We demonstrate that demand uncertainty can explain equilibrium product variety in the presence of sunk costs. Product variety is an efficient response to uncertainty because it reduces the expected costs associated with excess capacity. We find that within the firm's product line, the highest...

In this paper, we assess the cyclicality of mark-ups and profit margins within the United Kingdom, at both the aggregate and industry level. We find that the private sector labour share moves countercyclically, suggesting that the aggregate mark-up moves procyclically. This result survives when...