موجودی انبار، ساختار مالی و ساختار بازار

In this paper, we study the effect of different financial contracts on the firm's inventory policy. Doing so will allow to define the best financial instruments to diminish the stock variability of a profit-maximizing firm in a given economic environment (expansion or recession), and for a given market structure. We show that in periods of recession (expansion), reducing (increasing) the amount of short-term debt is an optimal strategy independently of the market structure.

This paper studies the impact of product differentiation and financial structure on firms’ inventory policy. This type of analysis is supposed to deliver a global perspective on the interaction between input and output markets, and the dynamics of firms’ inventories. We believe that this is a relevant question insofar the variability of firms’ stocks is recognized to be one of the driving forces of business cycle fluctuations. In order to give a broad idea of this phenomenon, Blinder and Maccini [1] find that up to 87% of GDP variance during short-term (ST henceforth) recessions is linked with drastic inventory reductions.1 Other sources2 find that as much as 11% of Chinese GDP is stored in stocks. From these pieces of evidence we can understand the rationale for a Central Authority to give incentives to profit-maximizing firms for smoothing their steep inventory disinvestment (investment) in recessions (expansions). Hendel [2] links this issue with firms liquidity needs in the ST. Firms tend to increase their cash reserves through an aggressive stock disinvestment in order to satisfy ST financial obligations. In this perspective, it is an issue of interest to study the firms’ interaction between inventory policy and their financial structure. Other studies such as Carpenter et al. [3], Kashyap et al. [4] and Olney [5] find a stronger impact of cyclical fluctuations on small firms’ inventory variability than on that of bigger firms. These authors link this result to the fact that smaller firms can only obtain external funds through credits with ST maturities. On the other hand, larger firms can also obtain long-term (LT henceforth) financing (LT debt or equity). Here we propose a model in which firms are hit by both economy-wide supply-side and economy-wide demand-side shocks. Focusing on economy-wide shocks allows us to avoid aggregation issues among different markets subject to idiosyncratic shocks. Furthermore, economy-wide shocks are those which trigger expansions or recessions. In our setup, firms compete in a monopolistic competitive market, designing their inventory policy as a profit maximizing function of their financial structure, the shocks, and the market structure. We consider different financial contracts that link firms with their fund providers. This allows us to study the effect of different financial instruments (debt or equity) with different lenders (banks or market) on a profit-maximizing firm's stock policy under alternative market structures. Such an analysis has normative implications for a Central Authority that would affect firms’ financial structure as a way to smooth inventory fluctuations and ultimately, cyclical fluctuations. Four main results are obtained in our model. First, the impact of product market differentiation on inventory investment is such that, in expansions, the inventory variance increases as markets become more fragmented, and vice versa in recessions. Second, regarding the role of firms financial structure, we prove that market debt-financed firms store a lower inventory level than bank debt-financed firms, which in turn accumulate less than equity-financed firms. Third, the higher (lower) the amount of ST debt in expansions (recessions), the lower stock fluctuations in expansions (recessions) for a profit-maximizing firm. This in turn implies that firms using variable-rate credit define a smoother inventory policy than firms using fixed-rate credits. Finally, we describe a possible mechanism that would provide profit-maximizing firms with cheap financing and at the same time smooth their inventory accumulation policy. The paper is organized as follows. Section 2 sketches our basic model. In Section 3 we solve the model and present our main findings. Section 4 concludes.

We have studied firm inventory policy in an environment with supply and demand shocks, taking into consideration different product market structures as well as firm financial structures. We have shown that in an expansive (recessive) period, inventory variance increases (decreases) as markets become more fragmented. Concerning firm financial structure, we have found that market debt-financed firms store a lower level of inventories than bank debt-financed firms, which in turn accumulate less than equity-financed firms. This particular ranking can be explained in terms of liquidity considerations. Equity-financed firms do not have liquidity obligations to be satisfied and, during expansions, can invest freely in illiquid assets such as stocks. This is not the case for debt-financed firms, especially if debt is short term. These firms need to keep a substantial amount of resources in cash, in order to satisfy their monetary obligations and avoid liquidation. This fact discourages them from implementing an aggressive policy of stock accumulation during expansions and, by the same token, leads to a strong inventory disinvestment in recessions. Such liquidity effect is particularly important for market debt-financed firms, as they cannot use inventories as a means of payment. As a consequence, the higher (lower) the amount of ST debt in expansions (recessions), the lower stock fluctuations in expansions (recessions) for a profit-maximizing firm. This in turn implies that firms using ST variable-rate credit (more cash demanding in expansions than in recessions) will define a smoother inventory policy than those using fixed-rate credit. On the basis of the previous analysis, we could describe a mechanism that stimulates profit-maximizing firms to smooth their inventory policy while obtaining “cheap” financing. This consists of raising funds in a recessive period, making use of LT convertible debt. These bonds would incorporate two ex-ante conditions: first, they must be transformed in equity in the next expansive period, and second, there must be a firm commitment to buy back a certain proportion of this equity. The buy-back commitment will make this instrument attractive to potential lenders, providing firms “cheap” liquidity in recessive periods and avoiding an inventory overselling. At the same time, the use of available resources in expansions for the purchase of equities committed ex-ante will prevent a substantial investment in non liquid assets such as inventories. As a final remark, an interesting extension to this model would contemplate issues of aggregation of firms’ inventory policies across markets subject to idiosyncratic shocks. This would provide an insightful alternative to the case of common shocks analyzed in this paper. Such an extension is left for future research.