Ever since the stocks plummeted in early August, the stockmarkets have been all over the place. One day they shoot up only to tumble down the next day. And so on for nearly two months. As you put it, financial markets are displaying a split personality (“Mood Swings,” October 1, 2011). I would rather call it a bipolar disorder, which is also known as a manic-depressive disorder. It is characterized by the presence of repeated episodes of abnormally elevated energy levels, cognition, and mood interspersed with depressive episodes. Severe manic episodes can on occasion lead to psychotic symptoms, such as delusions and hallucinations. Today’s stockmarkets in a nutshell. Among the reasons for such behavior you list quite a few, starting with the stalling growth in the rich world and the ever-deeper crisis of the euro. But there is one palpable reason you eschew entirely: the growing signs of another global depression. Every whiff of it leads to mood depression, and every ray of hope leads to manic behavior, including hallucinations. The stockmarket bipolar disorder can tell us a good deal about the trouble ahead.