Equity Bullwhip Effect

The bullwhip effect is a phenomenon in supply chains where a minor random fluctuation in downstream demand causes significant variability in orders placed by upstream suppliers. This amplification occurs due to compounding forecast errors across neighboring levels of the supply chain, resulting from imperfect information. When the random shock originates from the end retailer, the consequent volatility experienced by the end supplier increases substantially. In this paper, we propose a zero-capital hedged strategy to investigate the disparity in volatility between the end user and the end supplier. In the classic scenario of the bullwhip effect, we purchase shares of the end supplier while simultaneously short selling shares of the end retailer, which is the source of the shock. For the reverse bullwhip effect, the strategy is inverted. Utilizing only S&P 500 stocks, this combined strategy has yielded an annual long-short return of 20% with a Sharpe ratio of nearly 3. This study presents evidence of a stock Bullwhip effect for the first time.