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

SCHEDULE 13GA

Under the Securities Exchange Act of 1934
(Amendment No.  1)*


Corporate Office Properties Trust
NAME OF ISSUER:


Common Shares of Beneficial Interest, par value $0.01 per share
TITLE OF CLASS OF SECURITIES


22002T108
CUSIP NUMBER


December 31, 2009
(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)

* 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).
 
Continued on following pages
Page 1 of 6 Pages


 
 
 


 
SCHEDULE 13GA
  
     
CUSIP No.: 22002T108
  
Page 2 of 6 Pages

1.
Names of Reporting Persons.
 
Nomura Asset Management Co., Ltd.
2.
Check the Appropriate Box if a Member of a Group
 
(a) [   ]
 
(b) [X]
3.
SEC Use Only
4.
Citizenship or Place of Organization
 
Tokyo, Japan
Number of
Shares
Beneficially
Owned by Each
Reporting
Person With
5.
Sole Voting Power
1,057,221
6.
Shared Voting Power
0
7.
Sole Dispositive Power
355,510
8.
Shared Dispositive Power
0
9.
Aggregate Amount Beneficially Owned by Each Reporting Person
 
1,057,221
10.
Check if the Aggregate Amount in Row (9) Excludes Certain Shares
 
[   ]
11.
Percent of Class Represented by Amount in Row (9)
 
1.82% based on 58,248,932 shares outstanding as of October 23, 2009.
12.
Type of Reporting Person
 
IA
 


 
 
 

Page 3 of 6 Pages
Item 1 (a)
Name of Issuer:
   
 
Corporate Office Properties Trust (the “Issuer”)
   
Item 1(b)
Address of Issuer’s Principal Executive Offices:
   
 
6711 Columbia Gateway Drive, Suite 300, Columbia, MD 21046
   
Item 2(a)
Name of Person Filing:
   
This Statement is filed on behalf of Nomura Asset Management Co., Ltd. (“NAM”). This Statement relates to Shares (as defined herein) held for the accounts of Global High Income Stock Fund Mother Fund (“Global High Income Stock Fund Mother”), Nomura US-REIT Open Mother Fund (“Nomura US-REIT Open Mother”), US-REIT Mother Fund (“US-REIT Mother”), Global Attractive Dividend Stock Fund Mother Fund (“Global Attractive Dividend Stock Fund Mother”), International REIT Index Mother Fund (“International REIT Index Mother”), Nomura World REIT Mother Fund (“Nomura World REIT Mother”), World REIT Index Mother Fund (“World REIT Index Mother”), Nomura LaSalle Global REIT Mother Fund (“Nomura LaSalle Global REIT Mother”) and Nomura Partners Funds, Inc. (“Nomura Partners Funds”).
 
NAM serves as investment manager to each of the Global High Income Stock Fund Mother, Nomura US-REIT Open Mother, US-REIT Mother, Global Attractive Dividend Stock Fund Mother, International REIT Index Mother, Nomura World REIT Mother, World REIT Index Mother, Nomura LaSalle Global REIT Mother and Nomura Partners Funds. In such capacity, NAM may be deemed to have voting and dispositive power over the Shares held for the accounts of each of the Global High Income Stock Fund Mother, Global Attractive Dividend Stock Fund Mother, International REIT Index Mother, World REIT Index Mother and Nomura Partners Funds.  NAM may be deemed to have voting power only over the Shares held for the accounts of each of the Nomura US-REIT Open Mother, US-REIT Mother, Nomura World REIT Mother and Nomura LaSalle Global REIT Mother.
 
Item 2(b)
Address of Principal Office or, if none, Residence:
   
        The address of the principal office of NAM is 1-12-1, Nihonbashi, Chuo-ku, Tokyo, Japan 103-8260
 
Item 2(c)
Citizenship:
   
 
NAM is a Japanese corporation
   
Item 2(d)
Title of Class of Securities:
   
 
Common Shares of Beneficial Interest, par value $0.01 per share (the “Shares”)
   
Item 2(e)
CUSIP Number:
   
 
22002T108
   
Item 3(e).
[X] An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E)
   
Item 4
Ownership:
   
Item 4(a)
Amount Beneficially Owned:
   
 
 

 
 
 
 

Page 4 of 6 Pages

        As of December 31, 2009, NAM may be deemed to be the beneficial owner of 1,057,221 Shares. This amount consists of: (1) 115,200 Shares held for the account of Global High Income Stock Fund Mother, (2) 13,100 Shares held for the account of Nomura US-REIT Open Mother, (3) 672,840 Shares held for the account of US-REIT Mother, (4) 196,400 Shares held for the account of Global Attractive Dividend Stock Fund Mother, (5) 40,400 Shares held for the account of International REIT Index Mother, (6) 12,850 Shares held for the account of Nomura World REIT Mother, (7) 2,910 Shares held for the account of World REIT Index Mother, (8) 2,921 Shares held for the account of Nomura LaSalle Global REIT Mother and (9) 600 Shares held for the account of Nomura Partners Funds.
 
Item 4(b)
Percent of Class:
   
The number of Shares of which NAM may be deemed to be the beneficial owner of constitutes approximately 1.82% of the total number of Shares outstanding (based upon the information provided by the issuer in its most recently-filed quarterly report on Form 10-Q, there were 58,248,932 Shares outstanding as of October 23, 2009).
 
Item 4(c)
Number of Shares of which such person has:
   
(i) Sole power to vote or direct the vote:
1,057,221
   
(ii) Shared power to vote or direct the vote:
0
   
(iii) Sole power to dispose or direct the disposition of:
355,510
   
(iv) Shared power to dispose or direct the disposition of:
             0
   
Item 5
Ownership of 5% 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 5% on Behalf of Another Person:
   
 
NAM retained Heitman Real Estate Securities LLC (“Heitman”) as a sub-investment adviser to each of the Nomura US-REIT Open Mother and US-REIT Mother.  NAM retained LaSalle Investment Management (Securities), L.P. (“LaSalle”) as a sub-investment adviser to each of the Nomura World REIT Mother and Nomura LaSalle Global REIT Mother. NAM has given dispositive power to Heitman and LaSalle and the right to receive the power to direct the receipt of dividends from, or proceeds from the sale of 685,940 and 15,771 Shares, respectively (approximately 1.18% and 0.03% respectively of the total number of Shares outstanding.)
   
Item 7
Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company:
   
 
This Item 7 is not applicable.
   
Item 8
Identification and Classification of Members of the Group:
   
 
This Item 8 is not applicable.
   
Item 9
Notice of Dissolution of Group:
   
 
This Item 9 is not applicable.
   

 
 
 

Page 5 of 6 Pages

Item 10
Certification:
   
      By signing below each of the Reporting Persons certifies that, to the best of their 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 6 of 6 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.

Date:  March 26, 2010
  
NOMURA ASSET MANAGEMENT CO., LTD.
 
By:           /s/ Kenji Kitagawa
Name:     Kenji Kitagawa
Title:       Managing Director