Risky Suppliers or Risky Supply Chains? An Empirical Analysis of Sub-Tier Supply Network Structure on Firm Performance in the High-Tech Sector

Abstract

Past research in supply chain risk management has focused on the interactions between buyers and their immediate suppliers and/or assumed independence of risks imposed by these suppliers. However, supply network structure may induce inter-dependency of risks due, for example, to overlapping sub-tier suppliers. This paper empirically studies the prevalence of overlapping sub-tier suppliers and their impact on financial performance for firms in the high-tech sector. Using firm-level supplier-customer relationship data, we find that on average 20 (2.3) percent of tier-2 suppliers are shared by at least two (five) tier-1 suppliers. We also find that the risk, measured as stock return volatility, of the focal tier-0 firm is positively associated with common tier-2 supplier risk, and the association is stronger for suppliers with a higher degree of tier-2 commonality. To disentangle the impact of risky supply network structure from risky tier-2 suppliers, we define two network metrics, viz., diamond ratio and cosine commonality score. We find that a one standard deviation increase in each of these metric leads to an increase in standard deviation of 0.58 and 0.41 respectively in tier-0 firm's risk. Our results reveal substantial unmanaged supply chain risks due to overlapping sub-tier suppliers, and highlight the need for firms to increase visibility into their extended supply network.