The impact that output has on future total factor productivity is not internalized by competitive agents. As a result, the allocation that a planner would choose cannot be reached as a competitive equilibrium outcome (neither for infinitely lived agents nor for overlapping generations): the market remuneration to capital and labor is too low. The planner's allocation can nonetheless be implemented by a fiscal policy subsidizing the returns to savings and the wage rate as needed. The exact policy differs depending on whether only past investment or total output influences productivity: in the first case only capital returns need to be subsidized, whereas in the second case labor income needs to be subsidized too. The policy is balanced period by period by means of a lump-sum tax.

When the production function includes dynamic complementarities and a Cobb--Douglas form, dynamic complementarities are an endogenous propagation mechanism of shocks. The proposed model explains several stylized facts of aggregate variables of interest, including (i) hump-shaped impulse response functions, (ii) positively autocorrelated growth rates of aggregate variables, and (iii) correlation coefficients of forecastable movements in aggregate variables.