Sec Form 4 Filing - BlackRock Portfolio Management LLC @ York Space Systems Inc. - 2026-08-04

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL OMB Number: 3235-0287 Expires: November 30, 2011 Estimated average burden hours per response... 0.5

1. Name and Address of Reporting Person BlackRock Portfolio Management LLC 2. Issuer Name and Ticker or Trading Symbol York Space Systems Inc. [ YSS] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 50 HUDSON YARDS 3. Date of Earliest Transaction (MM/DD/YY) 08/04/2026 (Street) NEW YORK, NY10001 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 08/04/2026 S 77,743 D $ 15.02 ( 4 ) 17,515,650 I See footnotes ( 1 ) ( 2 ) ( 3 ) Common Stock 08/04/2026 S 456,310 D $ 15.58 ( 5 ) 17,059,340 I See footnotes ( 1 ) ( 2 ) ( 3 ) Common Stock 08/05/2026 S 116,162 D $ 13.49 16,943,178 I See footnotes ( 1 ) ( 2 ) ( 3 ) Common Stock 08/05/2026 S 11,784 D $ 15.28 ( 6 ) 16,931,394 I See footnotes ( 1 ) ( 2 ) ( 3 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other BlackRock Portfolio Management LLC 50 HUDSON YARDS NEW YORK, NY10001 X Signatures BlackRock Portfolio Management LLC, By: /s/ David Maryles, Authorized Signatory 08/06/2026 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents shares of the Issuer's common stock held by the following funds and accounts under management by certain subsidiaries of BlackRock, Inc.: BlackRock Private Equity Co-Investments, 2021 Aggregator Cayman Ltd., BlackRock Growth Equity Fund Master Cayman Aggregator Ltd., BR POF IV CAYMAN MASTER FUND, L.P., BlackRock Private Opportunities Fund IV, L.P., BlackRock Private Opportunities Fund IV Master SCSp, TSCL Private Markets Cayman Fund Ltd., 1885 Private Opportunities Cayman Fund, Ltd., Heathrow Forest Opportunities Fund, L.P., Lincoln Pension Private Equity BR, L.P., NHRS Private Opportunities Fund, L.P., NDSIB Private Opportunities Fund Cayman Ltd., Mutual of Omaha OF Cayman, Ltd., BlackRock ERI Private Opportunities Master SCSp, Sullivan Way POF Cayman, Ltd, Total Alternatives Fund - Private Equity (B) LP, Total Alternatives Fund - Private Equity LP, 1824 Private Equity Fund, L.P., Tango Capital Opportunities Fund, L.P., BlackRock Private Investments Fund, ( 2 )OV Private Opportunities Cayman, Ltd., SONJ Opportunities Cayman, Ltd., Red River Direct Investment Fund III, L.P., MB BlackRock Holdings Cayman Ltd. and certain other funds and accounts managed by BlackRock Financial Management, Inc., BlackRock Institutional Trust Company, National Association, BlackRock Investment Management (UK) Limited and BlackRock Investment Management, LLC (collectively, the "Advised Funds and Accounts"). Each of BlackRock Portfolio Management LLC, the Advised Funds and Accounts and their respective direct or indirect managers, general partners and portfolio managers who share voting and investment power over the shares held by the Advised Funds and Accounts expressly disclaim beneficial ownership of the shares of common stock held by the Advised Funds and Accounts, except to the extent of their pecuniary interest therein, ( 3 )and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of the reported shares for purposes of Section 16 or for any other purposes. ( 4 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $14.28 to $15.27, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth herein. ( 5 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $15.28 to $16.00, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth herein. ( 6 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $15.00 to $15.31, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth herein.

Remarks: In accordance with SEC Release No. 34-39538 (January 12, 1998), BlackRock Portfolio Management LLC is reporting Issuer securities beneficially owned, or deemed to be beneficially owned, by certain business units (collectively, the "Reporting Business Units") of BlackRock, Inc. and its subsidiaries and affiliates. This filing does not include Issuer securities, if any, beneficially owned by other business units whose beneficial ownership of securities is disaggregated from that of the Reporting Business Units in accordance with such release.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.