BOSTON - The stock market is in a groove. The Standard & Poor's 500 has climbed six months in a row and finished April at another record high. So far this year the index is up roughly 12 percent.
That sounds good, right?
A qualified "yes" might be the best answer. Consider that the past three years in a row, stocks began to tumble in May, and rallies turned into routs by midsummer.
That recent history doesn't necessarily suggest another market decline is around the corner, but some flash points that triggered the previous routs are still with us. The global economy can't seem to break out of its slow-growth mode. Europe's debt troubles have merely eased. The same can be said about U.S. fiscal policy gridlock.
This all means it's an opportune time to review the risk level in your portfolio. For starters, consider whether you've got 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'd have the fortitude to stay invested for an eventual recovery.
Another important step is checking the volatility of any mutual funds you own. There are a half-dozen or so commonly used tools to measure how much a fund's past performance varied from an index, or from peers investing in the same segment of the market.
The problem is there's no single measure that's universally considered the best for assessing risk. And average investors often end up frustrated at the complexity of the various tools.
Unless they take time to learn about the measures, their research may end up creating more confusion and uncertainty than actually placating them, says Cliff Caplan, a certified financial planner at Neponset Valley Financial Partners in Norwood, Mass.
Yet investors can benefit if they know how to use these tools. Here's a look at a few measures and their strengths and weaknesses:
Beta
Beta measures a mutual fund's risk level relative to the market over a given period, typically the past 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 might find a "low beta" fund appealing.
Beta is useful only if paired with other volatility measures. That's 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 whether the fund limited losses during market declines. How many investors complain about a fund that outperforms in a rally?
Standard deviation
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 past three-year period has been 15.01, and 18.8 over five years, according to Morningstar. Funds with figures below those numbers have been less volatile, and those above more volatile. Standard deviation is useful to help predict the range of returns to expect based on a fund's past results.
Sharpe ratio
This number is the product of a formula incorporating standard deviation. But it also factors in above- or below-market returns to show whether investors have been 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 has been relative to the risk taken.
Sortino ratio
This less widely known refinement of the Sharpe ratio is one of Mr. Caplan's favorites because it focuses on a fund's volatility when stocks fall. As a result, it measures a fund's success in limiting losses, unlike Sharpe, which also measures volatility when stocks rise.
Upside and downside capture ratios
These measures indicate what percentage of the market's gains or losses a fund was able to capture. For example, a fund might have moderately underperformed during rallies by matching 95 percent of the gains. But if that fund's losses were just 75 percent as steep as the market's declines, the fund probably outperformed the market over an extended period.
Such downside protection can be critical because of the realities of recovery math. If a fund loses 50 percent, it will need to subsequently post a 100 percent gain - not 50 percent - to get investors back to where they started.