A new paradigm: the wealth effect of the stock market on consumption,in a context of interacting bio-systems

This study examines the existence of a stock market wealth effect on aggregate private consumption in the economy. A theory of investor/consumer behavior is suggested, in a context of a symbiotic relationship between two quasi-bio-systems. The model offers predictions about likely outcomes in capital market interaction with the underlying economy in general and consumption in particular. These predictions are validated empirically. Specifically, the paper finds that investors/consumers do not respond immediately to a stock market rise (fall). Rather, they wait at first and thereafter gradually accelerate their ‘wealth spending’ on consumption only after they are convinced that the gain is permanent (a variation of the ‘income smoothing’ that was suggested many years ago by Friedman (1957)). The paper suggests that the capital markets and the economy interact like two bio-systems symbiotically responding to each other. This study presents evidence that the consumption wealth spending peaks at approximately 2.5% of the stock market wealth CUMULATIVE gain in the previous 12–24-month period, with some effects lingering on up to 36 months. For example, it shows that over 40% of the growth in consumer spending in 1999 was attributable to gains in the stock market in previous years, contributing to a strong GDP in that year.