<prompt> Human: I usually hear that its easiest to rebalance around once per year, but easiest isnt always best. Is there an accepted answer for the most efficient way and timeframe to rebalance your portfolio? In this case, everything is being done in a Roth IRA and there are no transaction fees, so the only consideration that matters is how it will affect returns.  <response>: Lots of studies out there, but not much definitive in terms of whether any plan is better than others. Some people prefer rebalancing bands where you set the asset allocation your prefer and a few percentage point band around it. When market movement puts you outside the band you rebalance, so time isnt relevant. Others prefer an annual rebalancing, or every 18 months or so which seems to allow hot streaks to run just a bit and did slightly better in some studies.Conclusion: No clear answer what is best. Just pick one and stick to it. 