Inventory Levels of KOSPI-Listed Manufacturing Firms Between 2000 and 2019

Purpose This study investigates whether the inventory levels of Korean manufacturing firms increased or decreased from 2000 to 2019. We also explore the relationship between inventory levels and firm performance. Design/methodology/approach We use panel data on KOSPI-listed firms in the manufacturing industry. We measure days in inventory as a proxy for inventory levels, and firm performance is measured by return on assets, return on sales, and EBITDA ratio. The panel data regression method is employed in our analysis. Findings We find that days in inventory of Korean manufacturing firms significantly increased from 2000 to 2019, especially for raw materials and finished goods inventory. In addition, while days in inventory of large- and medium-sized firms were less than those of small-sized firms, the change in days in inventory of large- and medium-sized firms was positively significant over time. Moreover, the increase in days in inventory was more prevalent among industries related to foods, clothes, chemicals, and transportation. Finally, we show that the days in inventory are negatively related to firm performance. Research implications or Originality While the Korean manufacturing industry has enormously grown over the last 20 years and managing inventory is critical in the manufacturing industry, our findings counter-intuitively show that the days in inventory of the Korean manufacturing industry had been gradually increased. We speculate that the increase in days in inventory is due to the Korean manufacturing firms’ heavy reliance on global supply chains.