Grayscale Ethereum Classic Trust Adopts New NAV Index Effective Sept 1, 2026

What Happened
Grayscale Ethereum Classic Trust (ETC or the Trust) filed an 8-K (Aug 27, 2026) announcing that, effective September 1, 2026, the Trust will calculate its NAV and NAV per Share using the CoinDesk Ethereum Classic Benchmark Extended Rate (the “Index”). The Trust previously referenced the CoinDesk Ethereum Classic Price Index and will now use the CoinDesk Benchmark Extended Rate (the “Index Price”) for operational valuation of ETC holdings.

Key Details

• Effective date: September 1, 2026; NAV and NAV per Share will use the CoinDesk Ethereum Classic Benchmark Extended Rate.
• Index mechanics: the Index is USD‑denominated, calculated every 5 seconds over 24 hours, and uses volume weighting, FX conversion to USD, outlier detection, inactivity de‑weighting, and other manipulation‑resistance features.
• Valuation time: the Index Price used for Trust valuation is the Index value at 4:00 p.m., New York time, on each business day.
• Fallback pricing rules: if the Index is unavailable or deemed inaccurate, the Sponsor will first seek the Index Provider’s price, then use Coin Metrics Real‑Time Rate (secondary), the Trust’s principal market feed (tertiary), and finally the Sponsor’s good‑faith estimate as a last resort.
• Governance/changes: the Index Provider may change methodology, constituent venues, or weights (including monthly reviews) and can adjust calculations without notice; the Sponsor will notify shareholders of material changes.
• Coverage: the Index currently uses regulated spot trading venues (not OTC or derivatives) and applies inclusion criteria covering market quality, security, legal/regulatory status, KYC/AML, data quality, transparency, and governance.

Why It Matters
This change defines how the Trust values its ETC holdings for day‑to‑day NAV reporting. For investors, that means the Trust’s published NAV and NAV per Share will reflect the CoinDesk Benchmark Extended Rate and its calculation rules (volume weighting, outlier filters, 4:00 p.m. NY valuation). The filing also makes clear the Sponsor’s fallback pricing hierarchy and that the Index Provider can alter methodology or venue inclusion—factors that can affect NAV calculations during market disruptions or exchange incidents.