Left panel: distribution of the (normalised) eigenvalues λ_i of the potential energy overdensity tensor. Filled and open histograms show results for all sampled protohaloes having masses larger than 4 × 10¹⁴h⁻¹ M_⊙ (from Flora) and larger than 10¹¹ h⁻¹ M_⊙ (from Bice), respectively. Right panel: same, but now for the eigenvalues ${\overline{\lambda }}_i$ of the traceless part of the potential energy overdensity tensor. Filled and open histograms are very similar, indicating that differences in the left panel are mainly driven by the mass-dependence of the trace.