Bonds % in investment portfolio

[irishguy]

With a 20-30+ year time horizon is there any need to have bonds in an investment portfolio? If your a long term buy and hold investor of an all world equity etf, should you not solely invest in that one instrument?
Again assuming you have a few months cash in a rainy day fund and your not the type who would panic with large drops in your fund and moving into more bonds/cash closer to when you might need it i.e retirement

I have seen a number of portfolio makeups of 10-20% bonds. I assume that would mostly be a longer term store for a larger rainy day fund?

 

[Sarenco]

Ultimately it’s a personal decision which should be based on your need, willingness and ability to take equity risk.

However, there have been 20 and 30-year periods historically where domestic bonds have outperformed domestic equities in all developed economies.

Stocks for the long run?

It's commonly stated that stocks provide superior long-term returns to bonds. But what does "long-term" mean in this context? Over the last 20 years, the S&P500 has produced an annualised 4% return, with all dividends reinvested. That's an annualised real (after-inflation) return of less than...

www.askaboutmoney.com

Also, holding a modest allocation of bonds can reduce the volatility of an equity-heavy portfolio, with a modest impact on anticipated returns.