Recent experiments on the kagome metal ${\mathrm{CsV}}_3{\mathrm{Sb}}_5$ reveal a curious phase transition-like feature: a nematic magnetic torque response that abruptly sets in at $T_{\tau }\simeq 130\mathrm{K}$, above the known charge-density wave (CDW) transition at $T_{\text{CDW}}\simeq 100\mathrm{K}$. Counterintuitively, elastoresistance measurements, a standard probe of nematicity, show no corresponding signal, ruling out a nematic phase transition and placing strong constraints on possible explanations. Beyond nematicity, the torque is paramagnetic for in-plane magnetic field, while above a critical out-of-plane field, an in-plane magnetization appears, accompanied by hysteresis. We show that this combination of features cannot be accounted for by charge-density waves or intraband magnetic order. Instead, we propose that interband ordering—via a symmetry-allowed interband spin-orbit coupling and a time-reversal and spatial symmetry-breaking interband order parameter—together with a background strain field, consistent with typical experimental conditions, provides a natural explanation; in our picture, the behavior at $T_{\tau }$ is understood as a crossover in the symmetry-allowed interband spin-orbit coupling strength. Our theory accounts for the nematic magnetic torque, hysteresis, and the transition-like onset at $T_{\tau }$, while also making testable predictions, including strain-induced magnetization. In doing so, it challenges the prevailing view of the normal state.

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• Excitonic insulators
• Spin-orbit coupling
• Van Hove singularity
• Kagome metal