COPT DEFENSE PROPERTIES

This summary highlights selected information about COPT Defense Properties (“COPT Defense” or the “Company”) contained in this proxy statement, but it does not contain all the information you should consider in making your vote. We urge you to read the whole proxy statement before you vote. This proxy statement is being made available to shareholders on or about March 30, 2026.

SHAREHOLDERS WILL BE VOTING ON THE FOLLOWING MATTERS

TRUSTEE NOMINEES

2025 BUSINESS HIGHLIGHTS

Our 2025 business highlights included:

•strong occupancy and leased rates, vacancy leasing and tenant retention driven by strong demand for space across our Defense/IT Portfolio sub-segments and unique advantages associated with our Defense/IT strategy;

•continued growth through development, with three fully-leased properties placed in service and new capital commitments to develop four properties, three of which were fully pre-leased;

•strategic acquisition of a fully-leased operating property in one of our existing supply-constrained Defense/IT Portfolio submarkets;

•successful closing on three new financings, which pre-funded the repayment at maturity of a bond in March 2026 and provided additional liquidity to fund our external growth;

•growth in results of operations due primarily to increased rental and occupancy rates in our Same Property portfolio and from external growth in our portfolio, including newly-developed properties placed in service and property acquisitions; and

•strong liquidity and financial position at year end, with the ability to fund the equity portion of our investing activities with cash flow from operations for the foreseeable future.

These highlights positioned the Company to exceed all but one of the objectives established in its 2025 corporate scorecard used under our executive compensation program, as described below under “Compensation Discussion and Analysis.”

ANNUAL SHAREHOLDER SAY-ON-PAY VOTES

COMPENSATION HIGHLIGHTS

We design our compensation programs to link executive compensation to annual financial results and long-term total shareholder return (“TSR”). Our executive compensation program is designed to:

•align pay to performance;

•be commensurate to the compensation levels of executives performing similar responsibilities for an appropriate group of peer companies; and

•provide an appropriate balance between the various components of our executives’ compensation.

Our executive compensation includes:

•base salary as the fixed component intended to attract and retain executives;

•annual incentive award (“AIA”) cash bonuses that are formulaic and based on achievement of objectives established at the beginning of each year, approved by the Compensation Committee, and set forth in our annual corporate scorecard; and

•annual long-term equity incentive plan (“LTIP”) awards.

The compensation of our NEOs is predominantly performance-based, including AIAs and LTIP awards that are subject to objective performance thresholds, as reflected in the graphic below:

SHAREHOLDER OUTREACH

We place a high value on our Investor Relations function, as we routinely engage with existing and prospective shareholders and sell-side analysts in a variety of forums throughout the year.

In 2025, we held approximately 90 meetings, either in person or virtually, amounting to approximately 245 touchpoints with investors and sell-side analysts. We participated in seven real estate conferences throughout 2025, sponsored by Nareit, Citi, Wells Fargo, Evercore ISI, BofA Securities, and Jefferies. In addition, to deepen our investors’ understanding of the Company and our assets, we hosted 12 property tours, amounting to approximately 45 additional touchpoints with investors and sell-side analysts. These tours were an effective means of communicating to investors and analysts how our strategy provides a distinct competitive advantage, which includes our unique and advantaged land positions, expertise in developing and operating secured, specialized space, credentialed workforce and long-standing customer relationships.

We believe that our engagement efforts have been well received, as we were one of six companies nominated by IR Magazine for best in sector for real estate in 2025.

Frequently discussed topics through our shareholder outreach include:

•outlook for the 2026 fiscal year’s U.S. Department of Defense budget and implications for tenant demand;

•leasing environment;

•market fundamentals such as supply, demand, and price;

•progress towards vacancy and investment leasing goals;

•external growth opportunities from development and acquisitions;

•sources and uses of capital;

•capital markets risk and exposure;

•financial position; and

•earnings and dividends growth outlook.

SUSTAINABILITY

As further detailed in the section below entitled “Company’s Commitment to Sustainability,” we remain committed to maintaining and enhancing our sustainable development and building operations programs, thereby creating a more resilient and efficient portfolio that benefits our tenants and our shareholders. Our governance structure positions the Board to provide oversight with respect to the Company’s environmental risks and opportunities.

Recent Achievements

Received Green Star recognition from GRESB for the 11th consecutive year.

Reported information with respect to the Company’s risks and emissions data to align with applicable frameworks under both Task Force on Climate-related Financial Disclosures, Sustainability Accounting Standards Board, and Global Reporting Initiative.

Recognized by Newsweek as one of America’s Most Responsible Companies in 2025, based on 2024 data, in the Real Estate and Housing Industry.

Accelerated the completion of our Corporate Sustainability Report to facilitate publishing in advance of the Annual Shareholder meeting, improving insight into how we address sustainability issues.