{"generated_at": "2026-05-21T17:14:50+00:00", "underlying": "SPY", "spot": 741.25, "vix": 16, "regime": "market_closed", "interpretation": "Options market closed (weekend / holiday / outside regular hours). GEX cannot be computed live; last valid reading preserved.", "market_closed": true, "last_valid_at": "2026-05-21T16:44:50+00:00", "last_valid_total_gex": null, "last_valid_regime": "market_closed", "fetch_duration_s": 0.4}