If you hold bonds in a taxable account, consider the tax - exempt funds instead of the total bond market index funds. (noroboinvestor.com)
The easiest way to do that to invest in a total stock market and a total bond market index fund. (realdealretirement.com)
Additionally, you might choose an array of bond market indexes, commodity indexes, and indexes that focus on international securities, which all have different risk profiles. (capitaloneinvesting.com)