Abstract: Based on financing constraints, in this paper, the investment timing and financing scale of small and medium-sized enterprises are investigated. Besides, the closed-form prices of corporate bonds, equity, company value, and the guarantee cost are derived by using the risk neutral pricing approach. In addition, the functional relationship between investment and debt scale is determined and the advantages of the swap are explained. The numerical analysis shows that the investment trigger decreases first and then increases with the financing scale, where there is a U-shaped relationship between them. The company value with guarantee is greater than that of equity financing. But with the increase in risk, the difference between the two values becomes smaller. The comparative static analysis also indicates that the company value is increased and the investment is accelerated.

Key words: small and medium-sized enterprises, investment timing, debt scale

摘要： 研究了融资约束模式下的中小企业投资时机和融资规模。利用风险中性定价方法给出了公司债券、股权、公司价值和担保成本定价的显式解；确定了投资时机与债务规模的函数关系；解释了担保换股权融资模式的优势。数值分析结果表明：投资触发水平随融资规模先减后增呈U型变化；被担保的公司价值大于股权融资的公司价值。随着风险的增大，两价值之差越来越小。比较静态分析也表明，担保换股权使得公司价值增加，投资被加速。

关键词: 中小企业, 投资时机, 债务规模