Recent studies have found unmeasured intangible capital to be large and important. In this paper we observe that by nature intangible capital is also very different from physical capital. We find it plausible to argue that the accumulation process for intangible capital differs significantly from the process by which physical capital accumulates. We study the implications of this hypothesis for rational firm valuation and asset pricing using a two-sector general equilibrium model. Our main finding is that the properties of firm valuation and stock prices are very dependent on the assumed accumulation process for intangible capital. If one entertains the possibility that intangible investments translates into capital stochastically, we find that plausible levels of macroeconomic volatility are compatible with highly variable corporate valuations, P/E ratios and stock returns.