High-tech firms hold substantial cash reserves. We build a parsimonious industry equilibrium model with endogenous productivity to study high-tech firms' cash-saving policy and explore its role in innovation. The model incorporates multiple well-cited explanations in the literature and examines which factors are the main determinants of high-tech firms' saving behavior. We find that innovation uncertainty is the major driver, followed by knowledge spillover and financial frictions. Market competition has non-monotonic effects, while R&D adjustment costs play a relatively minor role. We also find that even if the productivity process is transitory, firms manage to save enough to reduce R&D distortions from financial frictions.

高科技公司持有大量现金储备。我们建立了具有内生生产率的简约行业均衡模型来研究高科技公司的现金储蓄政策并探索其在创新中的作用。该模型结合了文献中多个被广泛引用的解释，并检验了哪些因素是高科技公司储蓄行为的主要决定因素。我们发现创新的不确定性是主要驱动因素，其次是知识溢出和金融摩擦。市场竞争具有非单调效应，而研发调整成本的作用相对较小。我们还发现，即使生产力过程是短暂的，公司也设法储蓄足够的钱来减少财务摩擦造成的研发扭曲。