We show that a trade model with an exogenous set of heterogeneous firms with fixed operating costs has the same aggregate outcomes as a span-of-control model. Fixed costs in the heterogeneous-firm model are entrepreneurs' forgone wage in the span-of-control model.
Published in: _Economics Letters_ (Vol. 146, 2016, pp. 01-03) https://doi.org/10.1016/j.econlet.2016.07.012.