A Market Forecast That Says ‘Take Cover’ WITH the stock market lurching again, plenty of investors are nervous, and some are downright bearish. Then there’s Robert Prechter, the market forecaster and social theorist, who is in another league entirely. Prechter is convinced that we have entered a market decline of staggering proportions — perhaps the biggest of the last 300 years. ...... Originating in the writings of Ralph Nelson Elliott, an obscure accountant who found repetitive patterns, or “fractals,” in the stock market of the 1930s and ’40s, the theory suggests that an epic downswing is under way, Mr. Prechter...