beppington
Elite Member
I would just add that a portfolio likely will require rebalancing periodically to maintain the desired asset allocation. That's one of the reasons I like the all-in-one mutual funds from Vanguard, Fidelity, T. Rowe Price, and others. They do the rebalancing for you.
With regular monthly or twice monthly additional investments, you may be able to re-balance that way, as you go along, depending on your portfolio's total value & how much you contribute each time. If your regular additional investments aren't enough to re-balance, especially combined with market swings, & you feel the need to re-balance, expert advice says not to do it any more than annually, & bi-annually is probably better. For most it costs $ to re-balance, in transaction fees (depending on your account & investments) &/ or taxes (again, depending on your account & investments).
They do the rebalancing for you.
I like to handle re-balancing (& anything else I can) myself. So, I stick to Vanguard index mutual funds, but not the all-in-one type.