The stock market is in a groove. The Standard & Poor's 500 has climbed six months in a row and finished the week at a record high. Sounds good, right?

A qualified "yes" may be the best answer, considering that in the last three years, stocks began to tumble in May, and rallies turned to routs by midsummer.

Recent history doesn't necessarily suggest another market decline, but some flash points that triggered the previous routs are still with us. The global economy can't seem to break out of slow-growth mode. Europe's debt troubles have merely eased. The same can be said about U.S. fiscal-policy gridlock.

Which makes this an opportune time to review the risk level in your portfolio. Consider whether you have an appropriate mix of stocks, bonds, and other investments to meet your savings goals. Then examine the potential consequences for your immediate and long-term finances if stock prices tumble, and whether you would have the fortitude to stay invested for an eventual recovery.

Another important step: checking the volatility of the mutual funds you own. There are tools to measure how much a fund's performance varied from an index, or from peers investing in the same market segment.

The problem is there's no single measure universally considered the best for assessing risk. And investors often end up frustrated at the tools' complexity. Unless they take time to learn about the measures, their research may end up creating more confusion, said Cliff Caplan, a certified financial planner at Neponset Valley Financial Partners in Norwood, Mass.

Few investors are interested in discussing statistical measures, Caplan said: "They just want to know that I'm taking measures to mitigate risk."

Yet investors can benefit if they know how to use these tools. Here is a look at some of them:

Beta measures assess a mutual fund's risk level relative to the market over a given period, typically the last three years, as with most fund-volatility measures. A fund with a beta of 1.0 has generated returns that are as volatile as the market. A beta of 0.80, for example, means the fund is less volatile - it gained or lost 8 percent during a period when the market moved 10 percent. A risk-averse investor may find a "low beta" fund appealing.

Beta is useful only if paired with other volatility measures because it doesn't indicate if stock prices were rising or falling when the fund's performance was deemed less volatile. The critical factor is if the fund limited losses during market declines.

Standard deviation is a measure of how widely a fund's returns have varied compared with the market. For example, the standard deviation of the S&P 500 over the last three years has been 15.01, according to Morningstar. Funds with figures below that were less volatile, those above were more volatile.

Sharpe ratio is the product of a formula incorporating standard deviation. But it also factors in above- or below-market returns to show whether investors were rewarded for the level of risk taken. A Sharpe ratio is often close to 1.0, say 0.9 or 1.1. The higher the number, the stronger the fund's performance relative to risk taken.

Sortino ratio focuses on a fund's volatility when stocks fall, and measures a fund's success in limiting losses, unlike Sharpe, which also measures volatility when stocks rise.