Feenstra and Ma (2008) develop a monopolistic competition model where firms choose their optimal product scope by balancing the profits from a new variety against the costs of "cannibalizing" sales of existing varieties. While more productive firms always have a higher market share, there is no...

When employers face a trade-off between growing large and paying low wages - that is, when they have monopsony power - some productive employers will decide to acquire fewer customers, forgo sales, and remain small. These decisions have adverse consequences for aggregate labor productivity....