Bandwidth sensitivity test.

The construction of the Hainan Free Trade Port (HFTP) represents one of the most advanced regional development models explored by China. This study clarifies the concept of the free trade port and analyzes it from a trade perspective. Our empirical results show that the construction of the free trade port has significantly increased trade volumes, enhanced the diversification of products, and reduced the volatility of exports. A marked short-term surge in export volumes was observed immediately after the policy’s implementation. Moreover, the effects of the free trade port’s construction on trade are heterogeneous when viewed through the lens of product categorization.