Deep Selective State-Space Models (SSMs) with discontinuous gating signals pose challenges for stability analysis.The stability and regularity properties of continuous-time selective SSMs are investigated using passivity and Input-to-State Stability (ISS).Intrinsic energy dissipation in selective SSMs ensures exponential forgetting of past states.The research establishes conditions for global ISS, linking local dissipativity to overall system robustness for deep selective SSMs.