Standard finance theory suggests that managers invest in projects that, in expectation, produce returns that justify the use of capital. An underlying assumption is that managers have the information necessary to understand the distributional properties of the pay-offs underlying the decision. This paper examines firm investment behavior when managers are likely to find it more challenging to develop expectations of pay-offs, namely during periods of increased macroeconomic ambiguity. In particular, we examine how macroeconomic ambiguity – proxied by the variance premium (Drechsler, 2010) and the dispersion in forecasts of corporate profits from the Survey of Professional Forecasters (Anderson et al., 2009) – impacts managerial capital inve...