Grayscale Bitcoin Trust ETF 8-K

What Happened
Grayscale Investments Sponsors, LLC filed an 8‑K on March 16, 2026, announcing that the Grayscale Bitcoin Trust ETF (GBTC) will change the index used to value the Trust’s Bitcoin for operational purposes. Effective April 1, 2026, the Trust’s NAV and NAV per Share will be calculated using the CoinDesk Bitcoin Benchmark Rate instead of the CoinDesk Bitcoin Price Index (XBX). The filing describes the Benchmark Rate’s methodology and constituent trading platforms used to calculate the Index Price.

Key Details

• Effective date: April 1, 2026; filing date: March 16, 2026.
• Prior index: CoinDesk Bitcoin Price Index (XBX); New index: CoinDesk Bitcoin Benchmark Rate.
• Constituent trading platforms listed (as of March 16, 2026): Binance, Bitstamp by Robinhood, Bullish, Bybit, Crypto.com, Gate, Gemini, HashKey, Kraken, LMAX Digital, and OKX.
• Index calculation: algorithmic, volume‑weighted, recalculated every 5 seconds over a 24‑hour period; NAV uses the Index Price as of 4:00 p.m. New York time.
• Fallback pricing cascade if the Index is unavailable: (1) Index Price from CoinDesk; (2) Coin Metrics Real‑Time Rate; (3) the Trust’s principal market spot price; (4) Sponsor’s good‑faith estimate.
• The Index Provider may change methodology or constituent venues at its discretion under an existing license agreement; the Sponsor will notify shareholders of material changes in filings.

Why It Matters
This change affects how GBTC’s NAV and NAV per Share are calculated starting April 1, 2026. Different index methodologies or constituent venue sets can produce different reference prices for Bitcoin, which may affect reported NAV timing and valuation compared with prior periods. The filing also describes fallback rules and the Sponsor’s discretion in a disruption, so investors should note the effective date and the listed venues and understand that the Index Provider can adjust methodology without prior consent.