SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

                                 Schedule 13G
                  Under the Securities Exchange Act of 1934
                                (Amendment No. )*


                               MGE Energy, Inc.
                            _____________________

                               (Name of Issuer)


                                 Common Stock
                              ____________________

                         (Title of Class of Securities)

                                   55277P104
                                 ____________

                                 (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:

         [X] Rule 13d-1(b)
         [ ] Rule 13d-(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 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).










                                     Page 1 of 5





CUSIP No. 55277P104                      13G                    Page 2 of 5

 1)     Name of Reporting Person
        S.S. or I.R.S. Identification No. of Reporting Person:

         MARSHALL & ILSLEY CORPORATION, I.D. No. 39-0452805

 2)     Check the Appropriate Box if a Member of a Group (See Instructions):
        (a)     [  ]
        (b)     [  ]

 3)     SEC Use Only

 4)     Citizenship or Place of Organization:     Wisconsin

Number of Shares Beneficially Owned by Each Reporting Person With:

     5)     Sole Voting Power:        89,072

     6)     Shared Voting Power:      776,888*

     7)     Sole Dispositive Power:   89,072

     8)     Shared Dispositive Power:  775,794*

 9)     Aggregate Amount Beneficially Owned by Each Reporting Person:  865,960*

     *Beneficial ownership of 772,019 shares is specifically disclaimed.  See
Item 4.

10)     Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See
Instructions):            N/A

11)     Percent of Class Represented by Amount in Row 9:   4.95%

12)     Type of Reporting Person (See Instructions):     HC




CUSIP No. 55277P104                       13G                    Page 3 of 5

Item 1(a).     Name of Issuer:  MGE Energy, Inc.

Item 1(b).     Address of Issuer's Principal Executive Offices:

                                133 South Blair Street
                                P.O. Box 1231
                                Madison, WI  53701

Item 2(a).     Name of Person Filing:      Marshall & Ilsley Corporation

Item 2(b).     Address or Principal Business Office or, if none, Residence:

                                770 North Water Street
                                Milwaukee, Wisconsin  53202

Item 2(c).     Citizenship:     Wisconsin Corporation

Item 2(d).     Title of Class of Securities:      Common Stock

Item 2(e).     CUSIP Number:         55277P104

Item 3.  If this statement is filed pursuant to rules 13d-1 (b) (1), or 13d-2
(b), check whether the person filing is a:
     (a) [  ]  Broker or dealer registered under Section 15 of the Act
     (b) [  ]  Bank as defined in Section 3 (a) (6) of the Act
     (c) [  ]  Insurance Company as defined in Section 3 (a) (19) of the Act
     (d) [  ]  Investment Company registered under Section 8 of the
               Investment Company Act
     (e) [  ]  Investment Adviser registered under Section 203 of the
               Investment Advisers Act of 1940
     (f) [  ]  Employee Benefit Plan, Pension fund which is subject to the
               provisions of the Employee Income Security Act of 1974 or
               Endowment fund:  see Sec. 240.13d-1(b)(1)(ii)(F)
     (g) [XX]  Parent Holding Company, in accordance with Sec. 240.13d-1
               (b)(1)(ii)(G) (Note:  See Item 7)
     (h) [  ]  Group, in accordance with Sec. 240.13d-1(b)(1)(h)(H)

Item 4.     Ownership.

     (a)     Amount Beneficially Owned:   865,960*
     (b)     Percent of Class:              4.95%

     (c)     Number of shares as to which such person has:
        (i)  Sole power to vote or to direct the vote:                 89,072
        (ii)  Shared power to vote or to direct the vote:              776,888*
        (iii)  Sole power to dispose or to direct the disposition of:  89,072
        (iv)  Shared power to dispose or to direct the disposition of: 775,794*

  *Includes 772,019 shares held in one or more employee benefit plans, where the
Marshall & Ilsley Trust Company N.A., as custodian, may be viewed as having
voting or dispositive authority in certain situations pursuant to Department of
Labor regulations or interpretations or federal case law.  Pursuant to SEC Rule
13d-4,




CUSIP No. 55277P104                      13G                    Page 4 of 5

inclusion of such shares in this statement shall not be construed as an
admission that the Reporting Person or its subsidiaries are, for purposes of
Sections 13(d) or 13(g) of the Act, the beneficial owners of such securities.

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

If this statement is being filed to report the fact that as of the date hereof
the reporting person has ceased to be the beneficial owner of more than five
percent of the class of securities, check the following [X].

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

In response to Item 6, bank trust beneficiaries and customers are known to have
the right to receive or the power to direct the receipt of dividends from or the
proceeds from the sale of the subject securities.  No such person is known to
possess such in interest relating to more than 5% of the class of subject
securities.

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

The parent holding company has filed this schedule pursuant to Rule
13d-1(b)(1)(ii)(g) and each relevant subsidiary hereby consents to the filing
of this statement on its behalf by the parent company:


                 Marshall & Ilsley Trust Company N.A.
                 a national banking association
                 (successor to Marshall & Ilsley Trust Company,
                  a Wisconsin banking corporation)
                 Tax Identification No. 39-1186267


Item 8.     Identification and Classification of Members of the Group.     Not
applicable

Item 9.     Notice of Dissolution of Group.     Not applicable




CUSIP No. 55277P104                       13G                    Page 5 of 5

Item 10.     Certification.

The following certification shall be included if the statement is filed pursuant
to Rule 13d-1 (b):

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 of 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.

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:  February 11, 2003

Signature: /s/ R. J. Erickson

Name/Title:  R. J. Erickson, Senior Vice President & General Counsel