In order to answer this question, one should first understand the difference between risk and volatility.
Volatility refers to changes in the price of a stock on a market. We do not consider this a real risk for an investor. An analogy for market volatility might be that of turbulence experienced during a flight; while passing through turbulence can cause discomfort to passengers, it does not generally prevent an aeroplane from arriving at its destination. Investment risk is linked to the performance of the company itself rather than the volatility of its shares on the stock market. A company will experience a variety of risks irrespective of whether its share holdings are private or public (i.e. listed on a stock exchange). Understanding these risks is what matters to us.
We reduce risk by conducting detailed analyses of the companies in which we invest. We look for companies with a business model that is durable, a solid balance sheet and honest, competent management. Additionally, by buying stock that is undervalued we are protected against negative events that could affect our companies. The difference between the stock price and its value can be considered a margin of safety.
In summary, investing in stock markets will always involve a certain amount of risk, which can be minimized by using a value investing approach.