SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549



 
 

SCHEDULE 13G/A

(Rule 13d-102)
 
 

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO RULES 13d-1(b), (c), AND (d) AND AMENDMENTS THERETO FILED

PURSUANT TO RULE 13d-2(b)

( AMENDMENT 3)








 
 

CORPORATE OFFICE PROPERTIES TRUST

( NAME OF ISSUER )
 
 

COMMON STOCK

(Title of Class of Securities)
 
 

22002T108

(CUSIP Number)
 
 

DECEMBER 29, 2006

(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)

 



 
CUSIP No. 22002T108
13G/A
Page 1 of 3 pages



 
1.
Names of reporting persons Security Capital Research & Management Incorporated 
  I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) 36-4130398

 



 
2.
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) 
    (b) 



 
3.
SEC USE ONLY



 
4.
CITIZENSHIP OR PLACE OF ORGANIZATION
  Delaware

 



 
NUMBER OF
5.
SOLE VOTING POWER 1,944,529
SHARES
     
BENEFICIALLY
6.
SHARED VOTING POWER 0
OWNED BY
     
EACH
7.
SOLE DISPOSITIVE POWER 2,664,603
REPORTING
     
PERSON WITH
8.
SHARED DISPOSITIVE POWER 0

 



 
9.
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
    2,664,603



 
10.
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES  
  CERTAIN SHARES  

 



 
11.
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
  6.2%

 



 
12.
TYPE OF REPORTING PERSON* IA

 


Item 1(a). Name of Issuer:
  CORPORATE OFFICE PROPERTIES TRUST
Item 1(b). Address of Issuer's Principal Executive Offices:
  8815 CENTER PARK DRIVE

SUITE 400  COLUMBIA, MD  21045

   
Item 2(a). Name of Person Filing:
  Security Capital Research & Management Incorporated 
Item 2(b). Address of Principal Business Office or, if None, Residence:
  10 South Dearborn Street, Suite 1400
  Chicago, Illinois 60603
Item 2(c). Citizenship
  Delaware
Item 2(d). Title of Class of Securities:
  COMMON STOCK 
  Unless otherwise noted, security being reported is common stock
Item 2(e). CUSIP Number: 22002T108
Item 3 If this Statement is Filed Pursuant to Rule 13d-1(b), or 13d-2(b)
  Or (c), Check Whether the Person Filing is a :
 
(a)
Broker or dealer registered under Section 15 of the Exchange Act;
 
(b)
Bank as defined in Section 3(a)(6) of the Exchange Act;
 
(c)
Insurance company as defined in Section 3(a)(19) of the
      Exchange Act;
 
(d)
Investment company registered under Section 8 of the Investment
      Company Act;
 
(e)
       X An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E);
 
(f)
An employee benefit plan or endowment fund in accordance with
      Rule 13d-1(b)(1)(ii)(F);
 
(g)
 
A parent holding company or control person in accordance with
      Rule 13d-1(b)(1)(ii)(G);
 
(h)
A savings association as defined in Section 3(b) of the Federal
      Deposit Insurance Act;
 
(i)
A church plan that is excluded from the definition of an 
      Investment company under Section 3(c)(14) of the Investment 
      Company act;
 
(j)
Group, in accordance with Rule 13d-1(b)(1)(ii)(J).
If this statement is filed pursuant to Rule 13d-1(b), check this box.
X

 


Page 2 of 3 pages


Item 4. Ownership
  Provide the following information regarding the aggregate number and
  Percentage of the class of securities of issuer identified in Item 1.
 
(a)
Amount beneficially owned: 2,664,603
    Including 0 shares where there is a Right to Acquire.
 
(b)
Percent of class: 6.2%
 
(c)
Number of shares as to which such person has:
   
(i)
Sole power to vote or to direct the vote: 1,944,523 
   
(ii)
Shared power to vote or to direct the vote: 0
   
(iii)
Sole power to dispose or to direct the disposition of: 2,664,603
   
(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
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. ( )

 
 
Item 6. Ownership of More than Five Percent on Behalf of Another Person.
Security Capital Research & Management Incorporated is the beneficial owner of 2,664,603 shares of the
issuer's common stock on behalf of other persons known to have one or more of
the following:
  the right to receive dividends for such securities;
  the power to direct the receipt of dividends from such securities;
  the right to receive the proceeds from the sale of such securities;
  the right to direct the receipt of proceeds from the sale of such securities;
No such person is known to have an interest in more than 5% of the class of
securities reported herein unless such person is identified below.

 
 
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. Certifications

 
 
By signing below I certify that, to the best of my knowledge and belief,
the securities referred to above were not acquired and are not held for the
purpose of or with the effect of changing or influencing the control of the
issuer of the securities and were not acquired and are not held in connection
with or as a participant in any transaction having that purpose or effect.

 
 
 


Page 3 of 3 pages



 
 
 
 
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.

Dated: FEBRUARY 15,2007 
Security Capital Research & Management Incorporated 
 
By: /s/ Michael J. Heller
 
--------------------------------------
 
Michael J. Heller 
 
Vice President and Controller

 
 
 
 
 
 
 
 
The original statement shall be signed by each person on whose behalf the statement
is filed or his authorized representative. If the statement is signed on behalf of
a person by his authorized representative (other than an executive officer or general
partner of the filing person), evidence of the representative's authority to sign on
behalf of such person shall be filed with the statement, provided, however, that a 
power of attorney for this purpose which is already on file with the commission may
be incorporated by reference. The name and any title of each person who signs the
the statement shall be typed or printed beneath his signature.