We investigate if financial development (FD) can reduce the export concentration in regional context, corroborating the role of the World Trade Organization (WTO) membership, sanctions and investment potential. Given the considerable heterogeneity in data across regions and over time, we apply the Method of Moments Quantile Regression (MMQR) to analyze panel time-series data from 2009 to 2019. Our finding shows that bank credit disbursement as a proxy of FD drives export diversification in all quantiles (q10-q90), where the role of FD is pronounced at middle to higher quantiles. Besides, the impact of financial development on trade diversification is profound in the regions with higher business potential compared to the lower business potential. We affirm that the adaption of WTO membership elevates trade diversification through promoting competitiveness and providing nascent exporting sectors opportunities to grow. Surprisingly, the economic sanctions imposed in 2014 promoted Russian regional trade diversification. We provided several practical policy implications.