Volatility is not risk. Risk is the reasoned probability of that investment causing it's owner a loss of purchasing power over his contemplated holding period.

Investing is often described as the process of laying out money now in the expectation of receiving more money in the future.

At Berkshire we take a more demanding approach, defining investing as

•  the transfer to others of purchasing power now with the reasoned expectation of receiving more purchasing power – after taxes have been paid on nominal gains – in the future. 
• More succinctly, investing is forgoing consumption now in order to have the ability to consume more at a later date.

From our definition there flows an important corollary: The riskiness of an investment is not measured by beta (a Wall Street term encompassing volatility and often used in measuring risk) but rather by the probability – the reasoned probability – of that investment causing its owner a loss of purchasing-power over his contemplated holding period. 

• Assets can fluctuate greatly in price and not be risky as long as they are reasonably certain to deliver increased purchasing power over their holding period. 
• And as we will see, a non-fluctuating asset can be laden with risk.

Investment possibilities are both many and varied.



http://www.berkshirehathaway.com/letters/2011ltr.pdf