Bonds will be the least risky since there is no risk involved at all. Bonds give out guaranteed payments and A rated bonds will be even more secure.
The next would be property. Since property is a physical asset, the risk involved is relatively lower than stocks.
The next would be retirement plans which would typically have bonds and stocks.
The most risky would be speculative stocks.
The order from least risky to most risky would be:
1. A rated bonds
2. Property
3. Retirement plans
4. Speculative stocks
