Supply Chain: Five freight indices diverge sharply on the magnitude of the China-to-US West Coast rate spike after the May 2025 tariff truce

Findings

• The SCFI recorded a 58% single-week jump in China-to-US West Coast spot rates after the May 12, 2025 tariff truce — the second-largest weekly point gain in SCFI history since 2009, exceeded only by the Red Sea crisis spike in late 2023. The SCFI captures headline spot rates on active sailings, representing the top of the market at the moment of measurement.
• Third-party indices measured the same week at 8–17%: Xeneta (which aggregates actual bookings across thousands of shippers) showed 8% in average spot rates and 18% at the 75th percentile; Drewry's WCI showed 10–17% for Shanghai-to-Los Angeles; Freightos FBX01 showed 13%. The Delta Engine returned INDETERMINATE (deltaFinal=1.286 vs. 0.05 threshold) — the largest spread observed in any Expanse run to date.
• The divergence is not a measurement error — it reflects what each index actually tracks. The SCFI captures the asking price for new spot contracts on current sailings; Xeneta and Freightos capture what shippers actually paid across the full booking market, including pre-negotiated rates. For a supply chain manager reading a headline about 'rates doubling,' the Xeneta 8% average is the more actionable number for budget planning; the SCFI 58% is the more actionable signal for spot procurement and capacity decisions.
• This structural divergence has direct consequences for any company ingesting multiple freight data feeds into a TMS, ERP, or cost analytics platform. A tariff event that generates a 58% signal in one index and an 8% signal in another will produce silently incorrect cost models and procurement alerts if the source mix is not monitored. UVRN's Delta Engine would flag exactly this discrepancy before it propagates downstream into incorrect freight accruals or misbid contracts.