This volume highlights the latest advances, innovations, and applications in the field of stability of metal structures and composite materials structures, as presented by international researchers and engineers at the 9th International Conference on Coupled Instabilities in Metal Structures (CIMS), held in Timisoara, Romania, on September 21-23, 2026. It covers a diverse range of topics such as numerical simulation and FE computation, buckling, post-buckling and collapse of structures, cyclic and dynamic behaviour of structures, buckling of sandwich plates and shells, elasticity, plasticity, anisotropy and their effects on structural failure, sensitivity of structures to imperfections and residual stresses, behaviour of structures at elevated temperatures, fibre-reinforced thin-walled composite and hybrid structures, exploitation of buckling for structural applications, reliability and resilience of structural systems, design codes of practice and standards. The contributions, which were selected by means of a rigorous international peer-review process, present a wealth of exciting ideas that will open novel research directions.