In recent years, US investment has been lackluster, despite rising valuations. Key explanations include growing rents … -- reflected in average Q -- and investment -- reflected in marginal q -- can be decomposed into three terms: the value of …

, collectively known as "intangible capital" can explain much of the weakness in physical capital investment since 2000. Moreover …

Capital investment decisions must recognize the limitations on the firm's ability later to sell off or expand capacity … to the q-theory of investment, and how these options affect the incentive to invest. Generally, the option to expand … effect of uncertainty on investment, how these option values change in response to shifts of the distribution of future …

This paper derives closed-form solutions for the investment and market value, under uncertainty, of competitive firms … irreversible investment as well as for reversible investment. Optimal investment is a non-decreasing function of q, the shadow … value of capital. The conditions of optimality imply that q cannot contain a bubble; thus, optimal investment depends only …

, scope, and investment decisions, and we outline their connection to recent macroeconomic and financial trends in the US …