What is Risk?

Risk  is incorporated  into  so many  different disciplines from insurance to
engineering  to  portfolio  theory  that it should  come as no surprise that it is defined  in
different ways by each one. It is worth looking at some of the distinctions:

a. Risk versus Probability: While some definitions of risk focus only on the probability
of an  event occurring, more comprehensive definitions incorporate both  the
probability  of the event occurring and  the consequences of the event. Thus, the
probability  of a severe earthquake may  be very small but the consequences are so
catastrophic that it would be categorized as a high-risk event.

b. Risk versus Threat: In some disciplines, a contrast is drawn between risk and a threat.
A threat is a low probability  event with very  large negative consequences, where
analysts may be unable to assess the probability. A risk, on the other hand, is defined
to  be a higher probability  event, where there is enough  information  to  make
assessments of both the probability and the consequences.

c. All outcomes versus Negative outcomes: Some definitions of risk tend to focus only
on  the downside scenarios, whereas others are more expansive and  consider all
variability as risk. The engineering definition of risk is defined as the product of the                                               

probability of an event occurring, that is viewed as undesirable, and an assessment of
the expected harm from the event occurring.

Risk = Probability of an accident * Consequence in lost money/deaths

In contrast, risk in finance is defined in terms of variability of actual returns on an
investment around  an  expected return, even  when  those returns represent positive
outcomes.



Risk and Reward
The “no free lunch” mantra has a logical extension. Those who desire large
rewards have to be willing to expose themselves to considerable risk. The link between
risk and return is most visible when making investment choices; stocks are riskier than 
bonds, but generate higher returns over long  periods. It is less visible but just as
important when making career choices; a job in sales and trading at an investment bank

may be more lucrative than a corporate finance job at a corporation but it does come with
a greater likelihood that you will be laid off if you don’t produce results.

Not surprisingly, therefore, the decisions on how much risk to take and what type
of risks to take are critical to the success of a business. A business that decides to protect
itself against all risk is unlikely to generate much upside for its owners, but a business
that exposes itself to the wrong types of risk may be even worse off, though, since it is
more likely to be damaged than helped by the risk exposure. In short, the essence of good
management is making the right choices when it comes to dealing with different risks.






http://people.stern.nyu.edu/adamodar/pdfiles/valrisk/ch1.pdf