In this paper, we combine a matching model derived from Pissarides (2000) in the case of large firms with monopolistic competition on the product market and the model of intrafirm bargaining à la Stole and Zwiebel (1996). Moreover, we allow for increasing returns to scale in the aggregate production function leading to multiple equilibria. Then, we study the dynamics of such a framework for various size of returns to scale and propose numerical simulations. Finally, we show how the dynamical properties are altered in the case of multiple equilibria compared to that of a unique equilibrium and illustrate the issues of economic policy design in presence of multiple equilibria.