Sec Form 4 Filing - Girardin Steve @ Blue Bird Corp - 2026-04-01

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

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1. Name and Address of Reporting Person Girardin Steve 2. Issuer Name and Ticker or Trading Symbol Blue Bird Corp [ BLBD] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 3920 ARKWRIGHT ROAD, SUITE 200 3. Date of Earliest Transaction (MM/DD/YY) 04/01/2026 (Street) MACON, GA31210 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 Special Voting Preferred Stock 04/01/2026 A 1 A 1 I See footnote ( 1 ) ( 2 ) Common Stock, par value $0.0001 per share 04/01/2026 A 2,297 ( 3 ) ( 4 ) A $ 0 2,297 D

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 Exchangeable Shares $ 0 04/01/2026 A 2,702,180 ( 5 ) ( 5 ) Common Stock, par value $0.0001 per share 2,702,180 ( 5 ) ( 1 ) 2,702,180 I See footnote ( 1 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Girardin Steve 3920 ARKWRIGHT ROAD, SUITE 200 MACON, GA31210 X Signatures /s/ Matthew Meziere as attorney-in-fact 04/09/2026 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The reported securities were acquired by Groupe Autobus Girardin Ltee, a corporation existing under the federal laws of Canada ("GAG"), in connection with the acquisition by the issuer of the remaining interest in its Micro Bird joint venture, as more fully described in the issuer's current report on Form 8-K filed with the Securities & Exchange Commission on April 2, 2026. The remaining interest in the Micro Bird joint venture was acquired from the sellers partly for $63,021,287 in cash and partly for (a) 2,702,180 Exchangeable Shares of MB Exchangeco Inc., a corporation existing under the laws of the Province of Ontario and a subsidiary of the issuer, and (b) 1 share of Special Voting Preferred Stock of the issuer. ( 2 )The Special Voting Preferred Stock share entitles the holder thereof to vote with the issuer's common stockholders and to cast the number of votes equal to the number of shares of the issuer's common stock that the Exchangeable Shares are exchangeable for. The reporting person may be deemed to have indirect beneficial ownership of such securities by virtue of his roles as a GAG shareholder, GAG manager and member of the GAG board of directors. The reporting person disclaims beneficial ownership of the reported securities except to the extent of his pecuniary interest therein. ( 3 )The award represents a grant of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the common stock of Blue Bird Corporation. ( 4 )The RSUs will vest on March 31, 2027; provided, however, that such RSUs will vest in full upon the occurrence of a "change in control" of the Company or if the reporting person's service terminates due to death, disability or due to completion of the reporting person's term of office as a director. Shares of common stock will be issued in settlement of the RSUs upon vesting and the earlier of the reporting person's compliance with the Company's applicable minimum stock ownership guidelines, termination of service as a director or a change in control event. ( 5 )The Exchangeable Shares are immediately exchangeable for shares of issuer's common stock, generally on a 1-for-1 basis, and while they do not expire, issuer, at its sole discretion, may force an exchange of any outstanding shares for shares of issuer's common stock after five years.

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).

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