Filing Details

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Initial Filing)* Mattel, Inc. ________________________________________________________ (Name of Issuer) Common Stock _______________________________________________________ (Title of Class and Securities) 577081102 _______________________________________________________ (CUSIP Number of Class of Securities) December 31, 2021 ___________________________________________ (Date of Event which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this Schedule is filed: /X/ Rule 13d-1(b) / / Rule 13d-1(c) / / Rule 13d-1(d) * The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior page. The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 577081102 13G _____________________________________________________________________________ (1) NAMES OF REPORTING PERSONS Southeastern Asset Management, Inc. I.D. No. 62-0951781 _____________________________________________________________________________ (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) (b) X _____________________________________________________________________________ (3) SEC USE ONLY _____________________________________________________________________________ (4) CITIZENSHIP OR PLACE OF ORGANIZATION Tennessee _____________________________________________________________________________ : (5) SOLE VOTING POWER : (Discretionary Accounts) NUMBER OF SHARES BENEFICIALLY : 3,185,478 shares OWNED BY EACH REPORTING PERSON __________________________________________ WITH : (6) SHARED OR NO VOTING POWER 12,918,636 shares (Shared) 4,124,226 shares (No Vote) __________________________________________ : (7) SOLE DISPOSITIVE POWER (Discretionary Accounts) : 8,144,030 shares __________________________________________ : (8) SHARED DISPOSITIVE POWER : 12,084,310 shares (Shared) 0 shares (None) _____________________________________________________________________________ (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 20,228,340 shares _____________________________________________________________________________ (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES _____________________________________________________________________________ (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 5.8 % _____________________________________________________________________________ (12) TYPE OF REPORTING PERSON IA _____________________________________________________________________________CUSIP No. 577081102 13G _____________________________________________________________________________ (1) NAMES OF REPORTING PERSONS O. Mason Hawkins I.D. No. XXX-XX-XXXX _____________________________________________________________________________ (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) (b) X _____________________________________________________________________________ (3) SEC USE ONLY _____________________________________________________________________________ (4) CITIZENSHIP OR PLACE OF ORGANIZATION Citizen of United States _____________________________________________________________________________ : (5) SOLE VOTING POWER : (Discretionary Accounts) NUMBER OF SHARES BENEFICIALLY : None OWNED BY EACH REPORTING PERSON __________________________________________ WITH : (6) SHARED VOTING POWER : None __________________________________________ : (7) SOLE DISPOSITIVE POWER : None __________________________________________ : (8) SHARED DISPOSITIVE POWER : None _____________________________________________________________________________ (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON None (See Item 3) _____________________________________________________________________________ (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES _____________________________________________________________________________ (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.0% _____________________________________________________________________________ (12) TYPE OF REPORTING PERSON IN _____________________________________________________________________________Item 1. (a). Name of Issuer: Mattel, Inc. ("issuer") (b). Address of Issuer's Principal Executive Offices: 333 Continental Blvd. El Segundo, CA 90245-5012 Item 2. (a) and (b). Names and Principal Business Addresses of Persons Filing: (1) Southeastern Asset Management, Inc. 6410 Poplar Ave., Suite 900 Memphis, TN 38119 (2) Mr. O. Mason Hawkins Chairman of the Board and C.E.O. Southeastern Asset Management, Inc. 6410 Poplar Ave., Suite 900 Memphis, TN 38119 (c). Citizenship: Southeastern Asset Management, Inc. - A Tennessee corporation Mr. O. Mason Hawkins - U.S. Citizen (d). Title of Class of Securities: Common Shares ("the Securities"). (e). Cusip Number: 577081102 Item 3. If this statement is filed pursuant to Rules 13d-1 (b) or 13d-2 (b), check whether the person filing is a: (e). Investment Adviser registered under Section 203 of the Investment Advisers Act of 1940. This statement is being filed by Southeastern Asset Management, Inc. as a registered investment adviser. All of the securities covered by this report are owned legally by Southeastern's investment advisory clients and none are owned directly or indirectly by Southeastern. As permitted by Rule 13d-4, the filing of this statement shall not be construed as an admission that Southeastern Asset Management, Inc. is the beneficial owner of any of the securities covered by this statement. (g). Parent Holding Company. This statement is also being filed by Mr. O. Mason Hawkins, Chairman of the Board and C.E.O. of Southeastern Asset Management, Inc. in the event he could be deemed to be a controlling person of that firm as the result of his official positions with or ownership of its voting securities. The existence of such control is expressly disclaimed. Mr. Hawkins does not own directly or indirectly any securities covered by this statement for his own account. As permitted by Rule 13d-4, the filing of this statement shall not be construed as an admission that Mr. Hawkins is the beneficial owner of any of the securities covered by this statement. Item 4. Ownership: (a). Amount Beneficially Owned: (At 12/31/21) 20,228,340 shares (b). Percent of Class: (At 12/31/21) 5.8 % Above percentage is based on 350,341,243 shares of Common Shares outstanding. (c). Number of shares as to which such person has: (i). sole power to vote or to direct the vote: 3,185,478 shares (ii). shared or no power to vote or to direct the vote: Shared - 12,918,636 shares. Securities owned by the following series of Longleaf Partners Funds Trust, an open-end management investment company registered under the Investment Company Act of 1940, as follows: Longleaf Partners Fund - 5,388,375 Longleaf Partners Small-Cap Fund - 6,269,977 Longleaf Partners Global Fund - 399,290 Other Shared - 860,994 No Power to Vote - 4,124,226 shares. (iii). sole power to dispose or to direct the disposition of: 8,144,030 shares (iv). shared or no power to dispose or to direct the disposition of: Shared - 12,084,310 shares Securities owned by the following series of Longleaf Partners Funds Trust, an open-end management investment company registered under the Investment Company Act of 1940, as follows: Longleaf Partners Fund - 5,388,375 Longleaf Partners Small-Cap Fund - 6,269,977 Longleaf Partners Global Fund - 399,290 Other Shared - 26,668 No Power - 0 shares. Item 5. Ownership of Five Percent or Less of a Class: N/A Item 6. Ownership of More than Five Percent on Behalf of Another Person: N/A Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company: N/A Item 8. Identification and Classification of Members of the Group: N/A Item 9. Notice of Dissolution of Group: N/A Item 10. Certification: By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired in the ordinary course of business and were not acquired for the purpose and do not have the effect of changing or influencing the control of the issuer of such securities and were not acquired in connection with or as a participant in any transaction having such purposes or effect. Signatures After reasonable inquiry and to the best of the knowledge and belief of the undersigned, the undersigned certifies that the information set forth in this statement is true, complete, and correct. Dated: February 14, 2022 Southeastern Asset Management, Inc. By /s/ Andrew R. McCarroll _______________________________________________ Andrew R. McCarroll Vice President and General Counsel O. Mason Hawkins, Individually /s/ O. Mason Hawkins _______________________________________________ Joint Filing Agreement In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, the persons or entities named below agree to the joint filing on behalf of each of them of this Schedule 13G with respect to the Securities of the Issuer and further agree that this joint filing agreement be included as an exhibit to this Schedule 13G. In evidence thereof, the undersigned hereby execute this Agreement as of February 14, 2022. Southeastern Asset Management, Inc. By /s/ Andrew R. McCarroll ______________________________________________ Andrew R. McCarroll Vice President and General Counsel O. Mason Hawkins, Individually /s/ O. Mason Hawkins _______________________________________________ 1 1 MAT13G-0.doc SCHEDULE 13G - Mattel, Inc. ("Issuer") Initial Filing 1 MAT13G-0.doc