QuickLinks -- Click here to rapidly navigate through this document

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934
(Amendment No.  )*

THE MIDDLEBY CORPORATION
(Name of Issuer)

Common Stock, par value $0.01 per share
(Title of Class of Securities)

596278101
(CUSIP Number)

Nathaniel Sack, Esq.
Seyfarth Shaw LLP
55 East Monroe Street
Suite 4200
Chicago, IL 60603-5803
(312) 346-8000
(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

December 9, 2003
(Date of Event Which Requires Filing of this Statement)

        If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. o

        *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 cover 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.    596278101


1.   Names of Reporting Persons
S.S. or I.R.S. Identification Nos. of above persons (entities only)
WILLIAM F. WHITMAN, JR. DECLARATION OF TRUST
2.   Check the Appropriate Box if a Member of a Group   (a)  ý
                (b)  o
3.   SEC Use Only

 		           
4.   Source of Funds (See Instructions)
N/A
5.   Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e)
                o
6.   Citizenship or Place of Organization
USA

Number of
Shares
 
7.
 
Sole Voting Power
0
 
 
Beneficially  
Owned by
Each		   8.   Shared Voting Power
1,898,974*		    
Reporting  
Person
With		   9.   Sole Dispositive Power
0
 		   
       
        10.   Shared Dispositive Power
1,898,974*
 		   
11.   Aggregate Amount Beneficially Owned by Each Reporting Person
1,898,974*
12.   Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)    
                o
13.   Percent of Class Represented by Amount in Row (11)
20.6%
14.   Type of Reporting Person (See Instructions)
OO
*
Includes shares beneficially owned by a trust whose beneficiary is the spouse of the reporting person's grantor.

Page 2 of 6
1.   Names of Reporting Persons
S.S. or I.R.S. Identification Nos. of above persons (entities only)
THOMAS C. DANZIGER
2.   Check the Appropriate Box if a Member of a Group   (a)  ý
                (b)  o
3.   SEC Use Only

 		           
4.   Source of Funds (See Instructions)
N/A
5.   Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e)
                o
6.   Citizenship or Place of Organization
USA

Number of
Shares
 
7.
 
Sole Voting Power
0
 
 
Beneficially  
Owned by
Each		   8.   Shared Voting Power
1,898,974**		    
Reporting  
Person
With		   9.   Sole Dispositive Power
0
 		   
       
        10.   Shared Dispositive Power
1,898,974**
 		   
11.   Aggregate Amount Beneficially Owned by Each Reporting Person
1,898,974**
12.   Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)    
                ý***
13.   Percent of Class Represented by Amount in Row (11)
20.6%
14.   Type of Reporting Person (See Instructions)
IN
**
Includes certain shares deemed to be beneficially owned by reporting person as trustee of two trusts.

***
Pursuant to Rule 13d-4 under the Securities Exchange Act of 1934, as amended, reporting person disclaims beneficial ownership of the securities reported in this Schedule 13D.

Page 3 of 6


Item 1.    Security and Issuer.

        This statement on Schedule 13D (this "Statement" or this "Schedule 13D") relates to the common stock, par value $.01 per share (the "Common Stock"), of The Middleby Corporation, a Delaware corporation (the "Issuer" or "Middleby"). The principal executive office of the Issuer is located at 1400 Toastmaster Drive, Elgin, Illinois 60120.


Item 2.    Identity and Background.

(a) - (c)   This Statement is being filed by a group consisting of the following:

 
 
(i)
 
William F. Whitman, Jr. Declaration of Trust (the "Trust"); and
    (ii)   Thomas C. Danziger, an individual, as sole trustee of the Trust ("Trustee").

        The above are collectively referred to as the "Reporting Persons".

        The principal business address of the Trust is c/o The Middleby Corporation, 1400 Toastmaster Drive, Elgin, Illinois 60120.

        Trustee is the sole trustee of the Trust. Trustee's present principal occupation is attorney. Trustee's business address is Danziger & Danziger, 405 Park Avenue, New York, New York 10022.

        (d)   During the last five years, none of the Reporting Persons has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).

        (e)   During the last five years, none of the Reporting Persons has not a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

        (f)    Trustee is a citizen of the United States. The Trust was formed in the United States.


Item 3.    Source and Amount of Funds or Other Consideration.

        N/A


Item 4.    Purpose of Transaction.

        For tax planning purposes, on December 9, 2003, William F. Whitman, Jr. (the grantor of the Trust) assigned an aggregate of 1,643,674 shares of Common Stock that he beneficially owns to the Trust and his spouse assigned an aggregate of 255,300 shares of Common Stock to another trust whose grantor is Mr. Whitman's spouse. Trustee is the sole trustee of both trusts. The Whitmans, the trusts, and Trustee did not receive or pay any consideration in connection with such transactions. Under the terms of certain Irrevocable Trust Agreements, Mr. Whitman and his spouse have the right to acquire beneficial ownership of such securities within 60 days of the transfer.

        Mr. Whitman is Chairman of the Board of the Issuer.

        Trustee is the spouse of Laura B. Whitman, who is a director of the Issuer and the daughter of Mr. Whitman.

        As of the date of this Amendment to this Schedule 13D, Reporting Persons have no plans or proposals which relate to, or would result in, any of the actions referred to in clauses (a) through (j) of Item 4 of Schedule 13D.

        As the Reporting Persons meet the definition of a "group" for purposes of Section 13(d) of the Securities Act, this Schedule 13D has been filed by the Reporting Persons.

Page 4 of 6


Item 5.    Interest in Securities of the Issuer.

        (a)   The Trust and the Trustee are each deemed to beneficially own 1,898,974 shares of Common Stock which represents approximately 20.6% of the 9,207,874 shares of Common Stock outstanding as reported by the Issuer in its Proxy Statement on Schedule 14A, which was filed on November 24, 2003.

        (b)   Pursuant to the terms of certain Irrevocable Trust Agreements, the Trustee has the sole authority to direct the disposition and voting of the shares of Common Stock owned by the trusts.

        (c)   Other than the transaction described in Item 4 above, no transactions have been effected by any of the Reporting Persons during the past sixty days.

        (d)   The trusts have the right to receive any dividends from, or proceeds from the sale of, the securities. Trustee has the power to direct the receipt of dividends from, or proceeds from the sale of, such securities.

        (e)   N/A.


Item 6.    Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.

        Pursuant to the terms of certain Irrevocable Trust Agreements, Trustee has the sole authority to direct the disposition and voting of the shares of Common Stock owned by the Trust and the trust granted by Mr. Whitman's spouse. However, under the terms of those agreements, Mr. Whitman and his spouse have the right to acquire beneficial ownership of such securities within 60 days of the transaction reported in this Schedule 13D.


Item 7.    Material to be Filed as Exhibits.

Exhibit 1   Irrevocable Trust Agreement, dated November 29, 2003, between William F. Whitman, Jr., as Grantor of the Trust, and Thomas C. Danziger, as Trustee of the Trust.

Exhibit 2
 
Irrevocable Trust Agreement, dated November 29, 2003, between Barbara Whitman, as Grantor of the Trust, and Thomas C. Danziger, as Trustee of the Trust.

Page 5 of 6


SIGNATURE

        After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: December 23, 2003


WILLIAM J. WHITMAN, JR. DECLARATION OF TRUST
 

Signature:
/s/ Thomas C. Danziger, Sole Trustee
 

Name/Title:
Thomas C. Danziger, Sole Trustee
 

THOMAS C. DANZIGER
 

Signature:
/s/ Thomas C. Danziger
 

Name/Title:
Thomas C. Danziger
 

ATTENTION:
INTENTIONAL MISSTATEMENTS OR OMMISSIONS OF FACT CONSTITUTE FEDERAL CRIMINAL VIOLATIONS (SEE 18 U.S.C. 1001).

Page 6 of 6



QuickLinks

SIGNATURE