Offer your thoughts or opinion on the input financial query or topic using your financial background.

How to decide on split between large/mid/small cap on 401(k) and how often rebalance
I really like keshlam's answer. Your age is also a consideration. If you make your own target fund by matching the allocations of whatever Vanguard offers, I'd suggest re-balancing every year or every other year. But if you're just going to match the allocations of their target fund, you might as well just invest in the target fund itself. Most (not all, just most) target funds do not charge an additional management fee. So you just pay the fees of the underlying funds, same as if you mirrored the target fund yourself. (Check the prospectus to see if an additional fee is charged or not.) You may want to consider a more aggressive approach than the target funds. You can accomplish this by selecting a target fund later than your actual retirement age, or by picking your own allocations. The target funds become more conservative as you approach retirement age, so selecting a later target is a way of moving the risk/reward ratio. (I'm not saying target funds are necessarily the best choice, you should get professional advice, etc etc.)