The Johannesburg Stock Exchange (JSE) records its worst week in five months, the market's largest share Naspers sheds R121-billion, the rand falls to R15/$ for the second time in a week, global investors yank $1.3-billion out of emerging markets and nearly half of it from South Africa.

These headlines are enough to spook any investor. Compounded with disappointing returns from local investment markets over the past three years, many investors have or are considering switching investments, or out of shares or unit trust funds with higher exposures to shares and into safer cash investments like money market funds.

Usually, unit trust funds with exposure to share markets deliver more than money market funds. But over the past three years to the end of June, money market funds have returned around 7.4% a year, while the SA share market as measured by the All Share Shareholder Weighted Index returned just 5.7% a year.

But asset managers caution against switching to cash.

Old Mutual Investment Group points out that when you look at long-term trends, returns from money market investments have been 9% a year on average over the past 20 years to the end of last year, while the JSE delivered 15.2%.

Over 50 years, you would have earned 17.1% from shares on the JSE and 11% from money markets, Old Mutual's Long Term Perspectives shows.

Old Mutual's study of the markets dating back to 1927 also showed that there were many times like the past three years where shares delivered less than money markets - one third of all the three-year periods over the past 90 years.

But it's hard for us as ordinary investors to know when the returns will change and so it's best for us to wait out the periods of low returns in share markets.

Sherwin Govender, business development manager at Glacier by Sanlam, says it's natural to feel nervous about your investments at times like these.

"It becomes very difficult to be optimistic with the constant market shocks and negative news both locally and internationally," he says, adding that you must not let your fear lead you into making adverse decisions.

Nick Curtin, head of business development at Foord Asset Management, agrees that in this age of limitless, instantaneous information, it is increasingly difficult to focus on the things that really matter to long-term investment returns.

But history repeatedly shows us that markets recover from bad periods and that investors who ride out the tough times tend to do much better than those who sell out of the market, Govender says.

Your fund manager is the one who should be assessing the noise in the market to determine the most attractive investment opportunities and to manage the risks.

The most vital thing you can do is to stay invested through the inevitable market cycles, Curtin says. There is no starting point and no finish line for long-term savings, he says.

Govender says when you understand upfront what you are investing in, it is easier to tolerate the volatility.

If you are investing for a goal, like your retirement or for your children's education, and your investment term is five or more years away, you need to be exposed to shares and listed property to earn inflation-beating returns. This means you have to put up with volatility, but short-term market and currency movements shouldn't worry you.

A unit trust fund that invests in different assets classes - a multi-asset fund - may have more or less exposure to equities and listed property and higher or lower returns and volatility.

But when news is bad and markets are up and down, remember your longer term focus. Take a look at the graph of the All Share index since the beginning of this year - there are many ups and downs showing it's pretty volatile. Then take a look at the graph of the All Share index over the past five years.

There are ups and downs there too but overall the market is moving up, even if it has been a bit slower than usual over the past four years.