelity are among the handful of exceptions, she reports in The New York Times. In a perfect world, these options would be standard everywhere. Rebalancing, after all, is crucial for risk management and earning a decent risk premium through time. Making this essential task easier, by putting it on auto pilot, would be a huge plus for investors.