Recent disruptions at major maritime chokepoints have exposed the structural fragility of liner shipping networks. Existing indicators measure connectivity, but none quantify its structural vulnerability from a supply-side perspective. We propose the Maritime Connectivity Vulnerability Index (MCVI), capturing three dimensions mapped to distinct UNCTAD sources: low overall connectivity (LSCI), weak bilateral integration (LSBCI), and port infrastructure concentration (PLSCI). The index covers 185 economies over 2006-2025 using pooled fractional rank normalization and equal-weight aggregation from publicly available data. SIDS exhibit a mean vulnerability 0.234 points above non-SIDS economies, with the gap widening from 0.232 to 0.249 over two decades. A modest global decline of 4.2% is observed. Port concentration dominates for nearly 40% of economies (72 of 185), establishing infrastructure diversification as a distinct policy priority. Rankings are highly stable across alternative weighting schemes, normalization methods (Spearman rho = 0.97-0.999), and PCA-derived weights; Monte Carlo simulation (1,000 replications) confirms rho > 0.95 in every realization. External validation shows strong negative correlation with the World Bank Logistics Performance Index (rho = -0.61 across seven waves) and positive correlation with ad valorem maritime freight rates (rho = +0.32). Panel regressions reveal a vulnerability paradox whereby small trade-dependent economies are simultaneously the most trade-open and the most vulnerable. Pre-crisis MCVI predicts trade losses during the COVID-19 supply shock (rho = -0.25, p < 0.005), while the contrasting positive correlation during the 2008-2009 demand shock (rho = +0.23, p = 0.01) validates the supply-side specificity of the index.

翻译：近期全球主要海上咽喉点的中断事件暴露了班轮运输网络的结构性脆弱性。现有指标虽能衡量连通性，但均未从供给方视角量化其结构性脆弱性。本文提出海上连通脆弱性指数（MCVI），从三个维度（映射至联合国贸发会议不同数据源）进行刻画：低水平整体连通性（LSCI）、薄弱双边整合程度（LSBCI）及港口基础设施集中度（PLSCI）。基于2006-2025年185个经济体的公开数据，采用合并分位数排名标准化与等权重聚合方法构建该指数。结果显示：小岛屿发展中国家的平均脆弱性比非小岛屿发展中国家高出0.234个点，且该差距在二十年间从0.232扩大至0.249；全球脆弱性整体小幅下降4.2%。港口集中度主导了约40%经济体（185个中的72个）的脆弱性，表明基础设施多元化应成为独立政策优先事项。在替代赋权方案、标准化方法（斯皮尔曼相关系数=0.97-0.999）及主成分分析衍生权重下，排名高度稳定；蒙特卡洛模拟（1000次重复）证实每次实现中相关系数均>0.95。外部验证显示，该指数与世界银行物流绩效指数呈强负相关（七轮调查相关系数=-0.61），与从价海运运费率呈正相关（相关系数=+0.32）。面板回归揭示"脆弱性悖论"：贸易依赖型小经济体同时呈现最高贸易开放度与最大脆弱性。危机前MCVI可预测新冠肺炎疫情期间供给冲击造成的贸易损失（相关系数=-0.25，p<0.005），而2008-2009年需求冲击期间呈现的对比性正相关（相关系数=+0.23，p=0.01）则验证了该指数的供给方特异性。