Grayscale Sui Staking ETF (GSUI): enters custody agreement with Anchorage Digital

What happened The filing reports that on Sep 29, 2026, Grayscale Investments Sponsors, LLC, on behalf of the Grayscale Sui Staking ETF (the Trust), entered into the Sixth Amendment (the "Anchorage Digital Amendment") to the Master Custody Service Agreement with Anchorage Digital Bank N.A., making the Trust a party to that custody agreement. The filing says Anchorage Digital will provide custody and safekeeping services for a portion of the Trust’s SUI holdings and that the sponsor intends to utilize Anchorage Digital’s services. The filing says the Trust’s existing custody arrangement with Coinbase Custody Trust Company, LLC is unaffected and that Coinbase remains the Trust’s primary custodian.

Key details

• date of agreement: Sep 29, 2026; original Master Custody Service Agreement dated Aug 8, 2025.
• custody scope: Anchorage Digital will custody a portion of the Trust’s SUI; the sponsor will, in its sole discretion, determine amounts held at each custodian and has not yet determined the total amount to move.
• operations and fees: Anchorage Digital generates and retains private keys, stores keys in a hardware security module located in the United States, and fees paid to the additional custodian are a sponsor-paid expense.
• risk and insurance: in a fork of the Sui blockchain Anchorage Digital may suspend services and may decide whether to support either branch; Anchorage Digital is required to maintain insurance including commercial crime insurance or a fidelity bond with limits of not less than $100,000,000 in the aggregate.

Why it may matter Item 1.01 was reported: entry into a material definitive agreement (a custody services agreement amendment) covering custody and safekeeping of a portion of the Trust’s SUI holdings. This filing does not show why the insider traded or why the company acted.