But doing that inevitably brings the risk back into what was a risk-free investment.

It's also the case that US debt remains the benchmark for risk-free investment, and if that changes, it'll have ripple effects across the world.

And because they only pay off if the stock rises, companies like to think of them as risk-free investments.

But let the buyer beware: franchises, even involving established, successful companies, are not risk-free investments.

Morningstar looks at a fund's monthly returns and how many times it has failed to match the results of risk-free investments like Treasury bills.

Somewhere there's a more risk-free investment.

Reports of rising unemployment and the Fed's quick response last week left many risk-free investments paying too little even to keep up with 3.5 percent inflation.

Investors who buy and later sell in the first day's trading often have a risk-free investment.

Figure 5 shows that an investor will choose a portfolio on the efficient frontier, in the absence of risk-free investments.

And what if he suddenly sold all of his shares and bought 30-year Treasury bonds, a risk-free investment?