Grayscale Sui Staking ETF Adds Anchorage Digital as Additional Custodian

On September 29, 2026, Grayscale Investments Sponsors, LLC, the sponsor of the Grayscale Sui Staking ETF (ticker: GSUI), entered into the Sixth Amendment to the Master Custody Service Agreement with Anchorage Digital Bank N.A. This agreement designates Anchorage Digital as an additional custodian for the Trust.

Under the terms of the new agreement, Anchorage Digital will provide custody and safekeeping services for a portion of the Trust’s SUI holdings. The Sponsor intends to utilize these services to custody a portion of the Trust’s SUI. The Trust’s existing custody arrangement with Coinbase Custody Trust Company, LLC remains in place, and Coinbase continues to serve as the Trust’s primary custodian.

The Sponsor retains discretion to determine the specific amounts of SUI held at either custodian. As of the filing date, the Sponsor has not determined the total amount of SUI to be moved to Anchorage Digital. The addition of Anchorage Digital is described as a reflection of the Sponsor’s ongoing risk management approach as the Trust’s assets grow.

Regarding operations, upon Sponsor instruction, Anchorage Digital will withdraw the necessary amount of SUI from its account to pay the Trust’s Sponsor’s Fee and any Additional Trust Expenses. The Sponsor pays the fees for the Additional Custodian. Anchorage Digital safeguards the private keys for the SUI held through a hardware security module located in the United States.

The filing also outlines provisions for blockchain forks. In the event of a fork of the Sui blockchain, Anchorage Digital may temporarily suspend services and determine whether to support either branch of the forked protocol. The agreement requires Anchorage Digital to maintain commercial crime insurance or a fidelity bond with limits of not less than $100 million in the aggregate, covering theft of money or property under its custody. The filing notes that shareholders cannot be assured that the Additional Custodian will maintain adequate insurance or that such coverage will cover losses with respect to the Trust’s SUI.