The literature on nexus between trade and business cycle synchronization have provided mixed and weak evidence of the effect of trade on business cycle synchronization as a result of lack of value-added bilateral trade data which provides solution for overestimation or underestimation of shock exposure when using gross trade data. Also, due to limited data on sectoral bilateral value-added trade, the literature has not been able to pinpoint the sectors where synchronization is necessary in order to economically direct all effort to these sectors in forging economic integration. The paper uses value-added trade data to examine the impact of trade on business cycle synchronization at the aggregate level and sector level and find a highly significant and highly positive effect of trade on the aggregate level. Estimates for agriculture, manufacturing, construction, total business, electricity gas and sewer, and other service sectors yield a positive significant effect in the service sector, indicating that attention should be focus on the service and business sector when integrating economically. In this paper we examine output cycle synchronization patterns of the countries that joined the Eurozone later and countries that are in preparation or committed to join in relation to the original Eurozone members. We analysis this in the contest of before, during and recovery periods of the global financial crisis investigate the differences in the patterns of synchronization for late and future members of the Eurozone. For more understanding, we examine the pattern on disaggregate level using data for agricultural, manufacturing, construction, utility, total business and other services sectors from 1995-2015. Also, we examine the importance of trade on output synchronization both on the aggregate and disaggregate level using System GMM which not only solves the problem of endogeneity, but it estimates the persistence of business cycle synchronization efficiently. The result provides evidence of a positive persistence; however, synchronization pattern differs between late and future member states. Also, the financial crisis had a negative effect on synchronization in the European sub region as result the difference in the response by member states. The result shows a weak evidence of the importance of trade as a channel of synchronization. Even though previous studies have provided evidence improvement in UK and the Eurozone output comovement, Brexit came to pass. This has questioned the potency of the Enlargement of the Eurozone Initiative. This paper reexamines the degree of business cycle synchronization between the Euro area countries and United Kingdom in attempt to find an economic reason for Brexit. We also examine if the disaggregate economy have share similar pattern as the aggregated economy using the output synchronization in the agricultural, manufacturing, constructions, utility, total business and other service sectors between the euro area countries and United Kingdom. Using valued-added trade data between 1995 and 2015 from WTO-TiVA database we further examine effect of trade (sectoral trade) on the output (sectoral output) synchronization. Furthermore, we analyze the same questions in the contest of before and after the global financial crisis. The result show that the UK-EMU trade channel is no important to the output cycles synchronization. Also, due the unstable pattern or persistence of UK-EMU synchronization the EMU will have little effect from the Brexit if there exit one.