As a 21 years old, I don't see a need to hold bond position in my portfolio as long as I can take the risk.(I'm 100% stocks, 95% invested)I have an ultra long term horizon (hence equities) will become my main way of investing. I diversify into both Income (REITS + Non-REITS) and Growth Stocks (Undervalued + Growth Stocks) so that I capture gains in a downturn and upturn. People like Warren Buffett and Peter Lynch do not own bonds in their portfolios because it is purely a hedge against market downturns, and weighs down your potential upside during uptrends. If you learn from history, you will understand that equities trend upwards in the LONG RUN (provided you have solid businesses). A full equities portfolio will almost ALWAYS beat a portfolio of bonds and equities in the LONG RUN. In conclusion: if you can sleep soundly at night knowing that your portfolio of stocks is down 20%-50%, not panic selling and just stay the course, go full equities. If you are unsure of your risk profile yet, go ahead and buy into some bond ETFs so that your portfolio won't fluctuate too much. When you become more confident, go ahead and sell those bonds and be as aggressive as possible before liabilities/expenses starts to set in in life. Also your portfolio should align with your own personality, risk profile and time horizon. Everyone is different. Different life stage requires different adjustments to your portfolio, I am merely speaking for myself as a young 21 years old investor. Please do your own due diligience!