Marchenko-Pastur (1967):
ρ(λ) = √[(λ₊-λ)(λ-λ₋)] / (2πγλ)
where λ± = (1 ± √γ)²
For γ < 1: eigenvalue support is a single arc. For γ ≥ 1: a point mass at 0 with weight 1−1/γ appears.
Tracy-Widom: largest eigenvalue fluctuates as n^(−2/3) with TW₁/TW₂ distributions.