Exhibit 99.1

Earnings Release & Supplemental Information — Unaudited

September 30, 2011

OVERVIEW:		Section I
	Earnings Release	—
	Summary Description	1
	Research Coverage	2
	Selected Financial Summary Data	3-4
FINANCIAL STATEMENTS:		Section II
	Quarterly Consolidated Balance Sheets	5
	Consolidated Statements of Operations	6
	Consolidated Reconciliations of FFO and AFFO	7
PORTFOLIO INFORMATION:		Section III
	Summary of Wholly Owned Operating Office Properties by Region	8
	Property Occupancy Rates by Region by Quarter for Wholly Owned Office Properties	9
	Summary of Operating, Construction and Redevelopment Office Properties Ownership	9
	Office Properties by Region — Wholly Owned Office Properties	10-15
	Renewal Analysis for Wholly Owned Office Properties	16
	Lease Expiration Analysis for Wholly Owned Office Properties	17
	Top 20 Tenants — Wholly Owned Office Properties	18
	Real Estate Revenues & NOI by Region	19
	Same Office Properties Average Occupancy by Region	20
	Same Office Property Revenues & NOI by Region	21
INVESTING ACTIVITY:		Section IV
	Acquisition Summary for Wholly Owned Operating Office Properties	22
	Disposition Summary for Wholly Owned Operating Office Properties	22
	Construction, Pre-Construction, Future Projects, Redevelopment and Controlled Land Summary	23
	Controlled Land	24
	Summary of Construction and Redevelopment Projects	25
	Summary of Pre-Construction and Future Projects	26
	Office Property Construction Placed into Service in 2011	27
	Construction Leasing Trend Analysis Over Previous Five Quarters	28
WHOLESALE DATA CENTER:		Section V
	Wholesale Data Center Summary	29
CAPITALIZATION:		Section VI
	Quarterly Common Equity Analysis	30
	Quarterly Preferred Equity and Total Market Capitalization Analysis	31
	Dividend Analysis	32
	Debt Analysis	33
	Debt Maturity Schedule	34
JOINT VENTURES:		Section VII
	Summary of Consolidated Joint Ventures	35
	Summary of Unconsolidated Joint Ventures	36
RECONCILIATIONS & DEFINITIONS:		Section VIII
	Supplementary Reconciliations of Non-GAAP Measures	37-38
	Definitions	39-42

Please refer to the section entitled “Definitions” for definitions of non-GAAP measures and other terms we use herein that may not be customary or commonly known.

	6711 Columbia Gateway Drive, Suite 300 Columbia, Maryland 21046 Telephone 443-285-5400 Facsimile 443-285-7650 www.copt.com NYSE: OFC NEWS RELEASE
FOR IMMEDIATE RELEASE	IR Contacts:
	Stephanie Krewson	Michelle Layne
	VP, Investor Relations	Investor Relations Specialist
	443-285-5453	443-285-5452
	stephanie.krewson@copt.com	michelle.layne@copt.com

COPT REPORTS THIRD QUARTER 2011 RESULTS

COLUMBIA, MD October 27, 2011 — Corporate Office Properties Trust (COPT) (NYSE: OFC), a specialty office real estate investment trust (REIT) that focuses primarily on serving the specialized requirements of U.S. Government and Defense Information Technology tenants, announced financial and operating results for the quarter ended September 30, 2011. Diluted earnings per share (EPS) was $0.03 for the quarter ended September 30, 2011 as compared to diluted EPS of $0.08 for the quarter ended September 30, 2010. Excluding a loss on the early retirement of debt and operating property acquisition costs, funds from operations per diluted share (FFOPS) for the third quarter of 2011 was $0.52, a 10% decrease from the $0.58 FFOPS reported in the third quarter of 2010.

“COPT modestly outperformed its expectations for the third quarter despite uncertainty caused by fears of a double dip recession, concerns over financial markets and continuing federal gridlock,” stated Randall M. Griffin, Chief Executive Officer of Corporate Office Properties Trust.  “During the quarter, we leased approximately 880,000 square feet of which 147,000 square feet was to the U.S. Government, our largest tenant.  Leasing dynamics were strong for the quarter with an 82% renewal rate and significantly lower lease capital costs,” he stated.

Operating Performance:

Portfolio Summary — At September 30, 2011, the Company’s wholly-owned portfolio of 246 operating office properties totaled 20.2 million square feet. The weighted average remaining lease term for the wholly-owned portfolio was 4.8 years and the average rental rate (including tenant reimbursements) was $26.20 per square foot. The Company’s wholly-owned portfolio was 88.0% occupied and 89.8% leased as of September 30, 2011.

Same Office Performance — The Company’s same office portfolio for the quarter ended September 30, 2011, represents 78% of the rentable square feet of its consolidated portfolio and consists of 187 properties. For the quarter ended September 30, 2011, the Company’s same office property cash NOI, excluding lease termination fees, increased 5% as compared to the second quarter of 2011 and was flat as compared to the quarter ended September 30, 2010.

Leasing — For the quarter ended September 30, 2011, 576,000 square feet were renewed equating to an 82% renewal rate, at an average committed cost of $5.39 per square foot. Total rent on renewed space increased 9.8%, as measured from the straight-line rent in effect preceding the renewal date, and decreased 2.3% on a cash basis. For renewed and retenanted space of 654,000 square feet,

total straight-line rent increased 9.3% and total rent on a cash basis decreased 2.1%. The average committed cost for renewed and retenanted space was $7.76 per square foot.

Investment Activity for the quarter ended September 30, 2011:

Construction — At September 30, 2011, the Company had properties totaling 1.2 million square feet under construction for a total projected cost of $279.4 million.

Acquisitions — The Company acquired one building located at 310 The Bridge Street in Cummings Research Park in Huntsville, Alabama with 138,000 square feet for $33.4 million.

Dispositions — As part of the Company’s Strategic Reallocation Plan, during the quarter, the Company sold one 36,000 square foot building located in the Hunt Valley Business Center in Hunt Valley, Maryland for $4.7 million and its Towson Portfolio consisting of 4 buildings in Towson, Maryland, totaling 179,000 square feet for $16 million.

Capital Transactions:

Effective September 1, 2011, the Company entered into a credit agreement providing for an unsecured revolving credit facility of $1 billion that matures on September 1, 2014, and may be extended by one year. Also effective September 1, 2011, the Company entered into a $400 million unsecured term loan agreement, with the right to borrow an additional $100 million. The unsecured term loan agreement matures on September 1, 2015, and may be extended by one year.

With the proceeds from the new revolving credit facility and term loan, the Company repaid and extinguished its previously existing $800 million revolving credit facility, its $225 million Revolving Construction Facility, and two variable rate secured loans totaling $270.3 million. Upon the early extinguishment of this debt, COPT recognized a loss of $1.7 million, representing unamortized issuance costs. The Company used proceeds from these transactions to complete the repurchase of $162.5 million aggregate principal amount of its 3.50% Exchangeable Senior Notes due 2026.

Balance Sheet and Financial Flexibility:

As of September 30, 2011, the Company had a total market capitalization of $4.3 billion, with $2.4 billion in debt outstanding, equating to a 56% debt-to-total market capitalization ratio. Also, the Company’s weighted average interest rate was 4.7% for the quarter ended September 30, 2011 and 70% of the Company’s debt was subject to fixed interest rates, including the effect of interest rate swaps.

For the third quarter 2011, the Company’s adjusted EBITDA to interest expense coverage ratio was 3.04x, and the adjusted EBITDA fixed charge coverage ratio was 2.57x. Adjusting for construction in progress, the Company’s adjusted debt-to-adjusted EBITDA ratio was 7.03x for the three months ended September 30, 2011.

Management Changes:

During the third quarter, the Company announced executive management changes including the retirement of Randall M. Griffin, CEO at the end of March 2012, and the appointment of his successor. Mr. Griffin will continue as a Trustee on COPT’s Board. Roger A. Waesche, Jr., was elected as CEO and a member of the Board of Trustees effective April 1, 2012. The addition of Stephen E. Budorick as Executive Vice President and Chief Operating Officer was also announced during the quarter. Mr. Budorick joined COPT most recently from Callahan Capital Partners, LLC.

He reports to Mr. Waesche and is responsible for leasing, asset management, property management, and government services.

2011 Guidance and Conference Call Information:

Management will discuss third quarter earnings results and any adjustments to earnings and FFO guidance for 2011, if applicable, on its conference call today at 11:00 a.m. Eastern Time, details of which are listed below:

Conference Call Date:	Thursday, October 27, 2011
Time:	11:00 a.m. Eastern Time
Telephone Number: (within the U.S.)	888-679-8033
Telephone Number: (outside the U.S.)	617-213-4846
Passcode:	52609055

Please use the following link to pre-register and view important information about this conference call. Pre-registering is not mandatory but is recommended as it will provide you immediate entry into the call and will facilitate the timely start of the conference. Pre-registration only takes a few moments and you may pre-register at anytime, including up to and after the call start time. To pre-register, please click on the below link:

https://www.theconferencingservice.com/prereg/key.process?key=PKA9BJCTN

You may also pre-register in the Investor Relations section of the Company’s website at www.copt.com. Alternatively, you may be placed into the call by an operator by calling the number provided above at least 5 to 10 minutes before the start of the call. A replay of this call will be available beginning Thursday, October 27 at 2:00 p.m. Eastern Time through Thursday, November 3 at midnight Eastern Time. To access the replay within in the United States, please call 888-286-8010 and use passcode 71355680. To access the replay outside the United States, please call 617-801-6888 and use passcode 71355680.

The conference call will also be available via live webcast in the Investor Relations section of the Company’s website at www.copt.com. A replay of the conference call will be immediately available via webcast in the Investor Relations section of the Company’s website.

Definitions:

Please refer to the information furnished with our Form 8-K or our website (www.copt.com) for definitions of certain terms used in this press release. Reconciliations of non-GAAP measures to the most directly comparable GAAP measures are included in the attached tables.

Company Information:

COPT is a specialty office REIT that focuses primarily on strategic customer relationships and specialized tenant requirements in the U.S. Government and Defense Information Technology sectors and Data Centers serving such sectors. The Company acquires, develops, manages and leases office and data center properties that are typically concentrated in large office parks primarily located adjacent to government demand drivers and/or in strong markets that we believe possess growth opportunities. As of September 30, 2011, the Company owned 266 office properties totaling 21.3 million rentable square feet, which includes 20 properties totaling 1.1

million square feet held through joint ventures. The Company’s portfolio primarily consists of technically sophisticated buildings in visually appealing settings that are environmentally sensitive, sustainable and meet unique customer requirements. COPT is an S&P MidCap 400 company and more information can be found at www.copt.com.

Forward-Looking Information:

This press release may contain “forward-looking” statements, as defined in Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, that are based on the Company’s current expectations, estimates and projections about future events and financial trends affecting the Company.  Forward-looking statements can be identified by the use of words such as “may,” “will,” “should,” “could,” “believe,” “anticipate,” “expect,” “estimate,” “plan” or other comparable terminology.  Forward-looking statements are inherently subject to risks and uncertainties, many of which the Company cannot predict with accuracy and some of which the Company might not even anticipate.  Accordingly, the Company can give no assurance that these expectations, estimates and projections will be achieved.  Future events and actual results may differ materially from those discussed in the forward-looking statements.

Important factors that may affect these expectations, estimates, and projections include, but are not limited to:

·general economic and business conditions, which will, among other things, affect office property demand and rents, tenant creditworthiness, interest rates and financing availability;

·adverse changes in the real estate markets including, among other things, increased competition with other companies;

·the Company’s ability to borrow on favorable terms;

·risks of real estate acquisition and development activities, including, among other things, risks that development projects may not be completed on schedule, that tenants may not take occupancy or pay rent or that development or operating costs may be greater than anticipated;

·risks of investing through joint venture structures, including risks that the Company’s joint venture partners may not fulfill their financial obligations as investors or may take actions that are inconsistent with the Company’s objectives;

·changes in our plans or views of market economic conditions or failure to obtain development rights, either of which could result in recognition of impairment losses;

·our ability to satisfy and operate effectively under Federal income tax rules relating to real estate investment trusts and partnerships;

·governmental actions and initiatives, including risks associated with the impact of a government shutdown such as a reduction in rental revenues or non-renewal of leases;

·the dilutive effect of issuing additional common shares; and

·environmental requirements.

The Company undertakes no obligation to update or supplement any forward-looking statements. For further information, please refer to the Company’s filings with the Securities and Exchange Commission, particularly the section entitled “Risk Factors” in Item 1A of the Company’s Annual Report on Form 10-K for the year ended December 31, 2010.

Reconciliations:

Reconciliations of non-GAAP measures to the most directly comparable GAAP measures are included in the tables, below:

Corporate Office Properties Trust

Summary Financial Data

(unaudited)

(Amounts in thousands, except per share data)

	Three Months Ended September 30,						Nine Months Ended September 30,
	2011			2010			2011			2010
Revenues
Real estate revenues	$	121,893		$	111,074		$	358,942		$	325,671
Construction contract and other service revenues	18,729			13,608			67,854			77,038
Total revenues	140,622			124,682			426,796			402,709
Expenses
Property operating expenses	47,655			43,013			141,287			128,331
Depreciation and amortization associated with real estate operations	35,719			29,503			97,720			84,368
Construction contract and other service expenses	18,171			13,347			65,698			75,148
Impairment losses	—			—			57,824			—
General and administrative expenses	6,154			6,079			19,251			17,905
Business development expenses	1,050			2,886			2,126			3,506
Total operating expenses	108,749			94,828			383,906			309,258
Operating income	31,873			29,854			42,890			93,451
Interest expense	(25,381		)	(26,174		)	(78,412		)	(74,042		)
Interest and other (loss) income	(242		)	395			3,682			1,942
Loss on early extinguishment of debt	(1,655		)	—			(1,680		)	—
Income (loss) from continuing operations before equity in (loss) income of unconsolidated entities and income taxes	4,595			4,075			(33,520		)	21,351
Equity in (loss) income of unconsolidated entities	(159		)	648			(223		)	371
Income tax benefit (expense)	457			(27		)	6,043			(75		)
Income (loss) from continuing operations	4,893			4,696			(27,700		)	21,647
Discontinued operations	2,577			1,753			(12,120		)	4,276
Income (loss) before gain on sales of real estate	7,470			6,449			(39,820		)	25,923
Gain on sales of real estate, net of income taxes	—			2,477			2,717			2,829
Net income (loss)	7,470			8,926			(37,103		)	28,752
Net (income) loss attributable to noncontrolling interests:
Common units in the Operating Partnership	(178		)	(363		)	3,188			(1,254		)
Preferred units in the Operating Partnership	(165		)	(165		)	(495		)	(495		)
Other consolidated entities	(561		)	434			(1,038		)	233
Net income (loss) attributable to COPT	6,566			8,832			(35,448		)	27,236
Preferred share dividends	(4,025		)	(4,025		)	(12,076		)	(12,076		)
Net income (loss) attributable to COPT common shareholders	$	2,541		$	4,807		$	(47,524	)	$	15,160
Earnings per share (“EPS”) computation:
Numerator for diluted EPS:
Net income (loss) attributable to common shareholders	$	2,541		$	4,807		$	(47,524	)	$	15,160
Dilutive effect of common units in the Operating Partnership	—			—			(3,188		)	—
Amount allocable to restricted shares	(262		)	(267		)	(781		)	(807		)
Numerator for diluted EPS	$	2,279		$	4,540		$	(51,493	)	$	14,353
Denominator:
Weighted average common shares - basic	71,312			58,656			68,718			58,333
Dilutive effect of common units in the Operating Partnership	—			—			4,371			—
Dilutive effect of share-based compensation awards	—			296			—			367
Weighted average common shares - diluted	71,312			58,952			73,089			58,700
Diluted EPS	$	0.03		$	0.08		$	(0.70	)	$	0.24

Corporate Office Properties Trust

Summary Financial Data

(unaudited)

(Amounts in thousands, except per share data and ratios)

	Three Months Ended September 30,						Nine Months Ended September 30,
	2011			2010			2011			2010
Net income (loss)	$	7,470		$	8,926		$	(37,103	)	$	28,752
Add: Real estate-related depreciation and amortization	36,032			30,745			101,101			87,896
Add: Depreciation and amortization on unconsolidated real estate entities	116			166			350			512
Less: Gain on sales of previously depreciated operating properties, net of income taxes	(1,299		)	(784		)	(1,449		)	(1,081		)
Funds from operations (“FFO”)	42,319			39,053			62,899			116,079
Noncontrolling interests - preferred units in the Operating Partnership	(165		)	(165		)	(495		)	(495		)
Noncontrolling interests - other consolidated entities	(561		)	434			(1,038		)	233
Preferred share dividends	(4,025		)	(4,025		)	(12,076		)	(12,076		)
Depreciation and amortization allocable to noncontrolling interests in other consolidated entities	(276		)	(666		)	(566		)	(1,245		)
Basic and diluted FFO allocable to restricted shares	(263		)	(353		)	(782		)	(1,078		)
Basic and diluted FFO available to common share and common unit holders (“Basic and diluted FFO”)	37,029			34,278			47,942			101,418
Operating property acquisition costs	77			2,664			152			2,954
Impairment losses	—			—			72,347			—
Income tax benefit from impairment losses	—			—			(4,598		)	—
Loss on early extinguishment of debt	1,995			—			2,020			—
Diluted FFO available to common share and common unit holders, as adjusted for comparability	39,101			36,942			117,863			104,372
Straight line rent adjustments	(2		)	1,267			(6,525		)	(2,552		)
Amortization of acquisition intangibles included in net operating income	212			(96		)	600			(460		)
Recurring capital expenditures	(11,599		)	(10,156		)	(40,856		)	(23,447		)
Share-based compensation, net of amounts capitalized	2,759			2,619			8,156			7,417
Amortization of deferred financing costs	1,629			1,554			5,090			4,175
Amortization of net debt discounts, net of amounts capitalized	1,184			1,496			4,046			3,772
Amortization of settled debt hedges	16			16			47			47
Diluted adjusted funds from operations available to common share and common unit holders (“Diluted AFFO”)	$	33,300		$	33,642		$	88,421		$	93,324
Recurring capital expenditures on properties included in disposition plans	2,889			—			13,896			—
Diluted AFFO, as adjusted for recurring capital expenditures on properties included in disposition plans	$	36,189		$	33,642		$	102,317		$	93,324
Weighted average shares
Weighted average common shares	71,312			58,656			68,718			58,333
Conversion of weighted average common units	4,336			4,453			4,371			4,674
Weighted average common shares/units - basic FFO per share	75,648			63,109			73,089			63,007
Dilutive effect of share-based compensation awards	52			296			147			367
Weighted average common shares/units - diluted FFO per share	75,700			63,405			73,236			63,374
Diluted FFO per share	$	0.49		$	0.54		$	0.65		$	1.60
Diluted FFO per share, as adjusted for comparability	$	0.52		$	0.58		$	1.61		$	1.65
Dividends/distributions per common share/unit	$	0.4125		$	0.4125		$	1.2375		$	1.1975
Payout ratios
Diluted FFO, as adjusted for comparability	80.5		%	71.3		%	78.4		%	73.2		%
Diluted AFFO	94.5		%	78.3		%	104.5		%	81.8		%
Diluted AFFO, as adjusted for recurring capital expenditures on properties included in disposition plans	87.0		%	78.3		%	90.3		%	81.8		%
Adjusted EBITDA interest coverage ratio	3.04x			2.84x			3.01x			2.88x
Adjusted EBITDA fixed charge coverage ratio	2.57x			2.41x			2.55x			2.43x
Debt to Adjusted EBITDA ratio (1)	8.73x			9.21x			N/A			N/A
Adjusted debt to Adjusted EBITDA ratio (2)	7.03x			7.93x			N/A			N/A
Reconciliation of denominators for diluted EPS and diluted FFO per share
Denominator for diluted EPS	71,312			58,952			73,089			58,700
Weighted average common units	4,336			4,453			—			4,674
Anti-dilutive EPS effect of share-based compensation awards	52			—			147			—
Denominator for diluted FFO per share	75,700			63,405			73,236			63,374

(1)	Represents debt divided by Adjusted EBITDA for the three month period multiplied by four.
(2)	Represents debt adjusted to subtract construction in progress as of period end divided by Adjusted EBITDA for the three month period multiplied by four.

Corporate Office Properties Trust

Summary Financial Data

(unaudited)

(Dollars and shares in thousands, except per share data)

	September 30,			December 31,
	2011			2010
Balance Sheet Data (in thousands) (as of period end)
Properties, net of accumulated depreciation	$	3,469,217		$	3,445,455
Total assets	3,965,392			3,844,517
Debt, net	2,420,073			2,323,681
Total liabilities	2,657,769			2,521,379
Beneficiaries’ equity	1,307,623			1,323,138
Debt to undepreciated book value of real estate assets	57.6		%	57.2		%
Debt to total market capitalization	56.2		%	46.1		%
Property Data (wholly owned office properties) (as of period end)
Number of operating properties owned	246			252
Total net rentable square feet owned (in thousands)	20,205			19,990
Occupancy	88.0		%	88.2		%
Reconciliation of denominator for debt to total assets to denominator for debt to undepreciated book value of real estate assets
Denominator for debt to total assets	$	3,965,392		$	3,844,517
Assets other than assets included in properties, net and assets held for sale	(423,408		)	(399,062		)
Accumulated depreciation on real estate assets	553,306			503,032
Accumulated depreciation included in assets held for sale	6,791			—
Intangible assets on real estate acquisitions, net	97,954			113,735
Non real estate assets included in assets held for sale	(1,946		)	—
Denominator for debt to undepreciated book value of real estate assets	$	4,198,089		$	4,062,222

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2011			2010			2011			2010
Reconciliation of tenant improvements and incentives, capital improvements and leasing costs for operating properties to recurring capital expenditures
Total tenant improvements and incentives on operating properties	$	7,082		$	7,789		$	31,468		$	16,490
Total capital improvements on operating properties	5,380			1,717			9,796			4,111
Total leasing costs on operating properties	4,223			2,004			10,347			4,692
Less: Nonrecurring tenant improvements and incentives on operating properties	(1,826		)	(1,067		)	(5,149		)	(1,280		)
Less: Nonrecurring capital improvements on operating properties	(3,046		)	(171		)	(4,476		)	(524		)
Less: Nonrecurring leasing costs for operating properties	(234		)	(120		)	(1,197		)	(69		)
Add: Recurring capital expenditures on operating properties held through joint ventures	20			4			67			27
Recurring capital expenditures	$	11,599		$	10,156		$	40,856		$	23,447

Corporate Office Properties Trust

Summary Financial Data

(unaudited)

(Dollars in thousands)

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2011			2010			2011			2010
Reconciliation of common share dividends to dividends and distributions for payout ratios
Common share dividends	$	29,688		$	24,494		$	87,024		$	70,913
Common unit distributions	1,781			1,834			5,398			5,450
Dividends and distributions for payout ratios	$	31,469		$	26,328		$	92,422		$	76,363
Reconciliation of FFO to FFO, as adjusted for comparability
FFO	$	42,319		$	39,053		$	62,899		$	116,079
Impairment losses, net of related tax benefit	—			—			67,749			—
Operating property acquisition costs	77			2,664			152			2,954
Loss on early extinguishment of debt	1,995			—			2,020			—
FFO, as adjusted for comparability	$	44,391		$	41,717		$	132,820		$	119,033
Reconciliation of GAAP net income (loss) to adjusted earnings before interest, income taxes, depreciation and amortization (“Adjusted EBITDA”)
Net income (loss)	$	7,470		$	8,926		$	(37,103	)	$	28,752
Interest expense on continuing operations	25,381			26,174			78,412			74,042
Interest expense on discontinued operations	248			452			975			1,208
Income tax (benefit) expense	(457		)	27			(6,043		)	86
Real estate-related depreciation and amortization	36,032			30,745			101,101			87,896
Depreciation of furniture, fixtures and equipment	614			652			1,862			1,934
Impairment losses	—			—			72,347			—
Adjusted EBITDA	$	69,288		$	66,976		$	211,551		$	193,918
Reconciliation of interest expense from continuing operations to the denominators for interest coverage-Adjusted EBITDA and fixed charge coverage-Adjusted EBITDA
Interest expense from continuing operations	$	25,381		$	26,174		$	78,412		$	74,042
Interest expense from discontinued operations	248			452			975			1,208
Less: Amortization of deferred financing costs	(1,629		)	(1,554		)	(5,090		)	(4,175		)
Less: Amortization of net debt discount, net of amounts capitalized	(1,184		)	(1,496		)	(4,046		)	(3,772		)
Denominator for interest coverage-Adjusted EBITDA	22,816			23,576			70,251			67,303
Preferred share dividends	4,025			4,025			12,076			12,076
Preferred unit distributions	165			165			495			495
Denominator for fixed charge coverage-Adjusted EBITDA	$	27,006		$	27,766		$	82,822		$	79,874
Reconciliation of same office property net operating income to same office property cash net operating income and same office property cash net operating income, excluding gross lease termination fees
Same office property net operating income	$	61,853		$	61,872		$	182,640		$	185,412
Add (less): Straight-line rent adjustments	1,882			1,970			(2,549		)	(1,768		)
Less: Amortization of deferred market rental revenue	(197		)	(281		)	(631		)	(943		)
Add: Amortization of above-market cost arrangements	329			337			986			1,011
Same office property cash net operating income	$	63,867		$	63,898		$	180,446		$	183,712
Less: Lease termination fees, gross	(130		)	(109		)	(313		)	(1,175		)
Same office property cash net operating income, excluding gross lease termination fees	$	63,737		$	63,789		$	180,133		$	182,537
Reconciliation of debt, net to denominator for adjusted debt to Adjusted EBITDA ratio
Debt, net	$	2,420,073		$	2,468,419
Less: Properties under construction and development, excluding associated land costs	(447,969		)	(344,924		)
Less: Properties under construction and development on assets held for sale, excluding associated land costs	(22,936		)	—
Denominator for adjusted debt to Adjusted EBITDA ratio	$	1,949,168		$	2,123,495

Third Quarter 2011

Summary Description

The Company — Corporate Office Properties Trust (the “Company” or “COPT”) is a self-managed, specialty office real estate investment trust (“REIT”). As of September 30, 2011, COPT derived 59% of its annualized rental revenue from wholly owned properties occupied primarily by tenants in the U.S. Government and/or defense information technology (“Defense IT”) sectors and data centers serving such sectors and 83% of the Company’s square footage was located in the Greater Washington/Baltimore region. At September 30, 2011, COPT’s wholly-owned portfolio of 246 office properties encompassed 20.2 million square feet and was 89.8% leased. As of the same date, COPT also owns one wholesale data center that was 17% leased.

Corporate Strategy — Through acquiring and developing, COPT has assembled a portfolio of Class-A office parks located adjacent to knowledge-based defense installations (rather than weapons production-oriented bases) that are executing programs deemed critical to the nation’s current and future security. COPT also owns dedicated data centers that serve the specialized requirements of our government and Defense IT tenants and a wholesale data center.

Management:	Investor Relations:
Randall M. Griffin, CEO	Stephanie M. Krewson, VP of IR
Roger A. Waesche, Jr., President	443-285-5453, stephanie.krewson@copt.com
Stephen E. Budorick, EVP & COO
Stephen E. Riffee, EVP & CFO	Michelle Layne, IR Specialist
Wayne H. Lingafelter, EVP, Development & Construction	443-285-5452, michelle.layne@copt.com

Disclosure Statement — This supplemental package contains forward-looking statements within the meaning of the Federal securities laws. Forward-looking statements can be identified by the use of words such as “may,” “will,” “should,” “could,” “believe,” “anticipate,” “expect,” “estimate,” “plan” or other comparable terminology.  Forward-looking statements are inherently subject to risks and uncertainties, many of which we cannot predict with accuracy and some of which we might not even anticipate.  Although we believe that the expectations, estimates and projections reflected in such forward-looking statements are based on reasonable assumptions at the time made, we can give no assurance that these expectations, estimates and projections will be achieved.  Future events and actual results may differ materially from those discussed in the forward-looking statements.  Important factors that may affect these expectations, estimates and projections include, but are not limited to: general economic and business conditions, which will, among other things, affect office property demand and rents, tenant creditworthiness, interest rates and financing availability; adverse changes in the real estate markets including, among other things, increased competition with other companies; our ability to borrow on favorable terms; risks of real estate acquisition and development activities, including, among other things, risks that development projects may not be completed on schedule, that tenants may not take occupancy or pay rent or that development and operating costs may be greater than anticipated; risks of investing through joint venture structures, including risks that our joint venture partners may not fulfill their financial obligations as investors or may take actions that are inconsistent with our objectives; changes in our plans for properties or views of market economic conditions or failure to obtain development rights, either of which could result in recognition of impairment losses; our ability to satisfy and operate effectively under Federal income tax rules relating to real estate investment trusts and partnerships; governmental actions and initiatives; and environmental requirements.  We undertake no obligation to update or supplement any forward-looking statements.  For further information, please refer to our filings with the Securities and Exchange Commission, particularly the section entitled “Risk Factors” in Item 1A of our Annual Report on Form 10-K for the year ended December 31, 2010.

1

Third Quarter 2011

Research Coverage

EQUITY RESEARCH COVERAGE:

Firm	Analyst	Phone	Email
Bank of America Merrill Lynch	Jamie Feldman	646-855-5808	james.feldman@baml.com
BMO Capital Markets	Richard Anderson	212-885-4180	richard.anderson@bmo.com
Citigroup Global Markets	Michael Bilerman	212-816-1383	michael.bilerman@citi.com
Cowen and Company	Michael Gorman	646-562-1381	michael.gorman@cowen.com
Friedman Billings Ramsey & Co.	Sri Nagarajan	646-885-5429	snagarajan@fbr.com
Green Street Advisors	Michael Knott	949-640-8780	mknott@greenstreetadvisors.com
ISI Group	Steve Sakwa	212-446-9462	ssakwa@isigrp.com
Jeffries & Co.	Steve Benyik	212-707-6348	sbenyik@jefferies.com
JP Morgan	Anthony Paolone	212-622-6682	anthony.paolone@jpmorgan.com
Keefe, Bruyette & Woods	Sheila McGrath	212-887-7793	smcgrath@kbw.com
KeyBanc Capital Markets	Jordan Sadler	917-368-2280	jsadler@keybanccm.com
Macquarie Securities	Rob Stevenson	212-231-8068	rob.stevenson@macquarie.com
Raymond James	Bill Crow	727-567-2594	bill.crow@raymondjames.com
RBC Capital Markets	Dave Rodgers	440-715-2647	dave.rodgers@rbccm.com
Robert W. Baird & Co., Inc.	Chris Lucas	703-821-5780	crlucas@rwbaird.com
Stifel, Nicolaus & Company, Inc.	John Guinee	443-224-1307	jwguinee@stifel.com
Wells Fargo Securities	Brendan Maiorana	443-263-6516	brendan.maiorana@wachovia.com

With the exception of Green Street Advisors, the above-listed firms are those whose analysts publish research material on the Company and whose estimates of our FFO per share can be tracked through Thomson’s First Call Corporation. Any opinions, estimates, or forecasts the above analysts make regarding COPT’s future performance are their own and do not represent the views, estimates, or forecasts of COPT’s management.

2

Third Quarter 2011

Selected Financial Summary Data

(in thousands, except per share data)

	Three Months Ended															Nine Months Ended
	9/30/11			6/30/11			3/31/11			12/31/10			9/30/10			9/30/11			9/30/10
SUMMARY OF RESULTS
NOI	$	76,417		$	75,352		$	71,536		$	76,694		$	70,724		$	223,305		$	205,271
Adjusted EBITDA	$	69,288		$	73,058		$	69,205		$	79,652		$	66,976		$	211,551		$	193,918
Net income (loss) attributable to COPT common shareholders	$	2,541		$	(28,250	)	$	(21,815	)	$	11,498		$	4,807		$	(47,524	)	$	15,160
FFO - per NAREIT	$	42,319		$	6,007		$	14,573		$	52,222		$	39,053		$	62,899		$	116,079
FFO - as adjusted for comparability	$	44,391		$	46,091		$	42,338		$	52,692		$	41,717		$	132,820		$	119,033
Basic and diluted FFO available to common share and common unit holders	$	37,029		$	1,415		$	9,498		$	47,227		$	34,278		$	47,942		$	101,418
Diluted AFFO available to common share and common unit holders	$	33,300		$	30,021		$	25,100		$	35,010		$	33,642		$	88,421		$	93,324
Per share - diluted:
EPS	$	0.03		$	(0.42	)	$	(0.33	)	$	0.18		$	0.08		$	(0.70	)	$	0.24
FFO - NAREIT	$	0.49		$	0.02		$	0.13		$	0.69		$	0.54		$	0.65		$	1.60
FFO - as adjusted for comparability	$	0.52		$	0.57		$	0.52		$	0.70		$	0.58		$	1.61		$	1.65
Dividend per common share	$	0.4125		$	0.4125		$	0.4125		$	0.4125		$	0.4125		$	1.2375		$	1.1975
Payout ratios:
Diluted FFO - as adjusted for comparability	80.5		%	75.8		%	79.2		%	61.7		%	71.3		%	78.4		%	73.2		%
Diluted AFFO	94.5		%	104.7		%	117.6		%	84.0		%	78.3		%	104.5		%	81.8		%
Diluted AFFO, as adjusted for recurring capital expenditures of properties included in disposition plans	87.0		%	90.7		%	93.8		%	84.0		%	78.3		%	90.3		%	81.8		%
CAPITALIZATION
Debt, net	$	2,420,073		$	2,299,416		$	2,396,795		$	2,323,681		$	2,468,419
Debt to Total Market Capitalization	56.2		%	47.0		%	46.0		%	46.1		%	48.6		%
Debt to Undepreciated Book Value of Real Estate Assets	57.6		%	56.0		%	58.4		%	57.2		%	62.5		%
Adjusted EBITDA fixed charge coverage ratio	2.6		x	2.6		x	2.5		x	2.8		x	2.4		x
Adjusted Debt to Adjusted EBITDA ratio	7.0		x	6.4		x	7.2		x	6.1		x	7.9		x
OTHER
Revenue from early termination of leases	$	103		$	196		$	146		$	2,014		$	182		$	445		$	1,371
Capitalized interest costs	$	4,458		$	4,308		$	4,341		$	4,520		$	3,861		$	13,107		$	12,005

3

Third Quarter 2011

Selected Financial Summary Data

(in thousands, except per share data)

	9/30/11			6/30/11			3/31/11			12/31/10			9/30/10
PORTFOLIO
Properties, gross (excluding accumulated depreciation)
Wholly-owned	$	3,975,483		$	3,887,684		$	3,879,847		$	3,833,624		$	3,715,452
+ Consolidated JV (1)	124,109			119,584			115,749			114,863			112,916
Consolidated properties	$	4,099,592		$	4,007,268		$	3,995,596		$	3,948,487		$	3,828,368
# of Operating Office Properties
Wholly-owned	246			249			252			252			249
+ Consolidated JV	4			4			4			4			4
Consolidated properties	250			253			256			256			253
% Occupied
Wholly-owned	88.0		%	87.3		%	87.0		%	88.2		%	87.4		%
+ Consolidated JV	60.0		%	58.9		%	61.5		%	61.5		%	61.5		%
Consolidated properties	87.4		%	86.6		%	86.4		%	87.6		%	86.8		%
% Leased
Wholly-owned	89.8		%	89.4		%	89.2		%	89.5		%	88.7		%
+ Consolidated JV	63.6		%	60.1		%	62.8		%	62.7		%	62.7		%
Consolidated properties	89.2		%	88.7		%	88.6		%	88.9		%	88.1		%
Square Feet of office properties (in thousands)
Wholly-owned	20,205			20,244			20,183			19,990			19,929
+ Consolidated JV Square Footage	443			442			442			442			442
Consolidated Square Footage	20,647			20,686			20,625			20,432			20,371
% Square Feet in Greater Washington, DC/Baltimore Region from wholly owned properties	83.4		%	84.1		%	84.4		%	84.2		%	84.2		%
% of Wholly Owned Office Annualized Rental Revenue from “Strategic Tenant Properties”	59.3		%	59.1		%	58.8		%	58.7		%	56.5		%

(1) Includes the total assets recorded on the books of the consolidated joint venture plus any outside investment basis related to the applicable joint venture and related joint ventures (formed and to be formed).

4

Third Quarter 2011

Quarterly Consolidated Balance Sheets

(dollars in thousands)

	9/30/11			6/30/11			3/31/11			12/31/10			9/30/10
Assets
Properties, net
Operating properties	$	3,325,609		$	3,269,049		$	3,345,921		$	3,305,805		$	3,241,507
Land - development	248,945			248,647			253,505			256,487			241,937
Properties under construction and development, excluding associated land costs	447,969			407,674			396,170			386,195			344,924
Less: accumulated depreciation	(553,306		)	(527,616		)	(526,825		)	(503,032		)	(479,218		)
Total properties, net	3,469,217			3,397,754			3,468,771			3,445,455			3,349,150
Assets held for sale	72,767			77,172			—			—			—
Cash and cash equivalents	11,504			11,703			12,606			10,102			11,733
Restricted cash and marketable securities	39,232			22,909			24,094			22,582			21,095
Accounts receivable, net	20,991			13,083			19,765			18,938			18,906
Deferred rent receivable	87,148			84,457			82,901			79,160			76,833
Intangible assets on real estate acquisitions, net	97,954			99,374			106,444			113,735			123,307
Deferred leasing and financing costs, net	70,791			60,199			60,479			60,649			56,568
Prepaid expenses and other assets	95,788			101,579			90,749			93,896			79,780
Total assets	$	3,965,392		$	3,868,230		$	3,865,809		$	3,844,517		$	3,737,372
Liabilities and equity
Liabilities:
Debt, net	$	2,420,073		$	2,299,416		$	2,396,795		$	2,323,681		$	2,468,419
Accounts payable and accrued expenses	114,834			115,154			103,043			99,699			88,461
Rents received in advance and security deposits	28,241			26,779			29,427			31,603			26,919
Dividends and distributions payable	35,029			35,021			33,048			32,986			29,899
Deferred revenue associated with operating leases	15,621			12,883			13,897			14,802			15,790
Distributions received in excess of investment in unconsolidated real estate joint venture	5,953			5,841			5,686			5,545			5,458
Interest rate derivatives	30,629			10,020			3,564			4,226			4,943
Other liabilities	7,389			9,744			8,691			8,837			7,755
Total liabilities	2,657,769			2,514,858			2,594,151			2,521,379			2,647,644
Commitments and contingencies	—			—			—			—			—
Equity:
COPT’s shareholders’ equity:
Preferred shares (aggregate liquidation preference of $216,333)	81			81			81			81			81
Common shares	720			719			671			669			594
Additional paid-in capital	1,663,850			1,657,536			1,511,638			1,511,844			1,271,363
Cumulative distributions in excess of net income	(416,342		)	(389,195		)	(331,313		)	(281,794		)	(265,695		)
Accumulated other comprehensive loss	(28,618		)	(9,624		)	(3,197		)	(4,163		)	(4,861		)
Total COPT’s shareholders’ equity	1,219,691			1,259,517			1,177,880			1,226,637			1,001,482
Noncontrolling interests in subsidiaries
Common units in the Operating Partnership	60,583			66,482			66,016			69,337			61,867
Preferred units in the Operating Partnership	8,800			8,800			8,800			8,800			8,800
Other consolidated entities	18,549			18,573			18,962			18,364			17,579
Total noncontrolling interests in subsidiaries	87,932			93,855			93,778			96,501			88,246
Total equity	1,307,623			1,353,372			1,271,658			1,323,138			1,089,728
Total liabilities and equity	$	3,965,392		$	3,868,230		$	3,865,809		$	3,844,517		$	3,737,372

5

Third Quarter 2011

Consolidated Statements of Operations

(in thousands, except per share data)

	Three Months Ended															Nine Months Ended
	9/30/11			6/30/11			3/31/11			12/31/10			9/30/10			9/30/11			9/30/10
Revenues
Rental revenue	$	99,068		$	97,890		$	96,589		$	96,389		$	90,264		$	293,547		$	266,334
Tenant recoveries and other real estate operations revenue	22,825			19,795			22,775			22,850			20,810			65,395			59,337
Construction contract and other service revenues	18,729			28,097			21,028			27,637			13,608			67,854			77,038
Total revenues	140,622			145,782			140,392			146,876			124,682			426,796			402,709
Expenses
Property operating expenses	47,655			44,366			49,266			45,751			43,013			141,287			128,331
Depreciation and amortization associated with real estate operations	35,719			31,059			30,942			33,558			29,503			97,720			84,368
Construction contract and other service expenses	18,171			26,909			20,618			27,154			13,347			65,698			75,148
Impairment losses	—			30,082			27,742			—			—			57,824			—
General and administrative expenses	6,154			6,320			6,777			6,103			6,079			19,251			17,905
Business development expenses	1,050			588			488			691			2,886			2,126			3,506
Total operating expenses	108,749			139,324			135,833			113,257			94,828			383,906			309,258
Operating income	31,873			6,458			4,559			33,619			29,854			42,890			93,451
Interest expense	(25,381		)	(26,500		)	(26,531		)	(26,517		)	(26,174		)	(78,412		)	(74,042		)
Interest and other (loss) income	(242		)	2,756			1,168			7,626			395			3,682			1,942
Loss on early extinguishment of debt	(1,655		)	(25		)	—			—			—			(1,680		)	—
Income (loss) from continuing operations before equity in (loss) income of unconsolidated entities and income taxes	4,595			(17,311		)	(20,804		)	14,728			4,075			(33,520		)	21,351
Equity in (loss) income of unconsolidated entities	(159		)	(94		)	30			1,005			648			(223		)	371
Income tax benefit (expense)	457			5,042			544			(33		)	(27		)	6,043			(75		)
Income (loss) from continuing operations	4,893			(12,363		)	(20,230		)	15,700			4,696			(27,700		)	21,647
Discontinued operations	2,577			(13,660		)	(1,037		)	1,052			1,753			(12,120		)	4,276
Income (loss) before gain on sales of real estate	7,470			(26,023		)	(21,267		)	16,752			6,449			(39,820		)	25,923
Gain on sales of real estate, net of income taxes	—			16			2,701			—			2,477			2,717			2,829
Net income (loss)	7,470			(26,007		)	(18,566		)	16,752			8,926			(37,103		)	28,752
Net (income) loss attributable to noncontrolling interests
Common units in the Operating Partnership	(178		)	1,887			1,479			(862		)	(363		)	3,188			(1,254		)
Preferred units in the Operating Partnership	(165		)	(165		)	(165		)	(165		)	(165		)	(495		)	(495		)
Other consolidated entities	(561		)	61			(538		)	(201		)	434			(1,038		)	233
Net income (loss) attributable to COPT	6,566			(24,224		)	(17,790		)	15,524			8,832			(35,448		)	27,236
Preferred share dividends	(4,025		)	(4,026		)	(4,025		)	(4,026		)	(4,025		)	(12,076		)	(12,076		)
Net income (loss) attributable to COPT common shareholders	$	2,541		$	(28,250	)	$	(21,815	)	$	11,498		$	4,807		$	(47,524	)	$	15,160
For diluted EPS computations:
Numerator for diluted EPS
Net income (loss) attributable to common shareholders	$	2,541		$	(28,250	)	$	(21,815	)	$	11,498		$	4,807		$	(47,524	)	$	15,160
Dilutive effect of common units in the Operating Partnership	—			(1,887		)	(1,479		)	—			—			(3,188		)	—
Amount allocable to restricted shares	(262		)	(237		)	(282		)	(264		)	(267		)	(781		)	(807		)
Numerator for diluted EPS	$	2,279		$	(30,374	)	$	(23,576	)	$	11,234		$	4,540		$	(51,493	)	$	14,353
Denominator:
Weighted average common shares - basic	71,312			68,446			66,340			63,404			58,656			68,718			58,333
Dilutive effect of common units in the Operating Partnership	—			4,382			4,396			—			—			4,371			—
Dilutive effect of share-based compensation awards	—			—			—			236			296			—			367
Weighted average common shares - diluted	71,312			72,828			70,736			63,640			58,952			73,089			58,700
Diluted EPS	$	0.03		$	(0.42	)	$	(0.33	)	$	0.18		$	0.08		$	(0.70	)	$	0.24

6

Third Quarter 2011

Consolidated Reconciliations of FFO and AFFO

(in thousands, except per share data)

	Three Months Ended															Nine Months Ended
	9/30/11			6/30/11			3/31/11			12/31/10			9/30/10			9/30/11			9/30/10
Net operating income	$	76,417		$	75,352		$	71,536		$	76,694		$	70,724		$	223,305		$	205,271
General and administrative expenses	(6,154		)	(6,320		)	(6,777		)	(6,103		)	(6,079		)	(19,251		)	(17,905		)
Business development expenses	(1,050		)	(588		)	(488		)	(691		)	(2,886		)	(2,126		)	(3,506		)
Income from construction contracts and other service operations	558			1,188			410			483			261			2,156			1,890
Impairment losses	—			(44,605		)	(27,742		)	—			—			(72,347		)	—
Equity in (loss) income of unconsolidated entities	(159		)	(94		)	30			1,005			648			(223		)	371
Depreciation and amortization on unconsolidated real estate entities	116			115			119			119			166			350			512
Interest and other income	(242		)	2,756			1,168			7,626			395			3,682			1,942
Loss on early extinguishment of debt on continuing and discontinued operations	(1,995		)	(25		)	—			—			—			(2,020		)	—
Gain on sales of real estate, net of income taxes	—			16			2,701			—			2,477			2,717			2,829
Total interest expense	(25,629		)	(26,830		)	(26,928		)	(26,878		)	(26,626		)	(79,387		)	(75,250		)
Income tax benefit (expense)	457			5,042			544			(33		)	(27		)	6,043			(75		)
FFO - per NAREIT	42,319			6,007			14,573			52,222			39,053			62,899			116,079
Preferred share dividends	(4,025		)	(4,026		)	(4,025		)	(4,026		)	(4,025		)	(12,076		)	(12,076		)
Noncontrolling interests - preferred units in the Operating Partnership	(165		)	(165		)	(165		)	(165		)	(165		)	(495		)	(495		)
Noncontrolling interests - other consolidated entities (1)	(561		)	61			(538		)	(201		)	434			(1,038		)	233
Depreciation and amortization allocable to noncontrolling interests in other consolidated entities (1)	(276		)	(225		)	(65		)	(157		)	(666		)	(566		)	(1,245		)
Basic and diluted FFO allocable to restricted shares	(263		)	(237		)	(282		)	(446		)	(353		)	(782		)	(1,078		)
Basic and diluted FFO available to common share and common unit holders	$	37,029		$	1,415		$	9,498		$	47,227		$	34,278		$	47,942		$	101,418
FFO - per NAREIT	$	42,319		$	6,007		$	14,573		$	52,222		$	39,053		$	62,899		$	116,079
Depreciation and amortization	(36,032		)	(32,049		)	(33,020		)	(35,347		)	(30,745		)	(101,101		)	(87,896		)
Gain on sales of previously depreciated operating properties, net of income taxes	1,299			150			—			(4		)	784			1,449			1,081
Depreciation and amortization on unconsolidated real estate entities	(116		)	(115		)	(119		)	(119		)	(166		)	(350		)	(512		)
Net income (loss)	7,470			(26,007		)	(18,566		)	16,752			8,926			(37,103		)	28,752
Noncontrolling interests - common units in the Operating Partnership	(178		)	1,887			1,479			(862		)	(363		)	3,188			(1,254		)
Noncontrolling interests - preferred units in the Operating Partnership	(165		)	(165		)	(165		)	(165		)	(165		)	(495		)	(495		)
Noncontrolling interests - other consolidated entities	(561		)	61			(538		)	(201		)	434			(1,038		)	233
Net income (loss) attributable to COPT	$	6,566		$	(24,224	)	$	(17,790	)	$	15,524		$	8,832		$	(35,448	)	$	27,236
Diluted FFO available to common share and common unit holders	$	37,029		$	1,415		$	9,498		$	47,227		$	34,278		$	47,942		$	101,418
Operating property acquisition costs	77			52			23			470			2,664			152			2,954
Impairment losses, net of related tax benefit	—			40,007			27,742			—			—			67,749			—
Loss on early extinguishment of debt on continuing and discontinued operations	1,995			25			—			—			—			2,020			—
Diluted FFO available to common share and common unit holders, as adjusted for comparability	39,101			41,499			37,263			47,697			36,942			117,863			104,372
Straight line rent adjustments	(2		)	(2,611		)	(3,912		)	(2,047		)	1,267			(6,525		)	(2,552		)
Amortization of acquisition intangibles included in NOI	212			227			161			(231		)	(96		)	600			(460		)
Recurring capital expenditures	(11,599		)	(14,913		)	(14,344		)	(15,960		)	(10,156		)	(40,856		)	(23,447		)
Share-based compensation, net of amounts capitalized	2,759			2,638			2,759			2,638			2,619			8,156			7,417
Amortization of deferred financing costs	1,629			1,702			1,759			1,696			1,554			5,090			4,175
Amortization of net debt discounts, net of amounts capitalized	1,184			1,464			1,398			1,202			1,496			4,046			3,772
Amortization of settled debt hedges	16			15			16			15			16			47			47
Diluted AFFO available to common share and common unit holders (“diluted AFFO”)	$	33,300		$	30,021		$	25,100		$	35,010		$	33,642		$	88,421		$	93,324
Recurring capital expenditures of properties included in disposition plans	2,889			4,639			6,368			—			—			13,896			—
Diluted AFFO, as adjusted for recurring capital expenditures of properties included in disposition plans	$	36,189		$	34,660		$	31,468		$	35,010		$	33,642		$	102,317		$	93,324
FFO - per NAREIT	$	42,319		$	6,007		$	14,573		$	52,222		$	39,053		$	62,899		$	116,079
Operating property acquisition costs	77			52			23			470			2,664			152			2,954
Impairment losses, net of related tax benefit	—			40,007			27,742			—			—			67,749			—
Loss on early extinguishment of debt on continuing and discontinued operations	1,995			25			—			—			—			2,020			—
FFO- as adjusted for comparability	$	44,391		$	46,091		$	42,338		$	52,692		$	41,717		$	132,820		$	119,033

(1) The sum of these two lines equates to our consolidated joint venture partners’ share of FFO.

7

Third Quarter 2011

Summary of Wholly Owned Operating Office Properties by Region - September 30, 2011

	Operational						Under Construction/ Redevelopment
Property Region and Business Park/Submarket	# of Properties	Total Square Feet	Occupancy %		Leased  %		# of Properties	Total Square Feet
Baltimore/Washington Corridor:
National Business Park	25	2,941,863	100	%	100	%	3	284,041
Columbia Gateway	28	2,221,845	88	%	88	%	—	—
Airport Square/bwtech	26	1,942,489	85	%	85	%	—	—
Columbia South	18	813,404	88	%	92	%	1	89,295
Commons/Parkway	11	506,579	77	%	79	%	—	—
Other	1	155,000	100	%	100	%	—	—
Subtotal	109	8,581,180	91	%	91	%	4	373,336
Northern Virginia:
Westfields Corporate Center	9	1,437,494	85	%	86	%	—	—
Tysons Corner/ Merrifield	4	650,228	96	%	96	%	1	140,530
Herndon	2	548,334	85	%	93	%	—	—
Dulles Tech	2	165,490	91	%	91	%	—	—
Patriot Ridge	—	—	0	%	0	%	1	236,685
Subtotal	17	2,801,546	88	%	90	%	2	377,215
Suburban Maryland	5	709,390	71	%	87	%	—	—
Washington, DC- Capital Riverfront	2	362,209	97	%	97	%	—	—
St. Mary’s & King George Counties
St. Mary’s County	12	614,543	85	%	85	%	1	82,842
King George County	6	206,149	94	%	96	%	—	—
Subtotal	18	820,692	87	%	88	%	1	82,842
Greater Baltimore:
White Marsh	35	1,577,401	80	%	83	%	—	—
Route 83 Corridor	10	1,043,947	85	%	89	%	—	—
Canton Crossing-Baltimore City	1	481,277	93	%	94	%	—	—
Baltimore County Westside	13	365,407	79	%	79	%	—	—
Harford County-North Gate Business Park	2	104,743	100	%	100	%	2	180,141
Subtotal	61	3,572,775	84	%	86	%	2	180,141
Colorado Springs:
Colorado Springs East	11	724,064	75	%	76	%	—	—
I-25 North Corridor	7	522,808	67	%	67	%	—	—
Colorado Springs Northwest	3	322,464	96	%	97	%	—	—
Subtotal	21	1,569,336	77	%	77	%	—	—
San Antonio, Texas	8	915,429	100	%	100	%	1	94,961
Greater Philadelphia, Pennsylvania	2	437,718	90	%	100	%	1	113,800
Other	3	434,308	100	%	100	%	—	—
Total	246	20,204,583	88	%	90	%	11	1,222,295

8

Third Quarter 2011

Property Occupancy Rates by Region by Quarter

(wholly owned office properties)

	Baltimore /								St. Mary’s &
	Washington		Northern		Greater		Suburban		King George		Colorado		San		Greater		Washington, DC-				Total
	Corridor		Virginia		Baltimore		Maryland		Counties		Springs		Antonio		Philadelphia		Capitol Riverfront		Other		Portfolio
September 30, 2011
Number of Buildings	109		17		61		5		18		21		8		2		2		3		246
Rentable Square Feet	8,581,180		2,801,546		3,572,775		709,390		820,692		1,569,336		915,429		437,718		362,209		434,308		20,204,583
Occupied %	90.8	%	88.2	%	83.8	%	71.0	%	87.4	%	76.7	%	100.0	%	89.9	%	97.4	%	100.0	%	88.0	%
Leased %	91.4	%	90.2	%	86.1	%	87.1	%	87.8	%	77.3	%	100.0	%	99.7	%	97.4	%	100.0	%	89.8	%
June 30, 2011
Number of Buildings	108		17		66		5		18		21		8		2		2		2		249
Rentable Square Feet	8,518,317		2,828,117		3,784,852		711,459		820,692		1,569,336		915,429		437,718		362,209		295,842		20,243,971
Occupied %	90.0	%	87.6	%	83.9	%	71.0	%	87.0	%	76.0	%	100.0	%	85.8	%	95.4	%	100.0	%	87.3	%
Leased %	91.8	%	89.3	%	85.1	%	84.0	%	87.4	%	76.7	%	100.0	%	99.7	%	98.3	%	100.0	%	89.4	%
March 31, 2011
Number of Buildings	111		17		66		5		18		21		8		2		2		2		252
Rentable Square Feet	8,557,526		2,809,317		3,764,456		711,459		820,692		1,571,334		915,429		375,760		361,674		295,842		20,183,489
Occupied %	89.1	%	86.4	%	83.6	%	70.1	%	88.8	%	76.1	%	100.0	%	100.0	%	95.4	%	100.0	%	87.0	%
Leased %	91.4	%	88.8	%	85.7	%	83.2	%	88.8	%	76.3	%	100.0	%	100.0	%	95.4	%	100.0	%	89.2	%
December 31, 2010
Number of Buildings	111		17		66		5		18		21		8		2		2		2		252
Rentable Square Feet	8,432,626		2,772,817		3,750,398		695,306		821,812		1,568,926		915,127		375,760		361,674		295,842		19,990,288
Occupied %	89.5	%	91.9	%	85.0	%	71.4	%	86.8	%	76.2	%	100.0	%	100.0	%	98.5	%	100.0	%	88.2	%
Leased %	90.6	%	93.1	%	85.8	%	87.1	%	86.8	%	76.2	%	100.0	%	100.0	%	98.5	%	100.0	%	89.5	%
September 30, 2010
Number of Buildings	110		16		65		5		18		21		8		2		2		2		249
Rentable Square Feet	8,402,671		2,763,656		3,728,034		695,184		821,812		1,568,926		915,127		375,760		361,674		295,842		19,928,686
Occupied %	89.1	%	91.9	%	80.4	%	72.5	%	89.2	%	76.7	%	100.0	%	100.0	%	99.6	%	100.0	%	87.4	%
Leased %	90.3	%	93.2	%	83.5	%	73.3	%	89.7	%	76.7	%	100.0	%	100.0	%	99.6	%	100.0	%	88.7	%
Summary of Operating, Construction and Redevelopment Office Properties Ownership at September 30, 2011
							Consolidated		Unconsolidated		Total
			Wholly-Owned		Consolidated JV		Portfolio		JV		Portfolio
Operating Properties
# of Properties			246		4		250		16		266
Total Square Feet			20,204,583		442,562		20,647,145		671,260		21,318,405
Leased Square Feet			18,134,802		281,403		18,416,205		480,926		18,897,131
% Leased			89.8	%	63.6	%	89.2	%	71.6	%	88.6	%
Under Construction
# of Properties			9		1		10		—		10
Total Square Feet			1,056,815		114,891		1,171,706		—		1,171,706
Under Redevelopment
# of Properties			2		—		2		—		2
Total Square Feet			297,240		—		297,240		—		297,240
Partially Operational Prop. (1)
# of Constr.prop.			(2	)	—		(2	)	—		(2	)
# of Redevelop. Prop.			(1	)	—		(1	)	—		(1	)
Construction total sf			(88,850	)	—		(88,850	)	—		(88,850	)
Redevelop. total sf			(42,910	)	—		(42,910	)	—		(42,910	)
Total
# of Properties			254		5		259		16		275
Total Square Feet			21,426,878		557,453		21,984,331		671,260		22,655,591

(1) Adjustment for partially operational properties included in both operating properties and under construction or redevelopment.

9

Third Quarter 2011

Office Properties by Region - September 30, 2011

Wholly Owned Properties

Operating Property Count		Submarket	Business Park	Year Built or Renovated	S or M	Total Operational Square Feet	Total Square Feet Under Construction / Redevelopment
	Baltimore /Washington Corridor
1	2730 Hercules Road	BWI Airport	NBP	1990	M	238,007
2	300 Sentinel Drive (300 NBP)	BWI Airport	NBP	2009	M	193,296
3	304 Sentinel Drive (304 NBP)	BWI Airport	NBP	2005	M	162,483
4	2720 Technology Drive (220 NBP)	BWI Airport	NBP	2004	M	158,929
5	306 Sentinel Drive (306 NBP)	BWI Airport	NBP	2006	M	155,367
6	302 Sentinel Drive (302 NBP)	BWI Airport	NBP	2007	M	153,535
7	2711 Technology Drive (211 NBP)	BWI Airport	NBP	2002	M	152,209
8	308 Sentinel Drive (308 NBP)	BWI Airport	NBP	2010	M	151,207
9	318 Sentinel Way (318 NBP)	BWI Airport	NBP	2005	M	125,635
10	322 Sentinel Way (322 NBP)	BWI Airport	NBP	2006	M	125,487
11	320 Sentinel Way (320 NBP)	BWI Airport	NBP	2007	M	125,325
	316 National Business Parkway	BWI Airport	NBP		M		125,150
12	324 Sentinel Way (324 NBP)	BWI Airport	NBP	2010	M	125,118
13	140 National Business Parkway	BWI Airport	NBP	2003	M	119,466
14	132 National Business Parkway	BWI Airport	NBP	2000	M	118,150
15	2721 Technology Drive (221 NBP)	BWI Airport	NBP	2000	M	117,242
16	2701 Technology Drive (201 NBP)	BWI Airport	NBP	2001	M	117,068
17	430 National Business Parkway	BWI Airport	NBP	2011	M	61,299	48,529
	410 National Business Parkway	BWI Airport	NBP		M		110,362
18	2691 Technology Drive (191 NBP)	BWI Airport	NBP	2005	M	103,578
19	134 National Business Parkway	BWI Airport	NBP	1999	M	92,327
20	133 National Business Parkway	BWI Airport	NBP	1997	M	88,057
21	141 National Business Parkway	BWI Airport	NBP	1990	M	87,364
22	135 National Business Parkway	BWI Airport	NBP	1998	M	86,437
23	131 National Business Parkway	BWI Airport	NBP	1990	M	69,702
24	114 National Business Parkway	BWI Airport	NBP	2002	S	10,113
25	314 Sentinel Way (314 NBP)	BWI Airport	NBP	2008	S	4,462
						2,941,863	284,041
1	1550 West Nursery Road	BWI Airport	APS	2009	M	161,689
2	1306 Concourse Drive	BWI Airport	APS	1990	M	116,259
3	920 Elkridge Landing Road	BWI Airport	APS	1982	M	103,415
4	1304 Concourse Drive	BWI Airport	APS	2002	M	101,124
5	900 Elkridge Landing Road	BWI Airport	APS	1982	M	101,005
6	1199 Winterson Road	BWI Airport	APS	1988	M	100,104
7	880 Elkridge Landing Road	BWI Airport	APS	1981	M	99,646
8	1302 Concourse Drive	BWI Airport	APS	1996	M	83,717
9	881 Elkridge Landing Road	BWI Airport	APS	1986	M	75,385
10	1099 Winterson Road	BWI Airport	APS	1988	M	71,675
11	849 International Drive	BWI Airport	APS	1988	M	69,018
12	1190 Winterson Road	BWI Airport	APS	1987	M	69,016
13	911 Elkridge Landing Road	BWI Airport	APS	1985	M	68,373
14	1201 Winterson Road	BWI Airport	APS	1985	M	67,903
15	999 Corporate Boulevard	BWI Airport	APS	2000	M	67,083
16	891 Elkridge Landing Road	BWI Airport	APS	1984	M	57,987
17	901 Elkridge Landing Road	BWI Airport	APS	1984	M	57,872
18	800 International Drive	BWI Airport	APS	1988	S	57,379
19	930 International Drive	BWI Airport	APS	1986	S	56,685
20	900 International Drive	BWI Airport	APS	1986	S	57,140
21	921 Elkridge Landing Road	BWI Airport	APS	1983	M	56,452
22	938 Elkridge Landing Road	BWI Airport	APS	1984	M	56,270
23	939 Elkridge Landing Road	BWI Airport	APS	1983	M	54,224
24	870 Elkridge Landing Road	BWI Airport	APS	1981	S	5,810
						1,815,231
1	7240 Parkway Drive	BWI Airport	Comm./Pkwy.	1985	M	74,475
2	7467 Ridge Road	BWI Airport	Comm./Pkwy.	1990	M	74,545
3	7272 Park Circle Drive	BWI Airport	Comm./Pkwy.	1991/1996	M	60,041
4	7318 Parkway Drive	BWI Airport	Comm./Pkwy.	1984	S	59,204
5	7320 Parkway Drive	BWI Airport	Comm./Pkwy.	1983	S	56,964
6	1340 Ashton Road	BWI Airport	Comm./Pkwy.	1989	S	45,867
7	1362 Mellon Road	BWI Airport	Comm./Pkwy.	2006	M	43,232
8	1334 Ashton Road	BWI Airport	Comm./Pkwy.	1989	S	38,128
9	1331 Ashton Road	BWI Airport	Comm./Pkwy.	1989	S	28,906
10	1341 Ashton Road	BWI Airport	Comm./Pkwy.	1989	S	15,314
11	1343 Ashton Road	BWI Airport	Comm./Pkwy.	1989	S	9,903
						506,579	—
60	Subtotal (continued on next page)					5,263,673	284,041

The S or M notation indicates single story or multi-story, respectively.

10

Third Quarter 2011

Office Properties by Region - September 30, 2011

Wholly Owned Properties

Operating Property Count		Submarket	Business Park	Year Built or Renovated	S or M	Total Operational Square Feet	Total Square Feet Under Construction / Redevelopment
60	Subtotal (continued from prior page)					5,263,673	284,041
1	5520 Research Park Drive (UMBC) (1)	BWI Airport	bwtech@UMBC	2009	M	103,333
2	5522 Research Park Drive (UMBC) (1)	BWI Airport	bwtech@UMBC	2007	S	23,925
						127,258
1	2500 Riva Road	Annapolis		2000	M	155,000
1	Old Annapolis Road	Howard Co. Perimeter	Oakland Ridge	1985	M	171,436
1	7125 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	1973/1999	M	471,073
2	7000 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	1999	M	145,386
3	6721 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	2009	M	131,451
4	6711 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	2006-2007	M	124,048
5	6731 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	2002	M	123,576
6	6950 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	1998	M	112,861
7	6940 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	1999	M	108,652
8	7067 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	2001	M	85,393
9	8621 Robert Fulton Drive	Howard Co. Perimeter	Columbia Gateway	2005-2006	M	83,734
10	6700 Alexander Bell Drive	Howard Co. Perimeter	Columbia Gateway	1988	M	76,359
11	6750 Alexander Bell Drive	Howard Co. Perimeter	Columbia Gateway	2001	M	75,328
12	6740 Alexander Bell Drive	Howard Co. Perimeter	Columbia Gateway	1992	M	63,161
13	7015 Albert Einstein Drive	Howard Co. Perimeter	Columbia Gateway	1999	S	62,216
14	8671 Robert Fulton Drive	Howard Co. Perimeter	Columbia Gateway	2002	S	55,688
15	6716 Alexander Bell Drive	Howard Co. Perimeter	Columbia Gateway	1990	M	52,114
16	8661 Robert Fulton Drive	Howard Co. Perimeter	Columbia Gateway	2002	S	48,666
17	7142 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	1994	S	47,668
18	7130 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	1989	S	45,882
19	6708 Alexander Bell Drive	Howard Co. Perimeter	Columbia Gateway	1988	M	39,128
20	7065 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	2000	S	38,560
21	7138 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	1990	S	38,285
22	7063 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	2000	S	36,295
23	6760 Alexander Bell Drive	Howard Co. Perimeter	Columbia Gateway	1991	M	36,227
24	7150 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	1991	S	34,734
25	7061 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	2000	M	30,730
26	6724 Alexander Bell Drive	Howard Co. Perimeter	Columbia Gateway	2001	M	28,107
27	7134 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	1990	S	21,931
28	6741 Columbia Gateway Drive	Howard Co. Perimeter	Columbia Gateway	2008	S	4,592
						2,221,845	—
1	7200 Riverwood Drive	Howard Co. Perimeter	Rivers Corporate Park	1986	S	160,000
	7205 Riverwood Drive	Howard Co. Perimeter	Rivers Corporate Park				89,295
2	7160 Riverwood Drive	Howard Co. Perimeter	Rivers Corporate Park	2000	M	62,041
3	9140 Guilford Road	Howard Co. Perimeter	Rivers Corporate Park	1983	S	40,288
4	7150 Riverwood Drive	Howard Co. Perimeter	Rivers Corporate Park	2000	M	39,496
5	9160 Guilford Road	Howard Co. Perimeter	Rivers Corporate Park	1984	M	36,919
6	7170 Riverwood Drive	Howard Co. Perimeter	Rivers Corporate Park	2000	M	27,891
7	9150 Guilford Road	Howard Co. Perimeter	Rivers Corporate Park	1984	S	18,405
8	10280 Old Columbia Road	Howard Co. Perimeter	Rivers Corporate Park	1988/2001	S	16,145
9	10270 Old Columbia Road	Howard Co. Perimeter	Rivers Corporate Park	1988/2001	S	15,914
10	9130 Guilford Road	Howard Co. Perimeter	Rivers Corporate Park	1984	S	13,647
11	10290 Old Columbia Road	Howard Co. Perimeter	Rivers Corporate Park	1988/2001	S	10,229
						440,975	89,295
1	9720 Patuxent Woods Drive	Howard Co. Perimeter	Owen Brown South	1986/2001	M	39,480
2	9740 Patuxent Woods Drive	Howard Co. Perimeter	Owen Brown South	1986/2001	M	37,520
3	9700 Patuxent Woods Drive	Howard Co. Perimeter	Owen Brown South	1986/2001	M	31,117
4	9730 Patuxent Woods Drive	Howard Co. Perimeter	Owen Brown South	1986/2001	M	30,495
5	9710 Patuxent Woods Drive	Howard Co. Perimeter	Owen Brown South	1986/2001	M	14,778
						153,390	—
1	9020 Mendenhall Court	Howard Co. Perimeter	Sieling Business Park	1982/2005	S	47,603
109	Total Baltimore/Washington Corridor					8,581,180	373,336

The S or M notation indicates single story or multi-story building, respectively.

(1) This property is a land-lease property.

11

Third Quarter 2011

Office Properties by Region - September 30, 2011

Wholly Owned Properties

Operating Property Count		Submarket	Business Park	Year Built or Renovated	S or M	Total Operational Square Feet	Total Square Feet Under Construction / Redevelopment
	St. Mary’s & King George Counties
1	22309 Exploration Drive	St. Mary’s County	Exploration Park	1984/1997	M	98,860
2	22289 Exploration Drive	St. Mary’s County	Exploration Park	2000	M	58,633
3	22299 Exploration Drive	St. Mary’s County	Exploration Park	1998	M	58,132
4	22300 Exploration Drive	St. Mary’s County	Exploration Park	1997	M	45,093
						260,718	—
1	46591 Expedition Drive	St. Mary’s County	Expedition Park	2005-2006	M	59,843
2	46579 Expedition Drive	St. Mary’s County	Expedition Park	2002	M	58,989
						118,832	—
	45310 Abell House Lane	St. Mary’s County	Wildewood Tech Park		M		82,842
1	44425 Pecan Court	St. Mary’s County	Wildewood Tech Park	1997	M	58,694
2	44408 Pecan Court	St. Mary’s County	Wildewood Tech Park	1986	S	49,808
3	23535 Cottonwood Parkway	St. Mary’s County	Wildewood Tech Park	1984	M	46,656
4	44417 Pecan Court	St. Mary’s County	Wildewood Tech Park	1989	S	29,053
5	44414 Pecan Court	St. Mary’s County	Wildewood Tech Park	1986	S	25,444
6	44420 Pecan Court	St. Mary’s County	Wildewood Tech Park	1989	S	25,338
						234,993	82,842
1	16480 Commerce Drive	King George County	Dahlgren Technology Center	2000	M	70,875
2	16541 Commerce Drive	King George County	Dahlgren Technology Center	1996	S	37,292
3	16539 Commerce Drive	King George County	Dahlgren Technology Center	1990	S	32,257
4	16442 Commerce Drive	King George County	Dahlgren Technology Center	2002	S	25,606
5	16501 Commerce Drive	King George County	Dahlgren Technology Center	2002	S	22,833
6	16543 Commerce Drive	King George County	Dahlgren Technology Center	2002	S	17,286
						206,149	—
18	Total St. Mary’s & King George Counties					820,692	82,842
	Northern Virginia
1	15000 Conference Center Drive	Dulles South	Westfields Corporate Center	1989	M	444,869
2	15010 Conference Center Drive	Dulles South	Westfields Corporate Center	2006	M	223,610
3	15049 Conference Center Drive	Dulles South	Westfields Corporate Center	1997	M	152,993
4	15059 Conference Center Drive	Dulles South	Westfields Corporate Center	2000	M	145,224
5	14900 Conference Center Drive	Dulles South	Westfields Corporate Center	1999	M	126,158
6	14280 Park Meadow Drive	Dulles South	Westfields Corporate Center	1999	M	114,409
7	4851 Stonecroft Boulevard	Dulles South	Westfields Corporate Center	2004	M	88,099
8	14850 Conference Center Drive	Dulles South	Westfields Corporate Center	2000	M	72,194
9	14840 Conference Center Drive	Dulles South	Westfields Corporate Center	2000	M	69,938
						1,437,494	—
1	13200 Woodland Park Road	Herndon	Woodland Park	2002	M	396,837
1	13454 Sunrise Valley Road	Herndon	Dulles Tech	1998	M	112,111
2	13450 Sunrise Valley Road	Herndon	Dulles Tech	1998	M	53,379
						165,490	—
1	3120 Fairview Park Drive	Merrifield	Fairview Park	2008	M	42,910	140,530
	7770 Backlick Road	Springfield	Patriot Ridge				236,685
1	1751 Pinnacle Drive	Tysons Corner		1989/1995	M	260,150
2	1753 Pinnacle Drive	Tysons Corner		1976/2004	M	186,707
3	1550 Westbranch Drive	Tysons Corner		2002	M	160,461
						607,318	—
1	2900 Towerview Road	Herndon	Renaissance Park	1982/2008	M	151,497
17	Total Northern Virginia					2,801,546	377,215
	Other
1	11751 Meadowville Lane	Richmond Southwest	Meadowville Technology Park	2007	M	193,000
1	201 Technology Park Drive	Southwest Virginia	Russell Regional Business Tech Park	2007	S	102,842
1	310 The Bridge Street	Huntsville	Bridge Street Town Center	2009	M	138,466
3	Total Other					434,308	—

The S or M notation indicates single story or multi-story building, respectively.

12

Third Quarter 2011

Office Properties by Region - September 30, 2011

Wholly Owned Properties

Operating Property Count		Submarket	Business Park	Year Built or Renovated	S or M	Total Operational Square Feet	Total Square Feet Under Construction / Redevelopment
	Greater Philadelphia
1	785 Jolly Road	Blue Bell	Arborcrest	1996	M	219,065	—
2	801 Lakeview Drive	Blue Bell	Arborcrest	1994	M	218,653
	751 Arbor Way	Blue Bell	Arborcrest				113,800
2	Total Greater Philadelphia					437,718	113,800
	San Antonio, Texas
2	7700 Potranco Road	San Antonio Northwest	Sentry Gateway	1982/1985	M	508,412
3	8000 Potranco Road	San Antonio Northwest	Sentry Gateway	2010	M	125,157
4	8030 Potranco Road	San Antonio Northwest	Sentry Gateway	2010	M	125,155
	100 Sentry Gateway	San Antonio Northwest	Sentry Gateway				94,961
5	7700-5 Potranco-Warehouse	San Antonio Northwest	Sentry Gateway	2009	S	25,056
6	7700-1 Potranco Road	San Antonio Northwest	Sentry Gateway	2007	S	8,674
						792,454	94,961
1	1560 Cable Ranch Road - Building B	San Antonio Northwest	151 Technology Center	1985/2006	M	77,040
2	1560 Cable Ranch Road - Building A	San Antonio Northwest	151 Technology Center	1985/2007	M	45,935
						122,975	—
8	Total San Antonio, Texas					915,429	94,961
	Colorado Springs, Colorado
1	985 Space Center Drive	Colorado Springs East	Patriot Park	1989	M	104,028
2	655 Space Center Drive	Colorado Springs East	Patriot Park	2008	M	103,970
3	565 Space Center Drive	Colorado Springs East	Patriot Park	2009	M	89,899
4	745 Space Center Drive	Colorado Springs East	Patriot Park	2006	M	51,500
5	980 Technology Court	Colorado Springs East	Patriot Park	1995	S	33,207
6	525 Babcock Road	Colorado Springs East	Patriot Park	1967	S	14,000
						396,604	—
1	1055 North Newport Road	Colorado Springs East	Aerotech Commerce Park	2007 - 2008	M	59,763
1	3535 Northrop Grumman Point	Colorado Springs East	Colorado Springs Airport	2008	M	124,305
1	1670 North Newport Road	Colorado Springs East	Newport	1986 - 1987	M	67,500
2	1915 Aerotech Drive	Colorado Springs East		1985	S	37,946
3	1925 Aerotech Drive	Colorado Springs East		1985	S	37,946
						143,392	—
1	10807 New Allegiance Drive	I-25 North Corridor	InterQuest Office	2009	M	145,723
2	9965 Federal Drive	I-25 North Corridor	InterQuest Office	1983/2007	M	74,749
3	9945 Federal Drive	I-25 North Corridor	InterQuest Office	2009	S	74,005
4	9950 Federal Drive	I-25 North Corridor	InterQuest Office	2001	S	66,223
5	12515 Academy Ridge View	I-25 North Corridor	InterQuest Office	2006	M	61,372
6	9925 Federal Drive	I-25 North Corridor	InterQuest Office	2008	S	53,788
7	9960 Federal Drive	I-25 North Corridor	InterQuest Office	2001	S	46,948
						522,808	—
1	5725 Mark Dabling Boulevard	Colorado Springs Northwest	Northcreek	1984	M	108,976
2	5775 Mark Dabling Boulevard	Colorado Springs Northwest	Northcreek	1984	M	108,640
3	5755 Mark Dabling Boulevard	Colorado Springs Northwest	Northcreek	1989	M	104,848
						322,464	—
21	Total Colorado Springs, Colorado					1,569,336	—
	Washington, DC - Capitol Riverfront
1	1201 M Street	Washington, DC - Capitol Riverfront	Maritime Plaza	2001	M	203,296
2	1220 12th Street	Washington, DC - Capitol Riverfront	Maritime Plaza	2003	M	158,913
	Total Washington, DC - Capitol Riverfront					362,209	—

The S or M notation indicates single story or multi-story building, respectively.

13

Third Quarter 2011

Office Properties by Region - September 30, 2011

Wholly Owned Properties

Operating Property Count		Submarket	Business Park	Year Built or Renovated	S or M	Total Operational Square Feet	Total Square Feet Under Construction / Redevelopment
	Suburban Maryland
1	11800 Tech Road	North Silver Spring	Montgomery Industrial	1989	M	228,179
1	400 Professional Drive	Gaithersburg	Crown Point	2000	M	129,853
1	110 Thomas Johnson Drive	Frederick		1987/1999	M	120,318
1	45 West Gude Drive	Rockville		1987	M	122,555
2	15 West Gude Drive	Rockville		1986	M	108,485
						231,040	—
5	Total Suburban Maryland					709,390	—
	Greater Baltimore
1	11311 McCormick Road	Hunt Valley/Rte 83 Corridor	Hunt Valley Business Comm.	1984/1994	M	214,704
2	200 International Circle	Hunt Valley/Rte 83 Corridor	Hunt Valley Business Comm.	1987	M	125,352
3	226 Schilling Circle	Hunt Valley/Rte 83 Corridor	Hunt Valley Business Comm.	1980	M	97,309
4	201 International Circle	Hunt Valley/Rte 83 Corridor	Hunt Valley Business Comm.	1982	M	78,243
5	11011 McCormick Road	Hunt Valley/Rte 83 Corridor	Hunt Valley Business Comm.	1974	M	57,104
6	222 Schilling Circle	Hunt Valley/Rte 83 Corridor	Hunt Valley Business Comm.	1978/1997	M	28,618
7	224 Schilling Circle	Hunt Valley/Rte 83 Corridor	Hunt Valley Business Comm.	1978/1997	M	27,575
						628,905	—
1	10150 York Road	Hunt Valley/Rte 83 Corridor		1985	M	175,207
2	9690 Deereco Road	Hunt Valley/Rte 83 Corridor		1988	M	134,950
3	375 West Padonia Road	Hunt Valley/Rte 83 Corridor		1986	M	104,885
						415,042	—
1	7210 Ambassador Road	Baltimore County Westside	Rutherford Business Center	1972	S	79,739
2	7152 Windsor Boulevard	Baltimore County Westside	Rutherford Business Center	1986	S	58,074
3	21 Governor’s Court	Baltimore County Westside	Rutherford Business Center	1981/1995	M	56,384
4	7125 Ambassador Road	Baltimore County Westside	Rutherford Business Center	1985	M	54,627
5	7104 Ambassador Road	Baltimore County Westside	Rutherford Business Center	1988	M	30,239
6	15 Governor’s Court	Baltimore County Westside	Rutherford Business Center	1981	S	14,890
7	17 Governor’s Court	Baltimore County Westside	Rutherford Business Center	1981	S	14,454
8	7127 Ambassador Road	Baltimore County Westside	Rutherford Business Center	1985	S	11,630
9	7129 Ambassador Road	Baltimore County Westside	Rutherford Business Center	1985	S	11,133
10	7106 Ambassador Road	Baltimore County Westside	Rutherford Business Center	1988	S	8,899
11	7108 Ambassador Road	Baltimore County Westside	Rutherford Business Center	1988	S	8,810
12	7102 Ambassador Road	Baltimore County Westside	Rutherford Business Center	1988	S	8,794
13	7131 Ambassador Road	Baltimore County Westside	Rutherford Business Center	1985	S	7,734
						365,407	—
1	1501 South Clinton Street	Baltimore	Canton Crossing	2006	M	481,277
	206 Research Boulevard	Harford County	North Gate Business Park				128,119
1	209 Research Boulevard	Harford County	North Gate Business Park	2010	M	77,192
2	210 Research Boulevard	Harford County	North Gate Business Park	2010	M	27,551	52,022
						104,743	180,141
26	Subtotal (continued on next page)					1,995,374	180,141

The S or M notation indicates single story or multi-story building, respectively.

14

Third Quarter 2011

Office Properties by Region - September 30, 2011

Wholly Owned Properties

Operating Property Count		Submarket	Business Park	Year Built or Renovated	S or M	Total Operational Square Feet	Total Square Feet Under Construction / Redevelopment
26	Subtotal (continued from prior page)					1,995,374	180,141
1	4940 Campbell Boulevard	White Marsh	Campbell Corporate Center	1990	M	50,415
1	8110 Corporate Drive	White Marsh	Corporate Place	2001	M	79,091
2	8140 Corporate Drive	White Marsh	Corporate Place	2003	M	76,271
						155,362	—
1	9910 Franklin Square Drive	White Marsh	Franklin Ridge	2005	S	57,812
2	9920 Franklin Square Drive	White Marsh	Franklin Ridge	2006	S	42,891
3	9930 Franklin Square Drive	White Marsh	Franklin Ridge	2001	S	39,750
4	9900 Franklin Square Drive	White Marsh	Franklin Ridge	1999	S	33,800
5	9940 Franklin Square Drive	White Marsh	Franklin Ridge	2000	S	32,242
						206,495	—
1	8020 Corporate Drive	White Marsh	McLean Ridge	1997	S	50,796
2	8094 Sandpiper Circle	White Marsh	McLean Ridge	1998	S	49,585
3	8098 Sandpiper Circle	White Marsh	McLean Ridge	1998	S	46,485
4	8010 Corporate Drive	White Marsh	McLean Ridge	1998	S	38,487
						185,353	—
1	5355 Nottingham Ridge Road	White Marsh	Nottingham Ridge	2005	S	35,930
2	5325 Nottingham Ridge Road	White Marsh	Nottingham Ridge	2002	S	35,678
						71,608	—
1	7941-7949 Corporate Drive	White Marsh	Tyler Ridge	1996	S	57,782
2	8007 Corporate Drive	White Marsh	Tyler Ridge	1995	S	41,799
3	8019 Corporate Drive	White Marsh	Tyler Ridge	1990	S	32,424
4	8013 Corporate Drive	White Marsh	Tyler Ridge	1990	S	29,995
5	8003 Corporate Drive	White Marsh	Tyler Ridge	1999	S	17,599
6	8015 Corporate Drive	White Marsh	Tyler Ridge	1990	S	15,669
7	8023 Corporate Drive	White Marsh	Tyler Ridge	1990	S	9,486
						204,754	—
1	5020 Campbell Boulevard	White Marsh	White Marsh Business Center	1986-1988	S	43,623
2	5024 Campbell Boulevard	White Marsh	White Marsh Business Center	1986-1988	S	33,710
3	5026 Campbell Boulevard	White Marsh	White Marsh Business Center	1986-1988	S	30,163
4	5022 Campbell Boulevard	White Marsh	White Marsh Business Center	1986-1988	S	26,748
						134,244	—
1	10001 Franklin Square Drive	White Marsh	White Marsh Commerce Center	1997	S	218,215
1	8114 Sandpiper Circle	White Marsh	White Marsh Health Center	1986	S	45,803
1	4979 Mercantile Road	White Marsh	White Marsh Hi-Tech Center	1985	S	49,590
2	4969 Mercantile Road	White Marsh	White Marsh Hi-Tech Center	1983	S	47,132
						96,722	—
1	7939 Honeygo Boulevard	White Marsh	White Marsh Professional Center	1984	M	28,208
2	8133 Perry Hall Boulevard	White Marsh	White Marsh Professional Center	1988	M	27,995
3	7923 Honeygo Boulevard	White Marsh	White Marsh Professional Center	1985	M	23,481
						79,684	—
1	8031 Corporate Drive	White Marsh		1988/2004	S	66,000
2	8615 Ridgely’s Choice Drive	White Marsh		2005	M	37,746
3	8029 Corporate Drive	White Marsh		1988/2004	S	25,000
						128,746	—
61	Total Greater Baltimore					3,572,775	180,141
246	TOTAL WHOLLY-OWNED OFFICE PROPERTY PORTFOLIO					20,204,583	1,222,295

The S or M notation indicates single story or multi-story building, respectively.

15

Third Quarter 2011

Renewal Analysis for Wholly Owned Office Properties

for Periods Ended September 30, 2011

	Baltimore/ Washington Corridor			Northern Virginia			Greater Baltimore			Suburban Maryland			St. Mary’s and King George Counties			Colorado Springs			Greater Philadelphia			Washington DC-Capital Riverfront			Total Office
Quarter Ended September 30, 2011:
Expiring Square Feet	269,959			10,129			319,184			13,511			68,178			17,325			—			7,091			705,377
Vacated Square Feet	20,023			—			78,404			—			13,851			17,325			—			—			129,603
Renewed Square Feet	249,936			10,129			240,780			13,511			54,327			—			—			7,091			575,774
Retention Rate (% based upon square feet)	92.58		%	100.00		%	75.44		%	100.00		%	79.68		%	0.00		%	0.00		%	100.00		%	81.63		%
Renewed Space Only:
Average Committed Cost per Square Foot	$	4.11		$	1.32		$	7.54		$	1.85		$	1.47		$	0.00		$	0.00		$	20.21		$	5.39
Weighted Average Lease Term in years	2.9			1.1			7.2			3.7			2.4			—			—			7.0			4.7
Change in Total Rent - GAAP	8.5		%	-2.0		%	12.5		%	-0.7		%	15.0		%	0.0		%	0.0		%	8.4		%	9.8		%
Change in Total Rent - Cash	1.4		%	0.0		%	-9.3		%	-4.7		%	10.6		%	0.0		%	0.0		%	-0.6		%	-2.3		%
Renewed & Retenanted Space:
Leased Square Feet	276,914			12,260			284,607			13,511			56,002			1,024			—			9,726			654,044
Average Committed Cost per Square Foot	$	4.60		$	10.06		$	11.71		$	1.85		$	1.43		$	0.00		$	0.00		$	24.64		$	7.76
Weighted Average Lease Term in years	3.0			2.7			7.5			3.7			2.4			1.0			—			7.3			4.9
Change in Total Rent - GAAP	7.2		%	-1.0		%	12.7		%	-0.7		%	14.5		%	-1.4		%	0.0		%	7.5		%	9.3		%
Change in Total Rent - Cash	0.5		%	-0.9		%	-7.0		%	-4.7		%	10.2		%	0.0		%	0.0		%	-2.0		%	-2.1		%
Construction and Redevelopment Space:
Leased Square Feet	84,586			—			—			—			—			—			26,309			—			110,895
Average Committed Cost Per Square Foot	$	65.73		$	0.00		$	0.00		$	0.00		$	0.00		$	0.00		$	67.89		$	0.00		$	66.24
Weighted Average Lease Term in years	5.1			—			—			—			—			—			9.5			—			6.2
Other First Generation Space
Leased Square Feet	52,844			—			46,016			7,259			—			8,086			—			—			114,205
Average Committed Cost Per Square Foot	$	10.64		$	0.00		$	57.33		$	19.80		$	0.00		$	24.30		$	0.00		$	0.00		$	31.00
Weighted Average Lease Term in years	5.0			—			10.4			5.1			—			6.1			—			—			7.3
Total Square Feet Leased	414,344			12,260			330,623			20,770			56,002			9,110			26,309			9,726			879,144
Nine Months Ended September 30, 2011:
Expiring Square Feet	709,828			582,097			878,655			106,809			120,843			103,857			219,065			28,504			2,749,658
Vacated Square Feet	130,615			181,782			231,620			—			36,855			22,503			—			18,201			621,576
Renewed Square Feet	579,213			400,315			647,035			106,809			83,988			81,354			219,065			10,303			2,128,082
Retention Rate (% based upon square feet)	81.6		%	68.8		%	73.6		%	100.0		%	69.5		%	78.3		%	100.0		%	36.2		%	77.4		%
Renewed Space Only:
Average Committed Cost per Square Foot	$	10.86		$	6.21		$	13.45		$	8.56		$	2.09		$	13.24		$	2.37		$	14.19		$	9.55
Weighted Average Lease Term in years	4.7			2.6			5.8			3.9			2.1			4.6			3.0			5.1			4.3
Change in Total Rent - GAAP	5.7		%	3.9		%	6.3		%	-8.3		%	8.7		%	14.2		%	7.8		%	7.5		%	5.2		%
Change in Total Rent - Cash	-0.6		%	-0.7		%	-9.1		%	-11.2		%	4.1		%	-2.2		%	2.8		%	1.1		%	-3.7		%
Renewed & Retenanted Space:
Leased Square Feet	772,685			513,592			722,070			112,644			109,490			92,570			219,065			24,313			2,566,429
Average Committed Cost per Square Foot	$	14.00		$	15.13		$	14.54		$	8.77		$	4.70		$	11.76		$	2.37		$	14.19		$	12.76
Weighted Average Lease Term in years	5.0			3.8			5.9			4.0			2.1			4.3			3.0			5.1			4.6
Change in Total Rent - GAAP	5.1		%	3.5		%	5.9		%	-11.2		%	14.0		%	8.7		%	7.8		%	4.9		%	4.7		%
Change in Total Rent - Cash	-0.9		%	-1.2		%	-8.6		%	-13.8		%	9.4		%	-5.7		%	2.8		%	-0.6		%	-3.5		%
Construction and Redevelopment Space:
Leased Square Feet	187,094			62,442			—			—			—			—			86,918			—			336,454
Average Committed Cost Per Square Foot	$	54.85		$	78.29		$	0.00		$	0.00		$	0.00		$	0.00		$	58.73		$	0.00		$	60.20
Weighted Average Lease Term in years	5.9			7.7			—			—			—			—			9.9			—			7.3
Other First Generation Space
Leased Square Feet	81,765			—			88,047			7,259			—			20,636			—			—			197,707
Average Committed Cost Per Square Foot	$	15.86		$	0.00		$	47.56		$	19.80		$	0.00		$	22.81		$	0.00		$	0.00		$	30.84
Weighted Average Lease Term in years	5.3			—			8.5			5.1			—			5.2			—			—			6.7
Total Square Feet Leased	1,041,544			576,034			810,117			119,903			109,490			113,206			305,983			24,313			3,100,590

Notes:  No renewal or retenanting activity transpired in our San Antonio or Other regions.

Activity is exclusive of owner occupied space and leases with less than a one-year term.

Retention rate includes early renewals.

16

Third Quarter 2011

Lease Expiration Analysis

(wholly owned office properties)

							Total				Total
							Annual. Rental		Percentage		Annual. Rental
		Square			Percentage		Revenue of		of Total		Revenue of
Year and Region	Number	Footage	Percentage of		of Total		Expiring		Annualized Rental		Expiring Leases
of Lease	of Leases	of Leases	Period’s Expiring		Occupied		Leases (3)		Revenue		per Occupied
Expiration (2)	Expiring	Expiring	Square Feet		Square Feet		(000’s)		Expiring		Square Foot
Baltimore/Washington Corridor	28	279,461	44.9	%	1.6	%	$	6,855	1.5	%	$	24.53
Northern Virginia	2	19,422	3.1	%	0.1	%	533		0.1	%	27.47
Greater Baltimore	15	151,127	24.3	%	0.9	%	2,429		0.5	%	16.07
Suburban Maryland	1	18,748	3.0	%	0.1	%	537		0.1	%	28.66
St. Mary’s and King George Cos.	3	40,895	6.6	%	0.2	%	974		0.2	%	23.81
Colorado Springs	1	46,830	7.5	%	0.3	%	535		0.1	%	11.43
Washington, DC-Capitol Riverfront	4	66,275	10.6	%	0.4	%	3,196		0.7	%	48.22
2011	54	622,758	100.0	%	3.5	%	15,060		3.2	%	24.18
Baltimore/Washington Corridor	49	1,086,674	47.5	%	6.1	%	28,630		6.1	%	26.35
Northern Virginia	18	327,068	14.3	%	1.8	%	9,437		2.0	%	28.85
Greater Baltimore	50	366,642	16.0	%	2.1	%	7,700		1.7	%	21.00
Suburban Maryland	2	18,459	0.8	%	0.1	%	328		0.1	%	17.75
St. Mary’s and King George Cos.	17	331,787	14.5	%	1.9	%	6,459		1.4	%	19.47
Colorado Springs	9	71,742	3.1	%	0.4	%	1,417		0.3	%	19.76
San Antonio	2	78,359	3.4	%	0.4	%	1,392		0.3	%	17.76
Washington, DC-Capitol Riverfront	2	4,709	0.2	%	0.0	%	220		0.0	%	46.72
2012	149	2,285,440	100.0	%	12.9	%	55,583		11.9	%	24.32
Baltimore/Washington Corridor	50	1,194,831	63.6	%	6.7	%	38,435		8.3	%	32.17
Northern Virginia	11	146,393	7.8	%	0.8	%	3,830		0.8	%	26.16
Greater Baltimore	33	143,106	7.6	%	0.8	%	3,149		0.7	%	22.00
Suburban Maryland	2	8,914	0.5	%	0.1	%	243		0.1	%	27.25
St. Mary’s and King George Cos.	7	114,699	6.1	%	0.6	%	2,089		0.4	%	18.21
Colorado Springs	11	139,711	7.4	%	0.8	%	2,785		0.6	%	19.93
Washington, DC-Capitol Riverfront	5	132,113	7.0	%	0.7	%	5,709		1.2	%	43.21
2013	119	1,879,767	100.0	%	10.6	%	56,239		12.1	%	29.92
Baltimore/Washington Corridor	52	855,086	39.0	%	4.8	%	24,380		5.2	%	28.51
Northern Virginia	8	465,652	21.2	%	2.6	%	14,195		3.0	%	30.48
Greater Baltimore	38	307,834	14.0	%	1.7	%	5,784		1.2	%	18.79
Suburban Maryland	4	88,166	4.0	%	0.5	%	1,811		0.4	%	20.54
St. Mary’s and King George Cos.	12	84,068	3.8	%	0.5	%	1,639		0.4	%	19.49
Colorado Springs	11	183,570	8.4	%	1.0	%	3,604		0.8	%	19.63
Washington, DC-Capitol Riverfront	6	70,200	3.2	%	0.4	%	3,112		0.7	%	44.33
Other	1	138,466	6.3	%	0.8	%	3,454		0.7	%	24.95
2014	132	2,193,042	100.0	%	12.3	%	57,979		12.4	%	26.44
Baltimore/Washington Corridor	54	1,214,738	42.6	%	6.8	%	34,331		7.4	%	28.26
Northern Virginia	12	704,532	24.7	%	4.0	%	21,289		4.6	%	30.22
Greater Baltimore	31	358,531	12.6	%	2.0	%	6,590		1.4	%	18.38
Suburban Maryland	5	146,275	5.1	%	0.8	%	2,944		0.6	%	20.13
St. Mary’s and King George Cos.	8	76,199	2.7	%	0.4	%	1,332		0.3	%	17.48
Greater Philadelphia	1	219,065	7.7	%	1.2	%	2,884		0.6	%	13.17
Colorado Springs	9	104,408	3.7	%	0.6	%	1,998		0.4	%	19.13
Washington, DC-Capitol Riverfront	3	30,599	1.1	%	0.2	%	1,388		0.3	%	45.37
2015	123	2,854,347	100.0	%	16.1	%	72,757		15.6	%	25.49
Baltimore/Washington Corridor	114	3,161,209	39.8	%	17.8	%	83,283		17.9	%	26.35
Northern Virginia	32	807,198	10.2	%	4.5	%	25,347		5.4	%	31.40
Greater Baltimore	80	1,667,756	21.0	%	9.4	%	39,170		8.4	%	23.49
Suburban Maryland	5	223,223	2.8	%	1.3	%	5,254		1.1	%	23.54
St. Mary’s and King George Cos.	6	69,961	0.9	%	0.4	%	1,407		0.3	%	20.11
Greater Philadelphia	2	174,238	2.2	%	1.0	%	4,319		0.9	%	24.79
Colorado Springs	14	657,937	8.3	%	3.7	%	13,763		3.0	%	20.92
San Antonio	6	837,070	10.5	%	4.7	%	24,575		5.3	%	29.36
Washington, DC-Capitol Riverfront	5	48,793	0.6	%	0.3	%	2,176		0.5	%	44.59
Other	2	295,842	3.7	%	1.7	%	8,856		1.9	%	29.94
Thereafter	266	7,943,227	100.0	%	44.7	%	208,150		44.7	%	26.20
Total / Average	843	17,778,581			100.0	%	$	465,767	100.0	%	$	26.20

NOTE: As of September 30, 2011, the weighted average lease term for the wholly owned office properties is 4.8 years.

(1)This expiration analysis includes the effect of early renewals completed on existing leases but excludes the effect of new tenant leases on 356,221 square feet yet to commence as of September 30, 2011.

(2)Many of our government leases are subject to certain early termination provisions which are customary to government leases. The year of lease expiration was computed assuming no exercise of such early termination rights.

(3)Total Annualized Rental Revenue is the monthly contractual base rent as of September 30, 2011 multiplied by 12 plus the estimated annualized expense reimbursements under existing office leases.

17

Third Quarter 2011

Top 20 Tenants (1)

(Based on Annualized Rental Revenue of

wholly owned office properties, dollars in thousands)

			Percentage of		Total		Percentage		Weighted
		Total	Total		Annualized		of Total		Average
	Number of	Occupied	Occupied		Rental		Annualized Rental		Remaining
Tenant	Leases	Square Feet	Square Feet		Revenue (2)		Revenue		Lease Term (3)
United States of America (4)	79	3,257,589	18.3	%	$	101,325	21.8	%	5.5
Northrop Grumman Corporation (5)	16	1,204,210	6.8	%	32,069		6.9	%	6.4
Booz Allen Hamilton, Inc.	9	806,352	4.5	%	24,897		5.3	%	4.4
Computer Sciences Corporation (5)	9	756,351	4.3	%	22,634		4.9	%	2.5
The MITRE Corporation	4	284,819	1.6	%	8,379		1.8	%	5.3
ITT Corporation (5)	9	332,490	1.9	%	8,220		1.8	%	4.3
Wells Fargo & Company (5)	6	214,982	1.2	%	7,798		1.7	%	6.7
The Aerospace Corporation	3	254,869	1.4	%	7,729		1.7	%	3.4
L-3 Communications Holdings, Inc. (5)	4	258,192	1.5	%	7,542		1.6	%	2.5
CareFirst, Inc.	2	222,610	1.3	%	7,247		1.6	%	10.0
General Dynamics Corporation (5)	7	238,130	1.3	%	6,849		1.5	%	4.4
Kratos Defense & Security Solution, Inc. (5)	4	241,627	1.4	%	6,590		1.4	%	8.4
The Boeing Company (5)	6	196,939	1.1	%	6,067		1.3	%	3.0
Comcast Corporation (5)	6	304,732	1.7	%	5,629		1.2	%	7.4
AT&T Corporation (5)	4	315,353	1.8	%	5,527		1.2	%	7.2
Ciena Corporation	5	270,215	1.5	%	5,140		1.1	%	1.5
Raytheon Company	6	180,385	1.0	%	5,097		1.1	%	3.0
Unisys Corporation	1	156,695	0.9	%	3,898		0.8	%	8.7
The Johns Hopkins Institutions (5)	5	141,403	0.8	%	3,709		0.8	%	5.1
Merck & Co., Inc.	2	225,894	1.3	%	3,050		0.7	%	3.7
Subtotal Top 20 Office Tenants	187	9,863,837	55.5	%	279,395		60.0	%	5.2
All remaining tenants	656	7,914,744	44.5	%	186,372		40.0	%	4.3
Total/Weighted Average	843	17,778,581	100.0	%	$	465,767	100.0	%	4.8

(1)Table excludes owner occupied leasing activity which represents 164,956 square feet with total annualized rental revenue of $4.3 million, and a weighted average remaining lease term of 4.5 years as of September 30, 2011.

(2)Total Annualized Rental Revenue is the monthly contractual base rent as of September 30, 2011, multiplied by 12, plus the estimated annualized expense reimbursements under existing office leases.

(3)The weighting of the lease term was computed using Total Rental Revenue.

(4)Many of our government leases are subject to early termination provisions which are customary to government leases. The weighted average remaining lease term was computed assuming no exercise of such early termination rights.

(5)Includes affiliated organizations or agencies.

18

Third Quarter 2011

Real Estate Revenues* by Region

(dollars in thousands)

	Three Months Ended										Nine Months Ended
Office Properties:	9/30/11		6/30/11		3/31/11		12/31/10		9/30/10		9/30/11		9/30/10
Baltimore/Washington Corridor	$	54,744	$	52,860	$	53,252	$	52,829	$	51,946	$	160,856	$	154,627
Northern Virginia	18,640		18,445		18,274		19,283		18,949		55,359		55,780
Greater Baltimore	18,193		17,846		17,612		18,870		18,288		53,651		52,980
Colorado Springs	6,037		5,912		5,920		6,235		6,176		17,869		18,662
Suburban Maryland	5,648		5,325		5,609		5,235		5,243		16,582		16,524
St. Mary’s and King George Counties	3,508		3,564		3,534		3,417		3,431		10,606		10,550
San Antonio	7,701		7,089		7,663		7,898		5,609		22,453		13,775
Washington, DC - Capitol Riverfront	4,507		4,252		4,590		4,543		135		13,349		135
Greater Philadelphia	1,701		1,675		1,939		1,794		1,793		5,315		4,505
Wholesale Data Center	1,283		1,276		1,210		900		162		3,769		162
Other	3,167		2,562		2,838		2,709		3,296		8,567		10,315
Real estate revenues	$	125,129	$	120,806	$	122,441	$	123,713	$	115,028	$	368,376	$	338,015

NOI* by Region

(dollars in thousands)

	Three Months Ended												Nine Months Ended
Office Properties:	9/30/11		6/30/11		3/31/11		12/31/10			9/30/10			9/30/11		9/30/10
Baltimore/Washington Corridor	$	34,839	$	34,535	$	31,862	$	33,442		$	33,001		$	101,236	$	96,674
Northern Virginia	11,276		11,071		10,603		12,382			11,754			32,950		34,566
Greater Baltimore	10,572		10,577		9,072		11,528			10,460			30,221		28,831
Colorado Springs	3,464		3,835		3,484		4,026			3,796			10,783		11,734
Suburban Maryland	3,627		3,091		2,891		3,096			2,625			9,609		9,006
St. Mary’s and King George Counties	2,365		2,594		2,518		2,377			2,279			7,477		7,250
San Antonio	3,804		3,881		3,794		3,877			2,912			11,479		7,349
Washington, DC - Capitol Riverfront	2,699		2,595		2,963		2,835			85			8,257		85
Greater Philadelphia	1,239		1,300		1,493		1,315			1,561			4,032		2,710
Wholesale Data Center	229		445		504		(51		)	(89		)	1,178		(89		)
Other	2,303		1,428		2,352		1,867			2,340			6,083		7,155
NOI	$	76,417	$	75,352	$	71,536	$	76,694		$	70,724		$	223,305	$	205,271

*Includes continuing and discontinued operations.

19

Third Quarter 2011

Same Office Properties (1) Average Occupancy Rates by Region

	Number	Rentable
	of	Square	Three Months Ended										Nine Months Ended
	Buildings	Feet	9/30/11		6/30/11		3/31/11		12/31/10		9/30/10		9/30/11		9/30/10
Baltimore Washington Corridor	97	7,938,756	89.4	%	89.0	%	89.0	%	88.8	%	88.8	%	89.1	%	89.0	%
Northern Virginia	14	2,446,678	89.4	%	88.9	%	87.7	%	91.0	%	91.1	%	88.7	%	96.2	%
Greater Baltimore	34	2,416,859	86.1	%	86.7	%	87.1	%	87.6	%	88.2	%	86.6	%	88.3	%
Suburban Maryland	3	362,387	92.8	%	91.8	%	91.8	%	92.0	%	87.9	%	92.1	%	85.8	%
St.Mary’s and King George Counties	12	585,699	96.9	%	97.7	%	97.7	%	96.4	%	98.4	%	97.4	%	98.6	%
Colorado Springs	18	1,266,214	86.8	%	86.5	%	86.5	%	86.7	%	85.5	%	86.6	%	86.7	%
San Antonio	6	665,117	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%
Greater Philadelphia	1	219,065	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%
Other	2	295,842	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%
Total Office	187	16,196,617	89.8	%	89.6	%	89.5	%	89.9	%	89.9	%	89.7	%	90.6	%
Total Same Office Properties occupancy as of period end			90.0	%	89.8	%	89.1	%	89.8	%	90.1	%

(1)  Same office properties represent buildings owned and 100% operational since January 1, 2010, excluding properties held for future disposition.

20

Third Quarter 2011

Same Office Property Real Estate Revenues by Region

(dollars in thousands)

	Three Months Ended										Nine Months Ended
Office Properties:	9/30/11		6/30/11		3/31/11		12/31/10		9/30/10		9/30/11		9/30/10
Baltimore/Washington Corridor	$	49,738	$	48,220	$	49,255	$	49,529	$	49,098	$	147,213	$	148,690
Northern Virginia	16,528		16,887		16,420		17,418		16,955		49,835		52,374
Greater Baltimore	12,788		12,950		12,967		12,975		13,785		38,705		39,920
Colorado Springs	5,521		5,461		5,316		5,862		5,622		16,298		17,131
Suburban Maryland	2,938		2,673		2,940		2,553		2,390		8,551		7,224
St. Mary’s and King George Counties	2,935		3,008		2,957		2,827		2,754		8,900		8,433
San Antonio	5,855		5,250		5,869		5,964		5,039		16,974		13,205
Greater Philadelphia	707		715		506		741		825		1,928		2,045
Other	2,377		2,150		2,437		2,513		2,551		6,964		7,565
Real estate revenues	$	99,387	$	97,314	$	98,667	$	100,382	$	99,019	$	295,368	$	296,587

Same Office Property NOI by Region

(dollars in thousands)

	Three Months Ended															Nine Months Ended
Office Properties:	9/30/11			6/30/11			3/31/11			12/31/10			9/30/10			9/30/11			9/30/10
Baltimore/Washington Corridor	$	31,496		$	31,293		$	29,348		$	31,106		$	31,087		$	92,137		$	93,498
Northern Virginia	9,953			10,413			9,469			11,145			10,186			29,835			32,135
Greater Baltimore	7,411			7,784			7,280			7,935			8,283			22,475			22,883
Colorado Springs	3,530			3,766			3,375			4,085			3,734			10,671			11,479
Suburban Maryland	2,284			1,721			1,880			1,637			1,417			5,885			4,279
St. Mary’s and King George Counties	2,051			2,256			2,171			2,002			1,812			6,478			5,784
San Antonio	2,365			2,408			2,355			2,402			2,398			7,128			6,919
Greater Philadelphia	669			680			457			713			763			1,806			1,956
Other	2,094			1,920			2,211			2,179			2,192			6,225			6,479
NOI	$	61,853		$	62,241		$	58,546		$	63,204		$	61,872		$	182,640		$	185,412
Add (less): Straight-line rent adjustments	1,882			(1,494		)	(2,937		)	(1,201		)	1,970			(2,549		)	(1,768		)
Less: Amortization of deferred market rental revenue	(197		)	(194		)	(240		)	(280		)	(281		)	(631		)	(943		)
Add: Amortization of above-market cost arrangements	329			329			328			337			337			986			1,011
Same office property cash NOI	$	63,867		$	60,882		$	55,697		$	62,060		$	63,898		$	180,446		$	183,712
Less: Lease termination fees, gross	(130		)	(46		)	(137		)	(945		)	(109		)	(313		)	(1,175		)
Same office property cash NOI, excluding gross lease termination fees	$	63,737		$	60,836		$	55,560		$	61,115		$	63,789		$	180,133		$	182,537

Note:  Same office properties represent buildings owned and 100% operational since January 1, 2010, excluding properties held for future disposition.

21

Third Quarter 2011

Acquisition Summary for Wholly Owned Operating Office Properties  - Nine Months Ended September 30, 2011

				Acquisition	Allocated Contractual Sale
Location	Property Region	Business Park/Submarket	Square Feet	Date	Price (in thousands)
310 The Bridge Street	Other	Huntsville	138,466	8/9/11	$	33,413

Disposition Summary for Wholly Owned Operating Office Properties  — Nine Months Ended September 30, 2011

				Disposition	Allocated Contractual Sale
Location	Property Region	Business Park/Submarket	Square Feet	Date	Price (in thousands)
1344 & 1348 Ashton Road and 1350 Dorsey Road	Baltimore/Washington Corridor	Commons/Parkway	38,954	5/24/11	$	3,800
Subtotal - Quarter Ended 6/30/11			38,954		3,800
216 Schilling Circle	Suburban Baltimore	Hunt Valley Business Center	35,806	8/23/11	4,700
Towson Portfolio	Suburban Baltimore	Towson	178,666	9/29/11	16,000
Subtotal - Quarter Ended 9/30/11			214,472		20,700
Total			253,426		$	24,500

22

Third Quarter 2011

Construction, Pre-Construction, Future Projects, Redevelopment and Controlled Land Summary

(dollars in thousands)

	Rentable Square Feet
	Listed		Listed		Listed		Listed		Listed		Listed
	Construction		Pre-Construction		Future		Redevelopment		Wholesale Data		Controlled
	Projects		Projects		Projects		Projects		Center		Land		Other			Total
Baltimore/Washington Corridor	434,635		140,000		245,000		—		N/A		3,709,000		—			4,528,635
Northern Virginia	236,685		239,000		—		183,440		N/A		1,798,000		—			2,457,125
Greater Baltimore	207,692		—		—		—		N/A		3,032,000		—			3,239,692
Colorado Springs	—		—		—		—		N/A		2,499,000		—			2,499,000
Suburban Maryland	—		—		—		—		N/A		1,900,000		—			1,900,000
St. Mary’s and King George Counties	82,842		—		—		—		N/A		124,000		—			206,842
San Antonio	94,961		—		125,000		—		N/A		1,127,000		—			1,346,961
Greater Philadelphia	—		—		—		113,800		N/A		790,000		—			903,800
Huntsville, Alabama	114,891		63,000		120,000		—		N/A		4,302,000		—			4,599,891
Other	—		—		—		—		N/A		967,000		—			967,000
	1,171,706		442,000		490,000		297,240		N/A		20,248,000		—			22,648,946
	Costs to date, by region
	Listed		Listed		Listed		Listed		Listed		Listed
	Construction		Pre-Construction		Future		Redevelopment		Wholesale Data		Controlled
	Projects (1)		Projects (1)		Projects		Projects (1)		Center (1)		Land		Other			Total
Baltimore/Washington Corridor	$	68,200	$	8,540	$	17,259	$	—	$	—	$	85,474	$	11,276		$	190,749
Northern Virginia	33,886		8,601		—		46,496		—		42,359		—			131,342
Greater Baltimore	31,112		—		—		—		—		82,608		181			113,901
Colorado Springs	—		—		—		—		—		48,379		—			48,379
Suburban Maryland	—		—		—		—		—		24,417		241			24,658
St. Mary’s and King George Counties	15,865		—		—		—		—		3,397		—			19,262
San Antonio	11,325		—		3,413		—		—		22,616		5,406			42,760
Greater Philadelphia	—		—		—		8,568		—		20,689		1,573			30,830
Huntsville, Alabama	8,471		207		1,580		—		—		13,254		—			23,512
Wholesale Data Center	—		—		—		—		191,180		—		—			191,180
Other	—		—		—		—		—		8,381		(148		)	8,233
	$	168,859	$	17,348	$	22,252	$	55,064	$	191,180	$	351,574	$	18,529		$	824,806
	Costs to date, by Balance Sheet line item
	Listed		Listed		Listed		Listed		Listed		Listed
	Construction		Pre-Construction		Future		Redevelopment		Wholesale Data		Controlled
	Projects		Projects		Projects		Projects		Center		Land		Other			Total
Operating properties	$	15,182	$	—	$	3,969	$	45,557	$	44,599	$	15,551	$	—		$	124,858
Land - development	19,561		8,565		6,993		—		5,040		208,786		—			248,945
Properties under construction and development, excluding associated land costs	132,545		8,783		11,290		8,072		141,541		127,209		18,529			447,969
Deferred leasing costs	1,571		—		—		1,435		—		28		—			3,034
	$	168,859	$	17,348	$	22,252	$	55,064	$	191,180	$	351,574	$	18,529		$	824,806

(1) Including cost of land undergoing construction, pre-construction or redevelopment activities.

23

Third Quarter 2011

Controlled Land (1)

Location	Submarket	Status	Acres		Estimated Developable Square Feet
National Business Park - North	BWI Airport	Wholly owned	170		1,405,000
National Business Park - South	BWI Airport	Wholly owned	7		260,000
1243 Winterson Road (AS 22)	BWI Airport	Wholly owned	2		30,000
940 Elkridge Landing Road (AS 7)	BWI Airport	Wholly owned	3		54,000
West Nursery Road	BWI Airport	Wholly owned	1		5,000
Arundel Preserve	BWI Airport	Consolidated JV- 50% interest/Under contract	56	up to	1,382,000
1460 Dorsey Road	BWI Airport	Wholly owned	6		60,000
Columbia Gateway Parcel T-11	Howard Co. Perimeter	Wholly owned	14		220,000
7125 Columbia Gateway Drive	Howard Co. Perimeter	Wholly owned	8		266,000
Riverwood	Howard Co. Perimeter	Wholly owned	5		27,000
Total Baltimore / Washington Corridor			272		3,709,000
Westfields Corporate Center	Dulles South	Wholly owned	23		400,000
Westfields - Park Center	Dulles South	Wholly owned	33		674,000
Woodland Park	Herndon	Wholly owned	5		225,000
Patriot Ridge	Springfield	Wholly owned	11		499,000
Total Northern Virginia			72		1,798,000
Canton Crossing	Baltimore	Wholly owned	10		773,000
White Marsh	White Marsh	Wholly owned	152		1,692,000
North Gate Business Park	Harford County	Wholly owned	39		567,000
Total Greater Baltimore			201		3,032,000
Thomas Johnson Drive	Frederick	Wholly owned	6		170,000
Route 15 / Biggs Ford Road	Frederick	Wholly owned	107		1,000,000
Rockville Corporate Center	Rockville	Wholly owned	10		220,000
M Square Research Park	College Park	Consolidated JV- 50% interest/Under contract	49		510,000
Total Suburban Maryland			172		1,900,000
Arborcrest	Blue Bell	Wholly owned	8		790,000
Total Greater Philadelphia			8		790,000
Dahlgren Technology Center	King George County	Wholly owned	38		64,000
Expedition VII	St. Mary’s County	Wholly owned	6		60,000
Total St. Mary’s & King George Counties			44		124,000
InterQuest	I-25 North Corridor	Wholly owned	113		1,623,000
9965 Federal Drive	I-25 North Corridor	Wholly owned	4		30,000
Patriot Park	Colorado Springs East	Wholly owned	71		756,000
Aerotech Commerce	Colorado Springs East	Wholly owned	6		90,000
Total Colorado Springs			194		2,499,000
Northwest Crossroads	San Antonio Northwest	Wholly owned	31		375,000
Military Drive	San Antonio Northwest	Wholly owned	41		752,000
Total San Antonio			72		1,127,000
Redstone Gateway	Huntsville, AL	Consolidated JV - 85% interest/Under contract	443		4,302,000
Total Huntsville			443		4,302,000
Indian Head	Charles County, MD	Consolidated JV - 75% interest	208		967,000
Fort Ritchie	Fort Ritchie	Wholly owned	591		—
Total Other			799		967,000
TOTAL			2,276		20,248,000

(1)This land inventory schedule excludes all properties listed as construction, redevelopment, pre-construction or future projects as detailed on pages 25 and 26, and includes properties under ground lease to us.

24

Third Quarter 2011

Summary of Construction and Redevelopment Projects

(dollars in thousands)

																				Actual or
			Total		Percentage		as of September 30, 2011 (1)													Anticipated
			Rentable		Leased		Anticipated								Cost to					Construction	Anticipated
	Park/		Square		as of		total				Cost				date placed					Completion	Operational
Property and Location	Submarket	Ownership	Feet		9/30/11		cost				to date				in service					Date (2)	Date (3)
Construction
316 Sentinel Way (316 NBP) Annapolis Junction, Maryland	BWI Airport	Wholly owned	125,150		63	%	$			32,400	$			23,136	—					1Q 11	1Q 12
7205 Riverwood Road Columbia, Maryland	Howard Co. Perimeter	Wholly owned	89,295		0	%	22,025				12,775				—					4Q 11	4Q 12
Subtotal Government			214,445		37	%	$	54,425			$		35,911		$			—
% of Total Drivers			18	%
410 National Business Parkway Annapolis Junction, Maryland	BWI Airport	Wholly owned	110,362		0	%	$			25,643	$			14,331	—					4Q 11	4Q 12
430 National Business Parkway Annapolis Junction, Maryland (4)	BWI Airport	Wholly owned	109,828		61	%	24,291				17,958				4,972					2Q 11	2Q 12
7770 Backlick Road (Patriot Ridge) Springfield, Virginia	Springfield	Wholly owned	236,685		0	%	77,172				33,886				—					2Q 12	2Q 13
206 Research Boulevard Aberdeen, Maryland	Harford County	Wholly owned	128,119		0	%	25,824				17,033				—					3Q 11	3Q 12
210 Research Boulevard Aberdeen, Maryland (5)	Harford County	Wholly owned	79,573		35	%	17,304				14,079				6,228					4Q 10	4Q 11
45310 Abell House Lane California, Maryland	St. Mary’s County	Wholly owned	82,842		100	%	18,080				15,865				—					3Q 11	4Q 11
100 Sentry Gateway San Antonio, Texas	San Antonio Northwest	Wholly owned	94,961		0	%	15,433				11,325				—					4Q 10	4Q 11
1000 Redstone Gateway Huntsville, Alabama	Huntsville	Consolidated Joint Venture	114,891		0	%	21,231				8,471				—					4Q 11	4Q 12
Subtotal Defense Information Technology			957,261		19	%	$		224,978		$			132,948	$		11,200
% of Total Drivers			82	%
Total Under Construction			1,171,706		22	%	$	279,403			$			168,859	$	11,200
Redevelopment
3120 Fairview Park Drive Herndon, Virginia  (6)	Herndon	Wholly owned	183,440		36	%	$			57,800	$			46,496	$		46,496			4Q10	4Q11
751 Arbor Way (Hillcrest I) Blue Bell, Pennsylvania	Philadelphia	Wholly owned	113,800		25	%	20,400				8,568				—					4Q 11	4Q 12
Total Redevelopment			297,240				$		78,200		$	55,064			$				46,496

(1)	Cost includes land, construction, leasing costs and allocated portion of structured parking and other shared infrastructure, if applicable.
(2)	Actual or anticipated construction completion date is the estimated date of completion of the building shell.
(3)	Anticipated operational date is the estimated date when leases have commenced on 100% of a property’s space or one year from the cessation of major construction activities.
(4)	Although classified as “Under Construction,” 61,299 square feet are operational.
(5)	Although classified as “Under Construction,” 27,551 square feet are operational.
(6)	This property was shell complete in 2008 and we acquired in December 2010. For accounting purposes, this space was 100% operational upon acquisition. For occupancy reporting, we are including the space as “Redevelopment” until the earlier of when leases commence or one year from the date of acquisition. 42,910 square feet are operational.

Demand Driver Categories (as classified by COPT management):

· Defense Information Technology: Development opportunity created through our current and future relationships with defense information technology contractors and, possibly, minor Government tenancy.

· Government: Development opportunity created through our existing and future relationship with various agencies of the government of the United States of America. Excludes Government tenancy included in Defense Information Technology.

· Market Demand: Development opportunity created through perceived unfulfilled space requirements within a specific submarket; potential submarket demand exceeds existing supply.

· Research Park: Development opportunity created through specific research park relationship.

25

Third Quarter 2011

Summary of Pre-Construction and Future Projects

(dollars in thousands)

			Total	Percentage	as of September 30, 2011 (1)
			Rentable	Leased	Anticipated
	Park/		Square	as of	total			Cost
Property and Location	Submarket	Ownership	Feet	9/30/11	cost			to date
Pre-Construction: Leasing-Contingent Starts in 2012
420 National Business Parkway Annapolis Junction, Maryland	BWI Airport	Wholly owned	140,000	N/A	$	35,500		$	8,540
7800 Backlick Road (Patriot Ridge) Springfield, Virginia	Springfield	Wholly owned	239,000	N/A	71,000			8,601
7200 Redstone Gateway (Flex) Huntsville, Alabama	Huntsville	Consolidated Joint Venture	63,000	N/A	8,000			207
Total Pre-Construction - All Defense Information Technology			442,000		$		114,500	$		17,348
Future Projects
312 Sentinel Way Annapolis Junction, Maryland	BWI Airport	Wholly owned	125,000
8100 Potranco Road San Antonio, Texas	San Antonio Northwest	Wholly owned	125,000
Subtotal Government			250,000
1200 Redstone Gateway (Building 2) Huntsville, Alabama	Huntsville	Consolidated Joint Venture	120,000
560 National Business Parkway Annapolis Junction, Maryland	BWI Airport	Wholly owned	120,000
Subtotal Defense Information Technology			240,000
Total Future Projects			490,000

(1) Cost includes land, construction, leasing costs and allocated portion of structured parking and other shared infrastructure, if applicable.

Demand Driver Categories (as classified by COPT management):

· Defense Information Technology:  Development opportunity created through our current and future relationships with defense information technology contractors and, possibly, minor  Government tenancy.

· Government:  Development opportunity created through our existing and future relationship with various agencies of the government of the United States of America.  Excludes Government tenancy included in Defense Information Technology.

· Market Demand:  Development opportunity created through perceived unfulfilled space requirements within a specific submarket; potential submarket demand exceeds existing supply.

· Research Park:  Development opportunity created through a specific research park relationship.

26

Third Quarter 2011

Office Property Construction Placed into Service in 2011 (1)

			Total
			Rentable
			Square Feet
			Upon	Construction Square Feet Placed into Service
	Business Park/		Construction			Year 2011			As of September 30, 2011 (2)
Property and Location	Submarket	Ownership	Completion	Year 2010	1st Quarter	2nd Quarter	3rd Quarter	Total	Occupied %		Leased %
209 Research Boulevard Aberdeen, Maryland	Harford County	Wholly owned	77,192	47,930	6,097	23,165	—	77,192	93	%	100	%
308 Sentinel Drive (308 NBP) Annapolis Junction, Maryland	BWI Airport	Wholly owned	151,207	31,127	120,080	—	—	151,207	98	%	100	%
430 National Business Parkway Annapolis Junction, Maryland	BWI Airport	Wholly owned	109,828	—	—	—	61,299	61,299	56	%	61	%
Total Construction Placed Into Service			338,227	79,057	126,177	23,165	61,299	289,698

(1) Includes construction properties with space placed into service in 2011.

(2) Represents occupancy and leasing percentages of square feet placed into service.

27

Third Quarter 2011

Construction Leasing Trend Analysis Over Previous Five Quarters (1)

			Total
			Rentable	Construction
			Square	Commencement	Cumulative Square Feet Leased as of
Property and Location	Submarket	Ownership	Feet	Date	9/30/2010		12/31/2010		3/31/2011		6/30/2011		9/30/2011
316 Sentinel Way (316 NBP) Annapolis Junction, Maryland	BWI Airport	Wholly owned	125,150	1Q 10	—		—		—		—		78,820
324 Sentinel Way (324 NBP) Annapolis Junction, Maryland	BWI Airport	Wholly owned	125,118	1Q 09	125,118		125,118		125,118		125,118		125,118
7205 Riverwood Road Columbia, Maryland	Howard Co. Perimeter	Wholly owned	89,295	4Q 10	—		—		—		—		—
8000 Potranco Road San Antonio, Texas	San Antonio Northwest	Wholly owned	125,157	1Q 09	125,157		125,157		125,157		125,157		125,157
8030 Potranco Road San Antonio, Texas	San Antonio Northwest	Wholly owned	125,155	1Q 09	125,155		125,155		125,155		125,155		125,155
Subtotal Government			589,875		375,430		375,430		375,430		375,430		454,250
					64	%	64	%	64	%	64	%	77	%
300 Sentinel Drive (300 NBP) Annapolis Junction, Maryland	BWI Airport	Wholly owned	193,296	1Q 08	155,930		166,872		190,529		190,529		190,529
308 Sentinel Drive (308 NBP) Annapolis Junction, Maryland	BWI Airport	Wholly owned	151,207	3Q 09	148,482		148,482		148,482		151,207		151,207
410 National Business Parkway Annapolis Junction, Maryland	BWI Airport	Wholly owned	110,362	4Q 10	—		—		—		—		—
430 National Business Parkway Annapolis Junction, Maryland	BWI Airport	Wholly owned	109,828	3Q 10	—		—		—		61,299		67,065
7770 Backlick Road (Patriot Ridge) Springfield, Virginia	Springfield	Wholly owned	236,685	1Q 11	—		—		—		—		—
206 Research Boulevard Aberdeen, Maryland	Harford County	Wholly owned	128,119	3Q 10	—		—		—		—		—
209 Research Boulevard Aberdeen, Maryland	Harford County	Wholly owned	77,192	1Q 09	77,192		77,192		77,192		77,192		77,192
210 Research Boulevard Aberdeen, Maryland	Harford County	Wholly owned	79,573	4Q 09	27,551		27,551		27,551		27,551		27,551
10807 New Allegiance Drive Colorado Springs, Colorado	1-25 North Corridor	Wholly owned	145,723	2Q 08	59,993		59,993		59,993		59,993		59,993
565 Space Center Drive (Patriot Park) Colorado Springs, Colorado	Colorado Springs East	Wholly owned	89,899	2Q 08	1,949		1,949		1,949		1,949		1,949
45310 Abell House Lane (2) California, MD	St. Mary’s County	Wholly owned	82,842	4Q 10	82,842		82,842		82,842		82,842		82,842
100 Sentry Gateway San Antonio, Texas	San Antonio Northwest	Wholly owned	94,961	1Q 10	—		—		—		—		—
1000 Redstone Gateway Huntsville, Alabama	Huntsville	Consolidated Joint Venture	114,891	1Q 11	—		—		—		—		—
Subtotal Defense Information Technology			1,614,578		553,939		564,881		588,538		652,562		658,328
					34	%	35	%	36	%	40	%	41	%
Total Construction Leasing			2,204,453		929,369		940,311		963,968		1,027,992		1,112,578
Percent Leased					42	%	43	%	44	%	47	%	50	%

(1) Includes office properties not included in same office that were under active construction as of period end or for which construction was recently completed.

(2) We acquired this property in August 2010.

28

Third Quarter 2011

Wholesale Data Center Summary

(dollars in thousands)

Initial

Critical Load

Raised Floor

Stabilization

Upon

Anticipated

Cash NOI for

Cash NOI for

Gross Building

Square

Critical Load

Completion

MW

Total

Cost

Three Months

Nine Months

Property and Location

Area

Footage (1)

(in MWs) (2)

Leased

Operational

Cost (3)

to date

Ended 9/30/11

Ended 9/30/11

Power Loft @ Innovation

9651 Hornbaker Road

Manassas, Virginia

233,000

100,000

18

17

%

17

%

$

275,230

$

191,180

$

137

$

874

Lease Expiration Analysis

					Total
	Number				Annual Rental
	of Leases	Raised Floor	Critical Load	Critical Load	Revenue of
Year of Lease Expiration	Expiring	Square Footage	Leased (MW)	Used (MW)	Expiring Leases
2019	1	7,172	1	1	$	2,057
2020	1	19,023	2	1	2,084
			3	2	$	4,141

(1) Raised floor square footage is that portion of the gross building area where tenants locate their computer servers. Raised floor area is considered to be the net rentable square footage.

(2) Critical load is the power available for exclusive use of tenants in the property (expressed in terms of megawatts (“MWs”)).

(3) Anticipated total cost includes land, construction and leasing costs.

29

Third Quarter 2011

Quarterly Common Equity Analysis

(Dollars and shares in thousands, except per share amounts)

			As if Converted		Diluted
SHAREHOLDER CLASSIFICATION	Common	Common	Preferred		Ownership
As of September 30, 2011:	Shares	Units	Shares/Units	Total	% of Total
Insiders	1,110,811	3,675,966	—	4,786,777	6.22	%
Non-insiders	70,876,125	643,255	610,014	72,129,394	93.78	%
	71,986,936	4,319,221	610,014	76,916,171	100.00	%

	9/30/11			6/30/11			3/31/11			12/31/10			9/30/10
COMMON EQUITY - End of Quarter
Common Shares	71,987			71,892			67,104			66,932			59,406
Common Units	4,319			4,382			4,386			4,403			4,446
Total	76,306			76,273			71,490			71,334			63,852
End of Quarter Common Share Price	$	21.78		$	31.11		$	36.14		$	34.95		$	37.31
Market Value of Common Shares/Units	$	1,661,948		$	2,372,863		$	2,583,646		$	2,493,134		$	2,382,318
Common Shares Trading Volume
Average Daily Volume (Shares)	951			779			711			784			728
Average Daily Volume	$	25,589		$	26,322		$	25,009		$	27,910		$	27,241
As a Percentage of Weighted Average Common Shares	1.3		%	1.1		%	1.1		%	1.2		%	1.2		%
Common Share Price Range (price per share)
Quarterly High	$	32.07		$	36.79		$	36.90		$	38.96		$	39.85
Quarterly Low	$	21.75		$	30.63		$	33.83		$	33.33		$	35.04
Quarterly Average	$	27.10		$	33.81		$	35.20		$	35.59		$	37.44

30

Third Quarter 2011

Quarterly Preferred Equity and Total Market Capitalization Analysis

(dollars and shares in thousands, except per share amounts)

	9/30/11		6/30/11		3/31/11		12/31/10		9/30/10
PREFERRED EQUITY
Convertible Preferred Equity - End of Quarter
Convertible Series I Preferred Units Outstanding	352		352		352		352		352
Conversion Ratio	0.5000		0.5000		0.5000		0.5000		0.5000
Common Shares Issued Assuming Conversion	176		176		176		176		176
Convertible Series K Preferred Shares Outstanding	532		532		532		532		532
Conversion Ratio	0.8163		0.8163		0.8163		0.8163		0.8163
Common Shares Issued Assuming Conversion	434		434		434		434		434
Nonconvertible Preferred Equity - End of Quarter
Redeemable Series G Shares Outstanding	2,200		2,200		2,200		2,200		2,200
Redeemable Series H Shares Outstanding	2,000		2,000		2,000		2,000		2,000
Redeemable Series J Shares Outstanding	3,390		3,390		3,390		3,390		3,390
Total Nonconvertible Preferred Equity	7,590		7,590		7,590		7,590		7,590
Convertible Preferred Equity
Convertible Series K Shares Outstanding	884		884		884		884		884
Total Preferred Equity	8,474		8,474		8,474		8,474		8,474
Nonconvertible Preferred Equity ($25 par value)
Redeemable Series G Shares	$	55,000	$	55,000	$	55,000	$	55,000	$	55,000
Redeemable Series H Shares	50,000		50,000		50,000		50,000		50,000
Redeemable Series J Shares	84,750		84,750		84,750		84,750		84,750
Total Nonconvertible Preferred Equity	$	189,750	$	189,750	$	189,750	$	189,750	$	189,750
Convertible Preferred Equity ($25 liquidation value)
Convertible Series I Units	$	8,800	$	8,800	$	8,800	$	8,800	$	8,800
Convertible Preferred Equity ($50 liquidation value)
Convertible Series K Shares	26,583		26,583		26,583		26,583		26,583
Total Convertible Preferred Equity	$	35,383	$	35,383	$	35,383	$	35,383	$	35,383
Total Liquidation Value of Preferred Equity	$	225,133	$	225,133	$	225,133	$	225,133	$	225,133
CAPITALIZATION
Liquidation Value of Preferred Shares/Units	$	225,133	$	225,133	$	225,133	$	225,133	$	225,133
Market Value of Common Shares/Units	1,661,948		2,372,863		2,583,646		2,493,134		2,382,318
Total Equity Market Capitalization	$	1,887,081	$	2,597,996	$	2,808,779	$	2,718,267	$	2,607,451
Total Debt	$	2,420,073	$	2,299,416	$	2,396,795	$	2,323,681	$	2,468,419
Total Market Capitalization	$	4,307,154	$	4,897,412	$	5,205,574	$	5,041,948	$	5,075,870

31

Third Quarter 2011

Dividend Analysis

	Three Months Ended															Nine Months Ended
	9/30/11			6/30/11			3/31/11			12/31/10			9/30/10			9/30/11			9/30/10
Common Share Dividends
Dividends per share/unit	$	0.4125		$	0.4125		$	0.4125		$	0.4125		$	0.4125		$	1.2375		$	1.1975
Increase over prior period	0.0		%	0.0		%	0.0		%	0.0		%	5.1		%	3.3		%	5.3		%
Common Dividend Payout Ratios
Diluted FFO Payout, as adjusted for comparability	80.5		%	75.8		%	79.2		%	61.7		%	71.3		%	78.4		%	73.2		%
Diluted AFFO Payout	94.5		%	104.7		%	117.6		%	84.0		%	78.3		%	104.5		%	81.8		%
Diluted AFFO Payout, as adjusted for recurring capital expenditures of properties included in Strategic Reallocation Plan	87.0		%	90.7		%	93.8		%	84.0		%	78.3		%	90.3		%	81.8		%
Dividend Coverage - Diluted FFO, as adjusted for comparability	1.24		x	1.32		x	1.26		x	1.62		x	1.40		x	1.28		x	1.37		x
Dividend Coverage - Diluted AFFO	1.06		x	0.95		x	0.85		x	1.19		x	1.28		x	0.96		x	1.22		x
Common Dividend Yields
Dividend Yield at Quarter End	7.58		%	5.30		%	4.57		%	4.72		%	4.42		%
Series I Preferred Unit Distributions
Preferred Unit Distributions Per Unit	$	0.46875		$	0.46875		$	0.46875		$	0.46875		$	0.46875
Preferred Unit Distributions Yield	7.500		%	7.500		%	7.500		%	7.500		%	7.500		%
Quarter End Recorded Book Value	$	25.00		$	25.00		$	25.00		$	25.00		$	25.00
Series G Preferred Share Dividends
Preferred Share Dividends Per Share	$	0.50000		$	0.50000		$	0.50000		$	0.50000		$	0.50000
Preferred Share Dividend Yield	8.000		%	8.000		%	8.000		%	8.000		%	8.000		%
Quarter End Recorded Book Value	$	25.00		$	25.00		$	25.00		$	25.00		$	25.00
Series H Preferred Share Dividends
Preferred Share Dividends Per Share	$	0.46875		$	0.46875		$	0.46875		$	0.46875		$	0.46875
Preferred Share Dividend Yield	7.500		%	7.500		%	7.500		%	7.500		%	7.500		%
Quarter End Recorded Book Value	$	25.00		$	25.00		$	25.00		$	25.00		$	25.00
Series J Preferred Share Dividends
Preferred Share Dividends Per Share	$	0.47656		$	0.47656		$	0.47656		$	0.47656		$	0.47656
Preferred Share Dividend Yield	7.625		%	7.625		%	7.625		%	7.625		%	7.625		%
Quarter End Recorded Book Value	$	25.00		$	25.00		$	25.00		$	25.00		$	25.00
Series K Preferred Share Dividends
Preferred Share Dividends Per Share	$	0.70000		$	0.70000		$	0.70000		$	0.70000		$	0.70000
Preferred Share Dividend Yield	5.600		%	5.600		%	5.600		%	5.600		%	5.600		%
Quarter End Recorded Book Value	$	50.00		$	50.00		$	50.00		$	50.00		$	50.00

32

Third Quarter 2011

Debt Analysis

(dollars in thousands)

	9/30/11			6/30/11			3/31/11			12/31/10			9/30/10
Debt Outstanding
Mortgage Loans	$	1,094,937		$	1,373,292		$	1,479,924		$	1,483,913		$	1,447,852
Construction Loans (1)	22,710			191,754			178,365			159,092			138,655
Unsecured Revolving Credit Facility (2)	671,000			342,000			348,000			295,000			498,000
Other Unsecured Debt	405,022			4,995			4,968			1,947			1,965
Exchangeable Senior Notes	226,404			387,375			385,538			383,729			381,947
	$	2,420,073		$	2,299,416		$	2,396,795		$	2,323,681		$	2,468,419
Interest Rate Data
Fixed-Exchangeable Senior Notes	$	226,404		$	387,375		$	385,538		$	383,729		$	381,947
Other Fixed-Rate Debt	1,060,562			1,068,364			1,174,656			1,175,305			1,179,060
Variable Rate Loans	723,710			434,101			426,849			504,712			687,412
Variable Rate Loans Subject to Interest Rate Swaps (3)	409,397			409,576			409,752			259,935			220,000
	$	2,420,073		$	2,299,416		$	2,396,795		$	2,323,681		$	2,468,419
% of Fixed Rate Loans (3)	70.10		%	81.12		%	82.19		%	78.28		%	72.15		%
% of Variable Rate Loans (3)	29.90		%	18.88		%	17.81		%	21.72		%	27.85		%
	100.00		%	100.00		%	100.00		%	100.00		%	100.00		%
	Three Months Ended															Nine Months Ended
	9/30/2011			6/30/2011			3/31/2011			12/31/2010			9/30/2010			9/30/2011		9/30/2010
Average Contract Interest Rates
Mortgage & Construction Loans	5.40		%	5.25		%	5.27		%	5.32		%	5.42		%	5.31	%	5.44	%
Unsecured Revolving Credit Facility (4)	2.39		%	2.13		%	2.18		%	2.07		%	2.19		%	2.23	%	2.16	%
Other Unsecured Debt	2.02		%	0.00		%	0.00		%	0.00		%	0.00		%	1.87	%	0.00	%
Exchangeable Senior Notes (5)	3.96		%	3.95		%	3.95		%	3.95		%	3.95		%	3.95	%	3.86	%
Total Weighted Average	4.69		%	4.88		%	4.91		%	4.92		%	5.06		%	4.83	%	5.05	%
Debt ratios (coverage ratios excluding capitalized interest) — All coverage computations include the effect of discontinued operations
NOI interest coverage ratio	3.35		x	3.18		x	3.01		x	3.20		x	3.00		x	3.18	x	3.05	x
Adjusted EBITDA interest coverage ratio	3.04		x	3.09		x	2.91		x	3.32		x	2.84		x	3.01	x	2.88	x
NOI debt service coverage ratio	2.93		x	2.76		x	2.59		x	2.78		x	2.62		x	2.76	x	2.64	x
Adjusted EBITDA debt service coverage ratio	2.66		x	2.68		x	2.51		x	2.89		x	2.48		x	2.62	x	2.50	x
NOI fixed charge coverage ratio	2.83		x	2.71		x	2.56		x	2.72		x	2.55		x	2.70	x	2.57	x
Adjusted EBITDA fixed charge coverage ratio	2.57		x	2.62		x	2.48		x	2.83		x	2.41		x	2.55	x	2.43	x
Debt to Adjusted EBITDA ratio (6)	8.73		x	7.87		x	8.66		x	7.29		x	9.21		x
Adjusted debt to Adjusted EBITDA ratio (7)	7.03		x	6.39		x	7.23		x	6.08		x	7.93		x

(1)	Effective September 1, 2011, we extinguished our previously existing Revolving Construction Facility that provided for borrowings of up to $225.0 million.
(2)	Effective September 1, 2011, we entered into a new Revolving Credit Facility that replaced our previously existing facility. As of September 30, 2011, our borrowing capacity under the new facility was $1.0 billion, of which $323.1 million was available.
(3)	Includes the effect of interest rate swaps in effect during certain of the periods set forth above that hedge the risk of changes in interest rates on certain of our one-month LIBOR-based variable rate debt.
(4)	Includes effect of interest expense incurred on interest rate swaps.
(5)	Represents the weighted average of the stated interest rates on our Exchangeable Senior Notes.
(6)	Represents debt divided by Adjusted EBITDA for the three month period multiplied by four.
(7)	Represents debt adjusted to subtract construction in progress as of period end divided by Adjusted EBITDA for the three month period multiplied by four.

33

Third Quarter 2011

Debt Maturity Schedule

(dollars in thousands)

													Exchangeable
	Non-Recourse Debt (1)					Recourse Debt (2)							Senior Notes (3)
Year of Maturity	Annual Amortization of Monthly Payments		Balloon Payments Due on Maturity		Weighted Average Interest Rate of Amounts Maturing	Annual Amortization of Monthly Payments		Balloon Payments Due on Maturity		Weighted Average Interest Rate of Amounts Maturing	Revolver (2)		Balloon Payments Due on Maturity		Total Scheduled Payments
October - December	$	3,211	$	—	N/A	$	50	$	—	N/A	$	—	$	—	$	3,261
2012	12,808		36,123			200		16,753			—		—		65,884
2013	10,086		134,843			200		5,957			—		—		151,086
2014(4)	6,899		136,681			200		15,000			671,000		—		829,780
2015	5,538		135,734			200		419,000			—		240,000		800,472
2016	3,837		274,605			200		—			—		—		278,642
Thereafter	1,407		300,610			1,850		11			—		—		303,878
	$	43,786	$	1,018,596		$	2,900	$	456,721		$	671,000	$	240,000	$	2,433,003
													Net discount		(12,930		)
													Total Debt		$	2,420,073

Notes:
(1)	Certain mortgages contain extension options, generally either for a period of six months or one year, subject to certain conditions. The maturity dates presented above in the table assume that the extension options have not been exercised.
(2)	As of September 30, 2011, our borrowing capacity under the Revolving Credit Facility was $1.0 billion, of which $323.1 million was available.
(3)	4.25% Exchangeable Senior Notes totaling $240.0 million mature in April 2030 but are subject to a put by the holders in April 2015 and every five years thereafter.
(4)	We have $73.2 million of nonrecourse debt maturing in 2034 that may be prepaid in 2014, subject to certain conditions. The above table includes $69.2 million in maturities on these loans in 2014.

34

Third Quarter 2011

Summary of Consolidated Joint Ventures

(dollars in thousands)

	Operational				Total		Property Level		% COPT
Operating Properties	Square Feet		Occupancy		Assets (1)		Debt		Owned
Baltimore/Washington Corridor:
7740 Milestone Parkway	144,610		6.0	%	$	27,990	$	16,753	50	%
Suburban Maryland:
4230 Forbes Boulevard	55,883		70.3	%	3,988		—		50	%
M Square - operating properties					57,130		39,397		50	%
5825 University Research Drive	118,620		79.5	%
5850 University Research Drive	123,449		100.0	%
Total/Average	442,562		60.0	%	$	89,108	$	56,150
NOI of Operating Properties for Three Months Ended September 30, 2011 (2)	$	1,751
NOI of Operating Properties for Nine Months Ended September 30, 2011 (2)	$	4,590
	Estimated
	Developable				Total		Property-Level		% COPT
Non-operational Properties	Square Feet				Assets (1)		Debt		Owned
Baltimore/Washington Corridor:
7742-7874 Milestone Parkway	1,382,000				$	5,492	—		50	%
Suburban Maryland:
Indian Head Technology Center Business Park	967,000				6,524		—		75	%
M Square Research Park	510,000				3,060		—		50	%
Huntsville, AL:
Redstone Gateway	4,302,000				38,854		—		85	%
Total	7,161,000				$	53,930	$	—

(1)	Total assets includes the total assets recorded on the books of the consolidated joint venture plus any outside investment basis related to the applicable joint venture and related joint ventures (formed and to be formed).
(2)	Represents gross NOI of the joint venture operating properties before allocation to joint venture partners.

35

Third Quarter 2011

Summary of Unconsolidated Joint Venture

(dollars in thousands)

	Operational
Property and Location	Square Feet			Occupancy
Greater Harrisburg:
2605 Interstate Drive	79,456			100.0	%
2601 Market Place	65,411			90.0	%
6340 Flank Drive	68,200			100.0	%
6345 Flank Drive	69,443			63.0	%
6360 Flank Drive	46,589			39.1	%
6375 Flank Drive	19,783			71.3	%
6380 Flank Drive	32,668			80.6	%
6385 Flank Drive	32,932			80.7	%
6400 Flank Drive	52,439			26.5	%
6405 Flank Drive	32,000			0.0	%
75 Shannon Road	20,887			0.0	%
85 Shannon Road	12,863			100.0	%
95 Shannon Road	21,976			100.0	%
5035 Ritter Road	56,556			100.0	%
5070 Ritter Road - Building A	31,710			36.4	%
5070 Ritter Road - Building B	28,347			82.0	%
Total/Average	671,260			70.9	%
COPT Investment	$	(5,953	)
Total Assets	$	63,977
Property Level Debt	$	65,007
NOI of Operating Properties for Three Months Ended September 30, 2011 (1)	$	1,001
NOI of Operating Properties for Nine Months Ended September 30, 2011 (1)	$	2,850
% COPT Owned	20		%

(1) Represents gross NOI of the joint venture operating properties before allocation to joint venture partners.

36

Third Quarter 2011

Supplementary Reconciliations of Non-GAAP Measures

(in thousands)

	Three Months Ended															Nine Months Ended
	9/30/11			6/30/11			3/31/11			12/31/10			9/30/10			9/30/11			9/30/10
Net income (loss)	$	7,470		$	(26,007	)	$	(18,566	)	$	16,752		$	8,926		$	(37,103	)	$	28,752
Interest expense on continuing and discontinued operations	25,629			26,830			26,928			26,878			26,626			79,387			75,250
Total income tax (benefit) expense	(457		)	(5,042		)	(544		)	33			27			(6,043		)	86
Depreciation of furniture, fixtures and equipment (FF&E)	614			623			625			642			652			1,862			1,934
Real estate-related depreciation and amortization	36,032			32,049			33,020			35,347			30,745			101,101			87,896
Impairment losses	—			44,605			27,742			—			—			72,347			—
Adjusted EBITDA	$	69,288		$	73,058		$	69,205		$	79,652		$	66,976		$	211,551		$	193,918
Add back:
General and administrative	6,154			6,320			6,777			6,103			6,079			19,251			17,905
Business development	1,050			588			488			691			2,886			2,126			3,506
Depreciation of FF&E	(614		)	(623		)	(625		)	(642		)	(652		)	(1,862		)	(1,934		)
Income from construction contracts and other service operations	(558		)	(1,188		)	(410		)	(483		)	(261		)	(2,156		)	(1,890		)
Interest and other loss (income)	242			(2,756		)	(1,168		)	(7,626		)	(395		)	(3,682		)	(1,942		)
Loss on early extinguishment of debt on continuing and discontinued operations	1,995			25			—			—			—			2,020			—
Gain on sales of operating properties	(1,299		)	(150		)	—			4			(784		)	(1,449		)	(1,081		)
Non-operational property sales	—			(16		)	(2,701		)	—			(2,477		)	(2,717		)	(2,840		)
Equity in loss (income) of unconsolidated entities	159			94			(30		)	(1,005		)	(648		)	223			(371		)
NOI	$	76,417		$	75,352		$	71,536		$	76,694		$	70,724		$	223,305		$	205,271
Discontinued Operations
Revenues from real estate operations	$	3,236		$	3,121		$	3,077		$	4,474		$	3,954		$	9,434		$	12,344
Property operating expenses	(1,057		)	(1,088		)	(1,639		)	(1,268		)	(1,291		)	(3,784		)	(4,413		)
Depreciation and amortization	(313		)	(990		)	(2,078		)	(1,789		)	(1,242		)	(3,381		)	(3,528		)
Interest	(248		)	(330		)	(397		)	(361		)	(452		)	(975		)	(1,208		)
Loss on early extinguishment of debt	(340		)	—			—			—			—			(340		)	—
Impairment losses	—			(14,523		)	—			—			—			(14,523		)	—
Gain (loss) on sales of depreciated real estate properties	1,299			150			—			(4		)	784			1,449			1,081
Discontinued operations	$	2,577		$	(13,660	)	$	(1,037	)	$	1,052		$	1,753		$	(12,120	)	$	4,276
Gain on sales of real estate, net, per statements of operations	$	—		$	16		$	2,701		$	—		$	2,477		$	2,717		$	2,829
Add income taxes	—			—			—			—			—			—			11
Gain (loss) on sales of real estate from discontinued operations	1,299			150			—			(4		)	784			1,449			1,081
Gain (loss) on sales of real estate from continuing and discontinued operations	1,299			166			2,701			(4		)	3,261			4,166			3,921
Less: Gain on sales of non-operating properties	—			(16		)	(2,701		)	—			(2,477		)	(2,717		)	(2,840		)
Gain (loss) on sales of operating properties	$	1,299		$	150		$	—		$	(4	)	$	784		$	1,449		$	1,081
Weighted Average Shares for period ended:
Common Shares Outstanding	71,312			68,446			66,340			63,404			58,656			68,718			58,333
Dilutive effect of share-based compensation awards	52			151			261			236			296			147			367
Common Units	4,336			4,382			4,396			4,412			4,453			4,371			4,674
Denominator for FFO per share - diluted	75,700			72,979			70,997			68,052			63,405			73,236			63,374
Denominator for diluted EPS	71,312			72,828			70,736			63,640			58,952			73,089			58,700
Anti-dilutive EPS effect of share-based compensation awards	52			151			261			—			—			147			—
Weighted average common units	4,336			—			—			4,412			4,453			—			4,674
Denominator for diluted FFO per share	75,700			72,979			70,997			68,052			63,405			73,236			63,374

37

Third Quarter 2011

Supplementary Reconciliations of Non-GAAP Measures (continued)

(dollars in thousands)

	Three Months Ended															Nine Months Ended
	9/30/11			6/30/11			3/31/11			12/31/10			9/30/10			9/30/11			9/30/10
Total Assets or Denominator for Debt to Total Assets	$	3,965,392		$	3,868,230		$	3,865,809		$	3,844,517		$	3,737,372
Accumulated depreciation	553,306			527,616			526,825			503,032			479,218
Accumulated depreciation included in assets held for sale	6,791			6,791			—			—			—
Intangible assets on real estate acquisitions, net	97,954			99,374			106,444			113,735			123,307
Assets other than assets included in properties, net and assets held for sale	(423,408		)	(393,304		)	(397,038		)	(399,062		)	(388,222		)
Non real estate assets included in assets held for sale	(1,946		)	(1,522		)	—			—			—
Denominator for Debt to Undepreciated Book Value of Real Estate Assets	$	4,198,089		$	4,107,185		$	4,102,040		$	4,062,222		$	3,951,675
GAAP revenues from real estate operations from continuing operations	$	121,893		$	117,685		$	119,364		$	119,239		$	111,074		$	358,942		$	325,671
Revenues from discontinued operations	3,236			3,121			3,077			4,474			3,954			9,434			12,344
Real estate revenues from continuing and discontinued operations	$	125,129		$	120,806		$	122,441		$	123,713		$	115,028		$	368,376		$	338,015
GAAP revenues from real estate operations from continuing operations	$	121,893		$	117,685		$	119,364		$	119,239		$	111,074		$	358,942		$	325,671
Property operating expenses	(47,655		)	(44,366		)	(49,266		)	(45,751		)	(43,013		)	(141,287		)	(128,331		)
Revenues from discontinued operations	3,236			3,121			3,077			4,474			3,954			9,434			12,344
Property operating expenses from discontinued operations	(1,057		)	(1,088		)	(1,639		)	(1,268		)	(1,291		)	(3,784		)	(4,413		)
NOI	$	76,417		$	75,352		$	71,536		$	76,694		$	70,724		$	223,305		$	205,271
Depreciation and amortization assoc. with real estate operations from continuing operations	$	35,719		$	31,059		$	30,942		$	33,558		$	29,503		$	97,720		$	84,368
Depreciation and amortization from discontinued operations	313			990			2,078			1,789			1,242			3,381			3,528
Real estate-related depreciation and amortization	$	36,032		$	32,049		$	33,020		$	35,347		$	30,745		$	101,101		$	87,896
Total tenant improvements and incentives on operating properties	$	7,082		$	11,116		$	13,270		$	8,761		$	7,789		$	31,468		$	16,490
Total capital improvements on operating properties	5,380			2,426			1,990			6,879			1,717			9,796			4,111
Total leasing costs for operating properties	4,223			3,388			2,736			4,573			2,004			10,347			4,692
Less: Nonrecurring tenant improvements and incentives on operating properties	(1,826		)	(875		)	(2,448		)	(3,003		)	(1,067		)	(5,149		)	(1,280		)
Less: Nonrecurring capital improvements on operating properties	(3,046		)	(820		)	(610		)	(1,342		)	(171		)	(4,476		)	(524		)
Less: Nonrecurring leasing costs for operating properties	(234		)	(347		)	(616		)	10			(120		)	(1,197		)	(69		)
Add: Recurring capital expenditures on operating properties held through joint ventures	20			25			22			82			4			67			27
Recurring capital expenditures	$	11,599		$	14,913		$	14,344		$	15,960		$	10,156		$	40,856		$	23,447
Interest expense from continuing operations	$	25,381		$	26,500		$	26,531		$	26,517		$	26,174		$	78,412		$	74,042
Interest expense from discontinued operations	248			330			397			361			452			975			1,208
Total interest expense	$	25,629		$	26,830		$	26,928		$	26,878		$	26,626		$	79,387		$	75,250
Less: Amortization of deferred financing costs	(1,629		)	(1,702		)	(1,759		)	(1,696		)	(1,554		)	(5,090		)	(4,175		)
Less: Amortization of net debt discounts, net of amounts capitalized	(1,184		)	(1,464		)	(1,398		)	(1,202		)	(1,496		)	(4,046		)	(3,772		)
Denominator for interest coverage	$	22,816		$	23,664		$	23,771		$	23,980		$	23,576		$	70,251		$	67,303
Scheduled principal amortization	3,226			3,623			3,798			3,607			3,420			10,647			10,389
Denominator for debt service coverage	$	26,042		$	27,287		$	27,569		$	27,587		$	26,996		$	80,898		$	77,692
Scheduled principal amortization	(3,226		)	(3,623		)	(3,798		)	(3,607		)	(3,420		)	(10,647		)	(10,389		)
Preferred dividends - redeemable non-convertible	4,025			4,026			4,025			4,026			4,025			12,076			12,076
Preferred distributions	165			165			165			165			165			495			495
Denominator for fixed charge coverage	$	27,006		$	27,855		$	27,961		$	28,171		$	27,766		$	82,822		$	79,874
Preferred dividends	$	4,025		$	4,026		$	4,025		$	4,026		$	4,025		$	12,076		$	12,076
Preferred distributions	165			165			165			165			165			495			495
Common distributions	1,781			1,808			1,809			1,816			1,834			5,398			5,450
Common dividends	29,688			29,632			27,704			27,597			24,494			87,024			70,913
Total dividends/distributions	$	35,659		$	35,631		$	33,703		$	33,604		$	30,518		$	104,993		$	88,934
Common share dividends	$	29,688		$	29,632		$	27,704		$	27,597		$	24,494		$	87,024		$	70,913
Common unit distributions	1,781			1,808			1,809			1,816			1,834			5,398			5,450
Dividends and distributions for payout ratios	$	31,469		$	31,440		$	29,513		$	29,413		$	26,328		$	92,422		$	76,363
Debt, net	$	2,420,073		$	2,299,416		$	2,396,795		$	2,323,681		$	2,468,419
Less: Construction in progress on assets held for sale	(22,936		)	(22,934		)	—			—			—
Less: Construction in progress	(447,969		)	(407,674		)	(396,170		)	(386,195		)	(344,924		)
Adjusted debt for adjusted debt to EBITDA ratio	$	1,949,168		$	1,868,808		$	2,000,625		$	1,937,486		$	2,123,495
Income (benefit) tax expense from continuing operations	$	(457	)	$	(5,042	)	$	(544	)	$	33		$	27		$	(6,043	)	$	75
Income tax expense from gain on other sales of real estate	—			—			—			—			—			—			11
Total income tax expense	$	(457	)	$	(5,042	)	$	(544	)	$	33		$	27		$	(6,043	)	$	86

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Third Quarter 2011

Definitions

Non-GAAP Measures

We believe that the measures defined below that are not determined in accordance with generally accepted accounting principles (“GAAP”) are helpful to investors in measuring our performance and comparing it to that of other real estate investment trusts (“REITs”).  Since these measures exclude certain items includable in their respective most comparable GAAP measures, reliance on the measures has limitations; management compensates for these limitations by using the measures simply as supplemental measures that are weighed in balance with other GAAP and non-GAAP measures.  These measures are not necessarily indications of our cash flow available to fund cash needs.  Additionally, they should not be used as an alternative to the respective most comparable GAAP measures when evaluating our financial performance or to cash flow from operating, investing and financing activities when evaluating our liquidity or ability to make cash distributions or pay debt service.

Funds from operations (“FFO” or “FFO per NAREIT”)

Defined as net (loss) income computed using GAAP, excluding gains on sales of previously depreciated operating properties and real estate-related depreciation and amortization.  Gains from sales of newly-developed properties less accumulated depreciation, if any, required under GAAP are included in FFO on the basis that development services are the primary revenue generating activity; we believe that inclusion of these development gains is in accordance with the National Association of Real Estate Investment Trust’s (“NAREIT”) definition of FFO, although others may interpret the definition differently and, accordingly, our presentation of FFO may differ from those of other REITs.  We believe that FFO is useful to management and investors as a supplemental measure of operating performance because, by excluding gains related to sales of previously depreciated operating properties and excluding real estate-related depreciation and amortization, FFO can help one compare our operating performance between periods.  We believe that net (loss) income is the most directly comparable GAAP measure to FFO.

Basic FFO available to common share and common unit holders (“Basic FFO”)

This measure is FFO adjusted to subtract (1) preferred share dividends, (2) income attributable to noncontrolling interests through ownership of preferred units in Corporate Office Properties, L.P. (the “Operating Partnership”) or interests in other consolidated entities not owned by us, (3) depreciation and amortization allocable to noncontrolling interests in other consolidated entities, (4) Basic FFO allocable to restricted shares and (5) issuance costs associated with redeemed preferred shares.  With these adjustments, Basic FFO represents FFO available to common shareholders and holders of common units in the Operating Partnership (“common units”).  Common units are substantially similar to our common shares of beneficial interest (“common shares”) and are exchangeable into common shares, subject to certain conditions.  We believe that Basic FFO is useful to investors due to the close correlation of common units to common shares.  We believe that net (loss) income is the most directly comparable GAAP measure to Basic FFO.

Diluted FFO available to common share and common unit holders (“Diluted FFO”)

Diluted FFO is Basic FFO adjusted to add back any changes in Basic FFO that would result from the assumed conversion of securities that are convertible or exchangeable into common shares.  The computation of Diluted FFO assumes the conversion of common units in the Operating Partnership but does not assume the conversion of other securities that are convertible into common shares if the conversion of those securities would increase Diluted FFO per share in a given period.  We believe that Diluted FFO is useful to investors because it is the numerator used to compute Diluted FFO per share, discussed below.  We believe that the numerator to diluted EPS is the most directly comparable GAAP measure to Diluted FFO.

Diluted FFO per share

Diluted FFO per share is (1) Diluted FFO divided by (2) the sum of the (a) weighted average common shares outstanding during a period, (b) weighted average common units outstanding during a period and (c) weighted average number of potential additional common shares that would have been outstanding during a period if other securities that are convertible or exchangeable into common shares were converted or exchanged.  The computation of Diluted FFO per share assumes the conversion of common units in the Operating Partnership but does not assume the conversion of other securities that are convertible into common shares if the conversion of those securities would increase Diluted FFO per share in a given period.  We believe that Diluted FFO per share is useful to investors because it provides investors with a further context for evaluating our FFO results in the same manner that investors use earnings per share (“EPS”) in evaluating net (loss) income available to common shareholders.  We believe that diluted EPS is the most directly comparable GAAP measure to Diluted FFO per share.

Diluted FFO available to common share and common unit holders, as adjusted for comparability (“Diluted FFO, as adjusted for comparability”)

Defined as Diluted FFO adjusted to exclude operating property acquisition costs, gain or loss on early extinguishment of debt, impairment losses, net of associated income tax and accounting charges for original issuance costs associated with redeemed preferred shares.  We believe that the excluded items are not reflective of normal operations and, as a result, believe that a measure that excludes these items is a useful supplemental measure in evaluating operating performance.  We believe that the numerator to diluted EPS is the most directly comparable GAAP measure to this non-GAAP measure.

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Diluted FFO per share, as adjusted for comparability

Defined as (1) Diluted FFO available to common share and common unit holders, as adjusted for comparability divided by (2) the sum of the (a) weighted average common shares outstanding during a period, (b) weighted average common units outstanding during a period and (c) weighted average number of potential additional common shares that would have been outstanding during a period if other securities that are convertible or exchangeable into common shares were converted or exchanged.  The computation of this measure assumes the conversion of common units in the Operating Partnership but does not assume the conversion of other securities that are convertible into common shares if the conversion of those securities would increase the per share measure in a given period.  As discussed above, we believe that the excluded items are not indicative of normal operations.  As such, we believe that a measure that excludes these items is a useful supplemental measure in evaluating our operating performance.  We believe that diluted EPS is the most directly comparable GAAP measure.

Diluted adjusted funds from operations available to common share and common unit holders (“Diluted AFFO”)

Defined as Diluted FFO, as adjusted for comparability, adjusted for the following: (1) the elimination of the effect of (a) noncash rental revenues and property operating expenses (comprised of straight-line rental adjustments, which includes the amortization of recurring tenant incentives, and amortization of acquisition intangibles included in FFO and NOI, both of which are described under “Cash NOI” below), (b) share-based compensation, net of amounts capitalized, (c) amortization of deferred financing costs, (d) amortization of debt discounts and premiums and (e) amortization of settlements of debt hedges; and (2) recurring capital expenditures.  Recurring capital expenditures are defined as tenant improvements and incentives, capital improvements and leasing costs for operating properties that are not (1) items contemplated prior to the acquisition of a property, (2) improvements associated with the expansion of a building or its improvements, (3) renovations to a building which change the underlying classification of the building (for example, from industrial to office or Class C office to Class B office) or (4) capital improvements that represent the addition of something new to the property rather than the replacement of something (for example, the addition of a new heating and air conditioning unit that is not replacing one that was previously there).  We believe that Diluted AFFO is an important supplemental measure of liquidity for an equity REIT because it provides management and investors with an indication of our ability to incur and service debt and to fund dividends and other cash needs.  We believe that the numerator to diluted EPS is the most directly comparable GAAP measure to Diluted AFFO.

Diluted AFFO, as adjusted for recurring capital expenditures of properties included in disposition plans

Defined as Diluted AFFO adjusted to add back recurring capital expenditures of properties included in disposition plans that were already sold or are held for future disposition.  We believe that this measure is a useful supplemental measure of liquidity because it provides management and investors with an additional indication of our ability to incur and service debt and to fund dividends and other cash needs without the effect of the recurring capital expenditures that we expect to recover through the proceeds from the property dispositions.  We believe that the numerator to diluted EPS is the most directly comparable GAAP measure to this measure.

Net operating income (“NOI”)

NOI is real estate revenues from continuing and discontinued operations reduced by total property expenses associated with real estate operations, including discontinued operations; total property expenses, as used in this definition, do not include depreciation, amortization or interest expense associated with real estate operations.  We believe that NOI is an important supplemental measure of operating performance for a REIT’s operating real estate because it provides a measure of the core real estate operations that is unaffected by depreciation, amortization, financing and general and administrative expenses; we believe this measure is particularly useful in evaluating the performance of geographic segments, same-office property groupings and individual properties.  We believe that net (loss) income is the most directly comparable GAAP measure to NOI.

Cash net operating income (“Cash NOI”)

Defined as NOI adjusted to eliminate the effects of noncash rental revenues and property operating expenses (comprised of straight-line rental adjustments, which includes the amortization of tenant incentives, and amortization of acquisition intangibles included in FFO and NOI).  Under GAAP, rental revenue is recognized evenly over the term of tenant leases.  Many leases provide for contractual rent increases and the effect of accounting under GAAP for such leases is to accelerate the recognition of lease revenue.  Since some leases provide for periods under the lease in which rental concessions are provided to tenants, the effect of accounting under GAAP is to allocate rental revenue to such periods.  Also under GAAP, when a property is acquired, we allocate the acquisition to certain intangible components (including above- and below-market leases and above or below market cost arrangements), which are then amortized into FFO and NOI over their estimated lives.  We believe that Cash NOI is an important supplemental measure of operating performance for a REIT’s operating real estate because it makes adjustments to NOI for the above stated items that are not associated with cash to us.  As is the case with NOI, the measure is useful in our opinion in evaluating and comparing the performance of geographic segments, same-office property groupings and individual properties.  We believe that net (loss) income is the most directly comparable GAAP measure to Cash NOI.

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Cash NOI, excluding gross lease termination fees

Defined as Cash NOI adjusted to eliminate the effects of lease termination fees paid by tenants to terminate their lease obligations prior to the end of the agreed lease terms.  Lease termination fees are often recognized as revenue in large one-time lump sum amounts upon the termination of tenant leases.  We believe that Cash NOI adjusted for lease termination fees is a useful supplemental measure of operating performance in evaluating same-office property groupings because it provides a means of evaluating the effect that lease terminations had on the performance of the property groupings.  We believe that net (loss) income is the most directly comparable GAAP measure to Cash NOI, excluding gross lease termination fees.

Adjusted Earnings Before Interest, Income Taxes, Depreciation and Amortization (“Adjusted EBITDA”)

Adjusted EBITDA is net (loss) income adjusted for the effects of interest expense, depreciation and amortization, impairment losses and income taxes.  We believe that adjusted EBITDA is a useful supplemental measure of performance for assessing our un-levered performance.  We believe that net (loss) income is the most directly comparable GAAP measure to adjusted EBITDA.

NOI Interest Coverage Ratio and Adjusted EBITDA Interest Coverage Ratio

These measures divide either NOI or Adjusted EBITDA by interest expense on continuing and discontinued operations (excluding amortization of deferred financing costs and amortization of debt discounts and premiums, net of amounts capitalized).

NOI Debt Service Coverage Ratio and Adjusted EBITDA Debt Service Coverage Ratio

These measures divide either NOI or Adjusted EBITDA by the sum of interest expense on continuing and discontinued operations (excluding amortization of deferred financing costs and amortization of debt discounts and premiums, net of amounts capitalized) and scheduled principal amortization on mortgage loans for continuing and discontinued operations.

NOI Fixed Charge Coverage Ratio and Adjusted EBITDA Fixed Charge Coverage Ratio

These measures divide either NOI or Adjusted EBITDA by the sum of (1) interest expense on continuing and discontinued operations (excluding amortization of deferred financing costs and amortization of debt discounts and premiums, net of amounts capitalized), (2) dividends on preferred shares and (3) distributions on preferred units in the Operating Partnership not owned by us.

Payout ratios based on: (1) Diluted FFO, as adjusted for comparability; (2) Diluted AFFO; and (3) Diluted AFFO, as adjusted for recurring capital expenditures of properties included in disposition plan

These payout ratios are defined as (1) the sum of (a) dividends on common shares and (b) distributions to holders of interests in the Operating Partnership and dividends on convertible preferred shares when such distributions and dividends are included in Diluted FFO divided by (2) the respective non-GAAP measures on which the payout ratios are based.

Dividend Coverage-Diluted FFO, as adjusted for comparability, and Dividend Coverage-Diluted AFFO

These measures divide either Diluted FFO, as adjusted for comparability, or Diluted AFFO by the sum of (1) dividends on common shares and (2) distributions to holders of interests in the Operating Partnership and dividends on convertible preferred shares when such distributions and dividends are included in Diluted FFO.

Debt to Adjusted EBITDA ratio

Defined as debt divided by Adjusted EBITDA for the three month period that is annualized by multiplying by four.

Adjusted Debt to Adjusted EBITDA ratio

Defined as (1) debt adjusted to subtract construction in progress as of the end of the period divided by (2) Adjusted EBITDA for the three month period that is annualized by multiplying by four.

Debt to Undepreciated Book Value of Real Estate Assets

Defined as the carrying value of our debt divided by total properties, net presented on our consolidated balance sheet excluding the effect of accumulated depreciation incurred to date on such properties.

Other Definitions

Acquisition costs — Transaction costs expensed in connection with executed or anticipated acquisitions of operating properties.

Annualized Rental Revenue — The monthly contractual base rent as of September 30, 2011, multiplied by 12, plus the estimated annualized expense reimbursements under existing office leases.

Greater Washington/Baltimore Region — Includes counties that comprise the Baltimore/Washington Corridor, Northern Virginia,

Greater Baltimore, Suburban Maryland, St. Mary’s & King George Counties, and the Washington, DC-Capitol Riverfront.

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Same Office Properties — Operating office properties owned and 100% operational since January 1, 2010, excluding properties held for future disposition.

Strategic Reallocation Plan — Plan approved by our Board of Trustees on April 25, 2011 to dispose of properties that are no longer closely aligned with our strategy during the next three years.

Strategic Tenant Properties — Properties occupied primarily by tenants in the United States Government and defense information technology sectors and data centers serving such sectors.

Under Construction — Properties on which vertical construction activities are underway.

Under Pre-Construction — Properties on which work associated with one or more of the following tasks is underway on a regular basis: pursuing entitlements, planning, design and engineering, bidding, permitting and premarketing/preleasing. Typically, these projects, as categorized in this Supplemental Information package, are targeted to begin construction in 12 months or less.

Under Redevelopment — Properties previously in operations on which activities to substantially renovate such properties are underway.

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