  The decay $B_d \to \phi K_S$ is a special probe of physics beyond the
Standard Model (SM), since it has no SM tree level contribution. Motivated by
recent data suggesting a deviation from the SM for its time-dependent CP
asymmetry, we examine supersymmetric explanations. Chirality preserving
contributions are generically small, unless gluino is relatively light. Higgs
contributions are also too small to explain a large asymmetry. Chirality
flipping $LR$ and $RL$ gluino contributions actually can provide sizable
effects without conflict with all related results. We discuss how various
insertions can be distinguished, and argue the needed sizes of mass insertions
are reasonable.
