Heads, shoulders and broadening bottoms

THE popularity of business television channels such as CNBC has done wonders for the careers of Wall Street's technical analysts, who claim to be able to predict future share prices by spotting trends in past prices. Their market charts, showing descriptively named patterns such as “head and shoulders”—a big peak surrounded by two smaller peaks—or “broadening bottoms”—a series of troughs, each lower than the preceding one—make ideal graphics for television producers in need of something pretty for viewers to watch while the glamorous reporters are busy off-camera, catching up on the latest market gossip. The simple trading advice conveyed by charts is, for CNBC's stock-tip-hungry viewers, manna from heaven.