Ensayos sobre la gestión financiera de los inventarios

Résumé

The purpose of this doctoral thesis is to deepen the behavior of inventory, a relevant item within the balance sheet of industrial companies. Previous finance literature has focused on the relation between inventories and the economic cycle. Inventory is often studied in operation management, but it is not frequent to find papers of the determinants of inventory. Besides, it is hard to find researches about company attributes that affect the speed of inventory adjustment. Finally, previous works have barely paid attention to the effects of inventory investment on profitability. All these aspects justify this doctoral thesis. The main objectives of this research are detailed below. Firstly, to study the determinants that affect the investment in inventory, such as internal and external finance, growth opportunities, tangibility and solvency and access to the capital market. Besides, to analyse the existence of an equilibrium level of inventory. The advantages and disadvantages related to a certain level of inventory generate a trade-off that justifies the interest in investigating the existence of an inventory equilibrium level. Secondly, to analyse the speed with which inventory reaches its equilibrium level from the current one. This speed depends on the adjustment cost of this process. Specific company attributes, such as financial restrictions or bargaining power, can explain the different behavior in the speed of adjustment towards the equilibrium level. Finally, to analyse the effects of inventory level over profitability, extending this analysis to every sector. The research makes use of samples of small and medium-sized companies in different periods, from 2008 to 2020. In order to control unobservable heterogeneity, panel data methodology has been applied. The partial adjustment model is proposed in the first two chapters. This model incorporates the determinants of the inventory plus the lagged dependent variable as explanatory variables, which makes it possible to explain the inventory adjustment process. The research confirms the existence of an equilibrium level of inventory to which the inventories converge. In addition, empirical evidence is provided on the determinants of inventory: age and external finance increase the level of inventory, whereas cash flow, tangibility, and growth opportunities reduce the level of inventory. Also, it is confirmed that certain company attributes affect the adjustment process towards the equilibrium level. Specifically, the speed of adjustment is reduced in those companies that suffer greater financial restrictions or have less bargaining power. Finally, it is verified that the accumulation of inventory affects the profitability of companies, being a negative linear relationship the one that underlies between both variables. The robustness checks confirm it. Also, the sectorial analysis confirms this behavior between profitability and inventory.