This paper extends the Q-theory of investment to capital goods with arbitrary efficiency profiles. Under the assumption of geometric economic depreciation employed by the traditional Q-theory, a firm's replacement cost of assets-in-place is independent of their vintage composition and can be...

We take a simple q-theory model and ask how well it can explain external financing anomalies, both qualitatively and quantitatively. Our central insight is that optimal investment is an important driving force of these anomalies. The model simultaneously reproduces procyclical equity issuance...