The number of people performing low-skill, low-pay, manual labor tasks has grown along with the number undertaking high-skill, high-pay, nonroutine, principally problem-solving jobs.

Market prices are often driven by choices later viewed as mistakes. Waves of optimism or pessimism sometimes dramatically move prices; a burst bubble of euphoria can bring significant macroeconomic consequences. ; A sudden change of sentiment may occur when a large number of stock market...