QuickLinks -- Click here to rapidly navigate through this document
    UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934
(Amendment No. 10)*
   

MICROSOFT CORPORATION

(Name of Issuer)

Common Stock, $0.0000125 par value per share

(Title of Class of Securities)

 

 

594918104

 

 
   
(CUSIP Number)
   

December 31, 2002

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

        o      Rule 13d-1(b)

        o      Rule 13d-1(c)

        ý      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 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.            594918104        

             

1.   Names of Reporting Persons.
I.R.S. Identification Nos. of above persons (entities only).

 

 

William H. Gates III

 

 

 

 

2.   Check the Appropriate Box if a Member   (a)   o
    of a Group (See Instructions)   (b)   o

 

 

 

 

 

 

 

3.   SEC Use Only

 

 

 

 

 

 

 

4.   Citizenship or Place of Organization

 

 

United States of America

 

 

 

 

Number of Shares Beneficially Owned by Each Reporting Person With:   5.   Sole Voting Power

 

 

 

 

 

 

611,749,668
       
        6.   Shared Voting Power

 

 

 

 

 

 

-0-
       
        7.   Sole Dispositive Power

 

 

 

 

 

 

611,749,668
       
        8.   Shared Dispositive Power

 

 

 

 

 

 

-0-

9.   Aggregate Amount Beneficially Owned by Each Reporting Person

 

 

611,749,668

 

 

 

 

10.   Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)    o

 

 

 

 

 

 

 

11.   Percent of Class Represented by Amount in Row (9)

 

 

11.4%

 

 

 

 

12.   Type of Reporting Person (See Instructions)

 

 

IN

 

 

 

 

2


Item 1.

(a)   Name of Issuer

 

 

Microsoft Corporation (the "Issuer")
   
(b)   Address of Issuer's Principal Executive Offices

 

 

One Microsoft Way, Redmond, Washington 98052
   

Item 2.

(a)   Name of Person Filing

 

 

William H. Gates III
   
(b)   Address of Principal Business Office or, if none, Residence

 

 

One Microsoft Way, Redmond, Washington 98052
   
(c)   Citizenship

 

 

United States of America
   
(d)   Title of Class of Securities

 

 

Common Stock, $0.0000125 par value per share
   
(e)   CUSIP Number

 

 

594918104
   
Item 3.

 

Not Applicable.

3


Item 4. Ownership

(a)   Amount beneficially owned:

 

 

 

 

611,749,668
       
(b)   Percent of class:

 

 

 

 

 
        11.4%
       
(c)   Number of shares as to which the person has:
         
    (i)   Sole power to vote or to direct the vote

 

 

 

 

611,749,668
       
    (ii)   Shared power to vote or to direct the vote

 

 

 

 

 
        -0-
       
    (iii)   Sole power to dispose or to direct the disposition of

 

 

 

 

611,749,668
       
    (iv)   Shared power to dispose or to direct the disposition of

 

 

 

 

-0-
       

Item 5. Ownership of Five Percent or Less of a Class

        Not Applicable.

Item 6. Ownership of More than Five Percent on Behalf of Another Person

        Not Applicable.

Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company

        Not Applicable.


Item 8. Identification and Classification of Members of the Group

        Not Applicable.

Item 9. Notice of Dissolution of Group

        Not Applicable.

Item 10. Certification

        Not Applicable

4



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.


 

 

February 12, 2003

Date

 

 

WILLIAM H. GATES III

 

 

By:

 

/s/  
MICHAEL LARSON      
Name: Michael Larson*
Title: Attorney-in-fact
*
Duly authorized under Special Power of Attorney appointing Michael Larson attorney-in-fact, dated March 14, 2001, by and on behalf of William H. Gates III, filed as Exhibit B to Cascade's Amendment No. 1 to Schedule 13D with respect to Pan American Silver Corp. on March 19, 2001, SEC File Number 005-52919, and incorporated by reference herein.

5




QuickLinks

SIGNATURE