I allocate 6% of my portfolio to this. I expect some moderate growth (less than 5% per year). It should provide some cash reserve in the event of a bigger dip, which allows you to buy equities at a discount. Percentages that go as high as 30-40%of the portfolio in bonds are not for me. But there are 2 kinds of investors, those who say they can take a big dip, and those who have. So choose wisely.