Sidney B. Wachtel

Sidney B. Wachtel, 90, an economist, investment banker and founder of Wachtel & Co., a Washington-based investment and brokerage firm, died Sept. 26 of cardiac arrest at his home in Washington. Mr. Wachtel studied seasonal movements in the stock market and coined the investment term “the January effect,” the theory that American stock prices rise more in January than any other month. This idea was expanded on in his 1942 paper, “Certain Observations on Seasonal Movements in Stock Prices,” which appeared in the Journal of Business published by the University of Chicago Press.From 1948 to 1959, he worked as an international financial economist for the Treasury Department. He operated investment clubs in Northern Virginia before starting Wachtel & Co. in 1961 with his wife, Irma Schocken. Wachtel & Co., which is operated today by Mr. Wachtel’s two daughters, acts as an investment banker and financial adviser to small emerging companies. Mr. Wachtel helped finance local companies such as Radiation Systems, Waxie Maxie Music Stores and Data Measurement Corp. “Our business is very risky,” Mr. Wachtel told The Washington Post in 1980. “We don’t get paid off for years. Most of the time, there is no payoff. But when there is a payoff, it’s a big one.” Sidney Barnett Wachtel was born in New York City. He studied economics and statistics, receiving a bachelor’s degree in 1939 and a master’s degree in 1941, both from New York University. His 32 year marriage to Schoken ended in divorce in 1980. She died in 2007. Survivors include his companion of more than 10 years, Susan Maloney of Washington, and two daughters from his marriage, Wendie and Bonnie Wachtel, both of Washington.