Inventory Signals

Among practitioners, inventory is often thought to be the root of all evil in operations management. The stock market hates it, the media abhors it, and managers have come to fear it. But high inventory levels can also be the result of strategic buying and high-availability strategies. The problem is that when the market sees lots of inventory, it cannot tell whether it is because of poor or smart operations. We hypothesize that inventory has a signaling role. In our model, publicly- traded firms use inventory levels to signal their operational competence to the market. There is a separating equilibrium that leads some firms to maintain inventory levels below what their capability could achieve. We offer this as one explanation why, for example, stock-outs are pervasive even among operationally competent firms. We provide empirical evidence for the assumptions behind this inventory signaling hypothesis: (1) the market cannot tell the difference between “good” and “bad” inventory; and (2) the counterfactual: the market punishes firms when it can tell that their inventory is bad, such as when they write off supplies. Consistent with these assumptions, we find that inventory levels do not explain firm value. And on average, stocks suffer an abnormal negative return of 7% in the month of announcing inventory write-offs.