Submitted by Rafael Ornelas (rafael.amaral.ornelas@gmail.com) on 2014-10-13T14:42:40Z No. of bitstreams: 1 Comparative Advantage, Heterogeneous Firms and Variable Mark-ups.pdf: 719604 bytes, checksum: a740a6997be4cfdd2be9d1a7f48aad00 (MD5) / Approved for entry into archive by BRUNA BARROS (bruna.barros@fgv.br) on 2014-10-13T17:17:33Z (GMT) No. of bitstreams: 1 Comparative Advantage, Heterogeneous Firms and Variable Mark-ups.pdf: 719604 bytes, checksum: a740a6997be4cfdd2be9d1a7f48aad00 (MD5) / Approved for entry into archive by Marcia Bacha (marcia.bacha@fgv.br) on 2014-10-14T11:58:54Z (GMT) No. of bitstreams: 1 Comparative Advantage, Heterogeneous Firms and Variable Mark-ups.pdf: 719604 bytes, checksum: a740a6997be4cfdd2be9d1a7f48aad00 (MD5) / Made available in DSpace on 2014-10-14T11:59:35Z (GMT). No. of bitstreams: 1 Comparative Advantage, Heterogeneous Firms and Variable Mark-ups.pdf: 719604 bytes, checksum: a740a6997be4cfdd2be9d1a7f48aad00 (MD5) Previous issue date: 2014-06-27 / We develop a model of comparative advantage with monopolistic competition, that incorporates heterogeneous firms and endogenous mark-ups. We analyse how these features vary across countries with different factor endowments, and across markets of different size. In this model we can obtain trade gains via two channels. First, when we open the economy, most productive firms start to export their product, then, they demand more producing factors and wages rises, thus, those firms that are less productive will be forced to stop to produce. Second channel is via endogenous mark-ups, when we open the economy, the competition gets ``tougher'', then, mark-ups falls, thus, those firms that are less productive will stop to produce. We also show that comparative advantage works as a ``third channel'' of trade gains, because, all trade gains results are magnified in comparative advantage industry of both countries. We also make a numerical exercise to see how endogenous variables of the model vary when trade costs fall.