The money world abounds with risks, as the past year  has vividly illustrated. And financial jargon has a name for most of them. There is, for example, “credit risk,” or the chance that a debtor won’t repay. Or “interest-rate risk,” the danger that interest rates will rise, causing investments like bonds to lose value. Or “currency risk,” when the value of an investment declines because of a change in the underlying currency. Just recently, via this article in a trade magazine for financial planners, we read about a new one: “media risk,” or the possibility of making a dumb move by overreacting to the financial news. Not that any of us would ever do anything like that, of course...