SCHEDULE 13D/A 0001140361-24-044040 0001441449 XXXXXXXX LIVE 3 Units of Limited Liability Company Interests 09/11/2025 false 0002020354 000000000 West Bay BDC LLC

200 West Street New York NY 10282

Qatar Investment Authority 974 4499 5919 Ooredoo Tower, Bldg. 14, Dafna St. (St. 801), Zone 61, P.O. 23224 Doha S3 00000 Copy to: William G. Farrar (212) 558-4000 Sullivan & Cromwell LLP 125 Broad Street New York NY 10004 0001441449 Qatar Investment Authority b OO S3 4783635.73 0 4783635.73 0 4783635.73 N 97.08 OO * Based on 4,927,640 Units issued and outstanding as of approximately August 12, 2025, based on information filed by the Issuer with the Securities and Exchange Commission on August 12, 2025, which does not give effect to the issuance of Units pursuant to Drawdown Notices dated September 4, 2025. Units of Limited Liability Company Interests West Bay BDC LLC 200 West Street New York NY 10282 This is Amendment No. 3 (the "Amendment No. 3") to the Schedule 13D filed with the U.S. Securities and Exchange Commission (the "SEC") by Qatar Investment Authority ("QIA"), the sovereign wealth fund of the State of Qatar, on October 16, 2024, as amended by Amendment No. 1 filed on November 22, 2024, as further amended by Amendment No. 2 filed on March 14, 2025 (as so amended, the "Schedule 13D"). This Amendment No. 3 amends and supplements or supersedes, as the case may be, the Schedule 13D as specifically set forth herein. Information reported and defined terms used in the Schedule 13D remain in effect except to the extent that they are amended, supplemented or superseded by information or defined terms contained in this Amendment No. 3. The information in Items 4, 5 and 6 of this Amendment No. 3 is incorporated into this Item 3 by reference. The response set forth in Item 3 of the Schedule 13D is amended and supplemented as follows: On September 11, 2025, the Issuer delivered a Drawdown Notice, dated September 4, 2025, to the Investor to purchase Units on September 22, 2025 in an aggregate amount equal to $45,000,000 (the "Fourth Purchase Amount") at the then-applicable price per unit, which has not been determined as of the date hereof. The source of funds to be used to purchase such Units is expected to be cash reserves of the State of Qatar. The Issuer has informed the Investor that the aggregate amount of Drawdown Notices dated September 4, 2025 is $46,350,000. The Fourth Purchase Amount represents approximately 97.09% of the aggregate amount of such Drawdown Notices. As of the date hereof, $130,500,000 of the Investor's Commitment has been drawn down by the Issuer. Item 4 of the Schedule 13D is amended, supplemented and superseded, as the case may be, as follows: The information in Items 3, 5 and 6 of this Amendment No. 3 is incorporated into this Item 4 by reference. Item 5 of the Schedule 13D is hereby amended and restated as follows: The information provided in this Item 5 is as of September 11, 2025 and does not give effect to the issuance of Units pursuant to the Drawdown Notices dated September 4, 2025. The Reporting Person has sole voting and dispositive power over 4,783,635.73 Units, representing 97.08% of the outstanding Units. The beneficial ownership percentage assumes that there are 4,927,640 Units outstanding, does not give effect to the issuance of Units pursuant to the Drawdown Notices dated September 4, 2025 and is based on information provided by the Issuer. Number of Units to which the Reporting Person has: (i) Sole power to vote or direct the vote: 4,783,635.73 (ii) Shared power to vote or direct the vote: 0.00 (iii) Sole power to dispose or direct the disposition: 4,783,635.73 (iv) Shared power to dispose or direct the disposition: 0.00 The information in Item 3 is incorporated herein by reference. The Reporting Person has not effected any transactions in Units during the past sixty days. The Reporting Person, through the Investor, expects to acquire Units on September 22, 2025 in the amount of the Fourth Purchase Amount at the then applicable price per Unit, at which time the Reporting Person will file Form 4 to report the acquisition of such Units. To the best knowledge of the Reporting Person, no person other than the Reporting Person has the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Units beneficially owned by the Reporting Person. Not applicable. Item 6 of the Schedule 13D is supplemented and superseded, as the case may be, as follows: The information in Items 3, 4 and 5 of this Amendment No. 3 is incorporated into this Item 6 by reference. Qatar Investment Authority /s/ Mohammed Fahad Al Khulaifi 09/16/2025