Securities and Exchange Commission Washington, D. C. 20549 Schedule 13-G/A Under the Securities and Exchange Act of 1934 MGIC Investment Corporation Common Stock CUSIP Number 552848103 Check the following box if a fee is being paid with this statement. [ ] CUSIP No. 552848103 1) Name of reporting person: Legg Mason, Inc. Tax Identification No: 52-1200960 2) Check the appropriate box if a member of a group: a) n/a b) n/a 3) SEC use only 4) Place of organization: Baltimore, Maryland Number of shares beneficially owned by each reporting person with: 5) Sole voting power: 8,731,210 6) Shared voting power: 4,098,369 7) Sole dispositive power: - 0 - 8) Shared dispositive power: 12,829,579 9) Aggregate amount beneficially owned by each reporting person: 12,829,579 10) Check if the aggregate amount in row (9) excludes certain shares: n/a 11) Percent of class represented by amount in row (9): 12.07% 12) Type of reporting person: HC Item 1a) Name of issuer: MGIC Investment Corporation Item 1b) Address of issuer's principal executive offices: MCIC Plaza, 250 E. Kilbourn Ave. Milwaukee, WI 53202 Item 2a) Name of person filing: Legg Mason, Inc. Item 2b) Address of principal business office: 100 Light Street Baltimore, Maryland 21202 Item 2c) Citizenship: Maryland Corporation Item 2d) Title of class of securities: Common Stock Item 2e) CUSIP number: 552848103 Item 3) If this statement is filed pursuant to Rule 13d-1(b), or 13d-2(b) , check whether the person filing is a: (a) [ ] Broker or dealer 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 ERISA of 1974 or Endowment Fund; see 240.13d-1(b)(ii)(F). (g) [X] Parent holding company, in accordance with 240.13d-1(b)(ii)(G). (h) [ ] Group, in accordance with 240.13d-1(b)(1)(ii)(H). Item 4) Ownership: (a) Amount beneficially owned: 12,829,579 (b) Percent of Class: 12.07% (c) Number of shares as to which such person has: (i) sole power to vote or to direct the vote: 8,731,210 (ii) shared power to vote or to direct the vote: 4,098,369 (iii) sole power to dispose or to direct the disposition of: - 0 - (iv) shared power to dispose or to direct the disposition of: 12,829,579 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: Legg Mason Funds Management, Inc., as investment adviser with discretion Batterymarch Financial Management, Inc., as investment adviser with discretion Branydwine Asset Management, Inc., as investment adviser with discretion Legg Mason Trust, fsb, as investment adviser with discretion Bartlett & Co., as investment adviser with discretion Legg Mason Capital Management, Inc., as investment adviser with discretion Legg Mason Wood Walker, Inc., as broker/dealer and investment adviser with discretion Perigee Investment Counsel, Inc., as investment adviser with discretion 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 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. 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: 3/14/01 Signature Timothy C. Scheve, Executive Vice President, Legg Mason, Inc. ------------------------------------------------------------- Name/Title Addendum to Schedule 13G/A filed by Legg Mason, Inc. Tax Identification No. 52-1200960 Shares of MGIC Investment Corporation owned a/o 12/31/00 CUSIP 552848103 Shares Sole Shared Sole Shared Name Class Owned V P V P D P D P Legg Mason Funds Management, Inc. IA 8,731,210 8,731,210 8,731,210 Battyermarch Financial Management, Inc. IA 846,600 846,600 846,600 Brandywine Asset Management, Inc. IA 100 100 100 Legg Mason Trust, fsb IA 5,900 5,900 5,900 Bartlett & Co. IA 400 400 400 Legg Mason Capital Management, Inc. IA 3,235,763 3,235,763 3,235,763 Legg Mason Wood Walker, Inc. BD, IA 9,224 9,224 9,224 Perigee Investment Counsel, Inc. IA 382 382 382 Shares Outstanding 106,329,000 % Owned 12.07%