In every tumultuous market, investors seek out a guru who can divine a market turn. This time, investors are finding comfort in Mr. Nenner, who runs Cycle Forecasting Inc. Mr. Nenner is about as unconventional as they come. He lives in Jerusalem, spends much of his day studying the Talmud, and sends twice-weekly emails predicting moves in everything from U.S. and European stocks to oil and cattle prices.Mr. Nenner sent a prescient email predicting that the U.S., Japanese and European stock markets would hit a high on May 10.

That day, markets around the globe hit a peak. Since then, the Standard & Poor's 500-stock index has dropped 5.5% and global markets have fallen further. In late May, Mr. Nenner said the S&P and Nasdaq Composite Index "should now turn down again into 6/14" -- a reference to June 14. That too was an on-the-money call; June 14 was the recent low for the stock market. Now, Mr. Nenner expects stocks to stay strong until July 10 but foresees another weak patch after that.