<prompt> Human: I suspect there are reasons, but it seems to me that if I dont need to draw down on my portfolio, I can ride out any bear market and leave it be, which to me sounds like the reason you want bonds in the first place. I do automatically re-allocate quarterly... do bonds help there? What else am I missing? I have a pretty basic tax situation and everything is in one 401k... about half is Roth and half Traditional.  <response>: Vanguard has a great page on this: portfolio allocation modelsAverage annual return: 100 stocks: 10.2 80 stocks, 20 bonds: 9.6Having 20 in bonds offers a lot of risk reduction for a rather low price. The closer you get to your retirement age, the more you will need to re-balance towards bonds as you cannot ride out the cycle. 