ISQ Open Infrastructure Co LLC

Item 3.02 Unregistered Sales of Equity Securities. As of June 1, 2026, ISQ Open Infrastructure Company LLC (the “Company”) issued and sold the following unregistered shares of the Company to investors for cash or for services rendered by the independent directors of the Boards of Directors of the Company (the “Board”): Class Number of Aggregate Shares Sold* Net Consideration* ────────────────────────────────────────────────────────── Series I F-STE Shares 75,837 $2,453,000 F-DTE Shares - - F-ITE Shares 46,123 1,498,375 F-JTE Shares - - STE Shares - - DTE Shares - - ITE Shares - - JTE Shares 66,124 2,152,000 ETE Shares - - Series II(1) F-S Shares 637,287 20,642,441 F-I Shares 64,943 2,115,000 F-J Shares - - I Shares 13,000 325,000 J Shares 102,973 2,585,000 E Shares 4,413 150,000 (1) Only reflects share classes outstanding as of June 1, 2026 held by third parties. Share and dollar amounts rounded to the nearest whole number. The Company issued such shares for total aggregate net consideration of $31,920,816 (the “Proceeds”). The offer and sale of the shares above were exempt from the registration provisions of the Securities Act of 1933, as amended, by virtue of Section 4(a)(2), including Regulation D (for sales to accredited investors) and/or Regulation S (for sales to non-U.S. investors outside of the United States) thereunder.

Item 8.01 Other Events. Asset Acquisitions In June 2026, the Company acquired two new assets for its portfolio: (i) an equity investment in Mercury Data Center Holdings Limited, a leading data center operator in Mexico, Central America and the Caribbean, and (ii) an equity investment in the Cube Safety HoldCo Limited, a leading European and North American provider in traffic management and road safety infrastructure. Transactional Net Asset Value On June 29, 2026, the operating manager of the Company determined the Transactional Net Asset Value per share, being the price at which sales of the Company’s shares are made, of the following classes of the Company’s shares as of May 31, 2026 ($ in thousands, except shares and per share data): Class Monthly Number Transactional of Transactional Net Asset Value Shares Net Asset Value* Outstanding* per Share as of May 31, 2026 ──────────────────────────────────────────────────────────────────────────────── Series I F-STE Shares $37,198 1,150,016 $32.35 F-DTE Shares 13,054 405,809 32.17 F-ITE Shares 3,513 108,151 32.49 F-JTE Shares 24,149 749,143 32.23 STE Shares 3 110 31.94 DTE Shares 3 110 32.06 ITE Shares 4 110 32.11 JTE Shares 662 20,329 32.54 ETE Shares 3 81 33.28 Series II(1)(2) F-S Shares 45,323 1,399,247 32.39 F-I Shares 25,071 769,837 32.57 F-J Shares 137,309 4,252,997 32.29 I Shares 325 13,000 25.00 J Shares 2,121 84,470 25.10 E Shares 15,703 462,007 33.99 * Share and dollar amounts rounded to the nearest whole number. (1) Only reflects share classes outstanding as of June 1, 2026 held by third parties. (2) Class I Shares were first sold on June 1, 2026 as reflected in the table above under Item 3.02 and were sold at an initial Transactional Net Asset Value per Share of $25.00. For additional information, please see details included in Exhibit 99.1 to this Current Report on Form 8-K, which is incorporated herein by reference. 2 June Distribution On June 30, 2026, the Company declared a special cash distribution on the following classes of the Company’s shares in the amounts per share set forth below: Class Net Distribution ────────────────────────────────────── Series I F-STE Shares $0.3424 F-DTE Shares 0.3424 F-ITE Shares 0.3424 F-JTE Shares 0.3424 STE Shares 0.3424 DTE Shares 0.3424 ITE Shares 0.3424 JTE Shares 0.3424 Series II F-S Shares 0.3424 F-I Shares 0.3424 F-J Shares 0.3424 I Shares 0.3424 J Shares 0.3424 E Shares 0.3424 The cash distribution for each class of shares is payable to holders of record at the close of business on June 29, 2026 and will be paid on or about August 4, 2026. The net distribution will be paid in cash or reinvested in shares of the Company for shareholders participating in the Company’s distribution reinvestment plan. The Company’s current liquidity position supports the Board’s consideration of regular future distributions; however, any future distributions, including the timing and amount of any quarterly distributions, will be determined by the Board in its discretion and will depend on the Company’s financial condition, results of operations, cash requirements, and other factors at the time of declaration.