100% equity portfolio - no sane person would go for this.
Over a 20 year period, Bonds have never outperformed stocks. IMO if you are in your 20's or 30's you should have 0% bonds (unless you're super rich i.e. trying to protect rather than accumulate wealth).
However above refers to the Equity portion of your portfolio. I purposely left out bonds for 2 reasons.
1. How much you should have allocated to bonds is very much personal situation dependent. I'm in my mid 30's and have 0%.
2. I think Bonds are a nightmare right now. Bonds have super low yields at the moment, and the US, UK and EU are all saying that in the medium to long term they will be raising interest rates (Bad for Bonds). Also as an Irish investor you'll be paying the 41% tax on any capital appreciation and/or Income tax on the dividends from any Irish/EU domiciled bond funds. You can use US domiciled Bond funds but these tend to be either US bonds or US$ hedged foreign bonds. The whole point of bonds is to reduce the risk of your portfolio. Holding US domiciled bonds introduces a large portion of currency risk for an Irish investor.
The ideal solution is an accumulating Euro based (or euro hedged) Bond fund. These do exist, but for the moment Irish investors still have to pay the 41% tax on them. IMO, this (along with the Med/Long term interest rate outlook) makes bond funds extremely unattractive.
At the moment, I use property funds (VNQ and VNQI) to diversify out my portfolio. They are not as good (in terms of diversification) as Bond funds would be, because they have approx. the same risk as stocks, however at least they are not particularly strongly correlated to stocks, so they do offer some diversification.
Annualized Arithmetic Return, Risk(Annualized Std Dev) , Correlation (to S&P500) , Sharpe Ratio
US Agg Bond : 7.58% , 5.38% , 0.21, 0.55
S&P 500 : 11.93% , 14.91% , 1.00, 0.49
Property REIT :14.51% , 16.94% , 0.57, 0.58
World stocks : 10.19% , 14.61% , 0.88, 0.38
London Gold : 7.34% , 19.33% , 0.01, 0.14