Exhibit 99.1

SECOND QUARTER 2004

Supplemental Operating and Financial Data

        This Supplemental Operating and Financial Data is not an offer to sell or solicitation to buy any securities of the Company. Any offers to sell or solicitations of the Company shall be made by means of a prospectus. The information in this Supplemental Package must be read in conjunction with, and is modified in its entirety by, the Quarterly Report on Form 10-Q (the "10-Q") filed by the Company for the same period with the Securities and Exchange Commission (the "SEC") and all of the Company's other public filings with the SEC (the "Public Filings"). In particular, the financial information contained herein is subject to and qualified by reference to the financial statements contained in the 10-Q, the footnotes thereto and the limitations set forth therein. Investors may not rely on the Supplemental Package without reference to the 10-Q and the Public Filings. Any investors' receipt of, or access to, the information contained herein is subject to this qualification.

INDEX

2

DISCLOSURE REGARDING FORWARD-LOOKING STATEMENTS

        The Company considers portions of the information presented herein to be forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and the federal securities laws, including Section 21E of the Securities Exchange Act of 1934. The Company intends such forward-looking statements to be covered by the safe harbor provisions for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995 and Section 21E of the Securities Exchange Act of 1934. Such forward-looking statements relate to, without limitation, the Company's future economic performance, plans and objectives for future operations and projections of revenue and other financial items. Forward-looking statements can be identified by the use of words such as "may," "will," "should," "expect," "anticipate," "estimate," "continue," or comparable terminology. Although the Company believes that the expectations reflected in such forward-looking statements are based upon reasonable assumptions at the time made, it can give no assurance that its expectations will be achieved. Forward-looking statements are inherently subject to certain risks, trends and uncertainties, many of which the Company cannot predict with accuracy and some of which the Company might not even anticipate. Future events and actual results, financial and otherwise, may differ materially from the results discussed in the forward-looking statements. Readers are cautioned not to place undue reliance on these forward-looking statements. Among the risks, trends and uncertainties are changes in the general economic conditions, including those affecting industries in which the Company's principal tenants compete; any failure of the general economy to recover timely from the current economic downturn; the extent of any tenant bankruptcies; the Company's ability to lease or re-lease space at current or anticipated rents; changes in the supply of and demand for office, office/flex and industrial/warehouse properties; changes in interest rate levels; changes in operating costs; the Company's ability to obtain adequate insurance, including coverage for terrorist acts; the availability of financing; and other risks associated with the development and acquisition of properties, including risks that the development may not be completed on schedule, that the tenants will not take occupancy or pay rent, or that development or operating costs may be greater than anticipated. For further information on factors which could impact the Company and the statements contained herein, reference should be made to the Company's filings with the Securities and Exchange Commission including Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and Annual Reports on Form 10-K. The Company assumes no obligation to update or supplement forward-looking statements that become untrue because of subsequent events, new information or otherwise.

3

I.    COMPANY BACKGROUND

4

I.    COMPANY BACKGROUND

About the Company

        Mack-Cali Realty Corporation (NYSE: CLI) is one of the largest real estate investment trusts (REITs) in the United States with a total market capitalization of $4.8 billion at June 30, 2004. Mack-Cali has been involved in all aspects of commercial real estate development, management and ownership for over 50 years and has been a publicly-traded REIT since 1994. Mack-Cali owns or has interests in 270 properties, primarily class A office and office/flex buildings, totaling approximately 30 million square feet, serving as home to approximately 2,100 tenants. The properties are located primarily in suburban markets of the Northeast, many with adjacent, Company-controlled developable land sites able to accommodate up to 9 million square feet of additional commercial space.

History

        Established over 50 years ago, in 1994 the New Jersey-based firm became a publicly-traded company listed on the New York Stock Exchange under the ticker symbol CLI. Through combinations with some of the top companies in the real estate industry—most notably New Jersey-based Mack Company and Westchester, New York-based Robert Martin Company—Mack-Cali has become one of the leading real estate companies in the country.

Strategy

        Mack-Cali's strategy is to be a significant real estate owner and operator in its core, high-barriers-to-entry markets, primarily in the Northeast.

Summary
(as of June 30, 2004)

5

Board of Directors

William L. Mack, Chairman of the Board

Executive Officers

        Mitchell E. Hersh, President and Chief Executive Officer

        Barry Lefkowitz, Executive Vice President and Chief Financial Officer

        Roger W. Thomas, Executive Vice President, General Counsel and Secretary

        Michael A. Grossman, Executive Vice President

6

Equity Research Coverage

Company Contact Information

Mack-Cali Realty Corporation
Investor Relations Department
11 Commerce Drive
Cranford, New Jersey 07016-3599

7

II.    FINANCIAL HIGHLIGHTS

8

II. FINANCIAL HIGHLIGHTS

Quarterly Summary

        Net income available to common shareholders for the second quarter 2004 equaled $15.8 million, or $0.26 per share, versus $33.6 million, or $0.58 per share, for the same quarter last year. For the six months ended June 30, 2004, net income available to common shareholders equaled $42.1 million, or $0.69 per share, versus $63.6 million, or $1.10 per share, for the same period last year.

        Funds from operations (FFO) available to common shareholders for the quarter ended June 30, 2004 amounted to $67.6 million, or $0.90 per share, versus $70.7 million, or $0.98 per share, for the quarter ended June 30, 2003. For the six months ended June 30, 2004, FFO available to common shareholders amounted to $132.5 million, or $1.77 per share, versus $139.7 million, or $1.95 per share, for the same period last year.

        Total revenues for the second quarter 2004 increased 3.0 percent to $146.7 million as compared to $142.4 million for the same quarter last year. For the six months ended June 30, 2004, total revenues amounted to $290.7 million, an increase of 1.4 percent over total revenues of $286.8 million for the same period last year.

        All per share amounts presented above are on a diluted basis.

        The Company had 60,606,543 shares of common stock, 10,000 shares of cumulative redeemable perpetual preferred stock, 7,788,748 common operating partnership units and 215,018 $1,000-face-value preferred operating partnership units outstanding as of June 30, 2004.

        The outstanding preferred units are convertible into 6,205,425 common operating partnership units. Assuming conversion of all preferred units into common units, the Company had a total of 74,600,716 shares/common units outstanding at June 30, 2004.

        As of June 30, 2004, the Company had total indebtedness of approximately $1.7 billion, with a weighted average annual interest rate of 6.41 percent. Mack-Cali had a total market capitalization of $4.8 billion and a debt-to-undepreciated assets ratio of 38.4 percent at June 30, 2004. The Company had an interest coverage ratio of 3.5 times for the quarter ended June 30, 2004.

        The following is a summary of the Company's recent activity:

Acquisitions

        On June 1, in a strategic real estate transaction with AT&T Corporation ("AT&T"), the Company:

1.

Acquired 30 Knightsbridge Road, a four-building office complex, aggregating 680,350 square feet and located in Piscataway, New Jersey. AT&T, which currently occupies the entire complex, has leased back from the Company two of the buildings in the complex, totaling 275,000 square feet, for 10 years and seven months, and has leased back the remaining 405,350 square feet of the complex pursuant to a four-month lease with rights for AT&T to extend;



2.

Acquired Kemble Plaza II, a 475,100 square-foot office building located in Morris Township, New Jersey, which the Company had previously sold to AT&T in June of 2000. AT&T, which currently occupies the entire building, has leased back the entire property from the Company for one year;



3.

Signed a lease extension at the Company's Kemble Plaza I property in Morris Township, New Jersey, extending AT&T's lease for the entire 387,000 square-foot building for an additional five years to August 2014. Under the lease extension, the Company has agreed, among other

9

things, to fund up to $2.1 million of tenant improvements to be performed by AT&T at the property;

4.

Paid cash consideration of approximately $12.9 million to AT&T; and



5.

Assumed AT&T's lease obligations with third-party landlords at seven office buildings, aggregating 922,674 square feet, which carry a weighted average remaining term of 4.5 years. The Company has estimated that the obligations, net of estimated sub-lease income, total approximately $84.8 million, with a net present value of approximately $76.2 million utilizing a weighted average discount rate of 4.85 percent. The net present value of the assumed obligations as of June 30, 2004 is included in mortgages, loans payable and other obligations.

        Also in June, the Company acquired a 59.9 acre land site in the Princeton, New Jersey, submarket for $20.5 million. Located at Route One and Meadow Road in West Windsor, adjacent to the Carnegie Center office complex, the site is approved for the development of approximately 760,000 square feet of commercial space, including four office buildings totaling 607,000 square feet and a hotel.

        In April, the Company acquired 5 Wood Hollow Road, a three-story, 317,040 square-foot class A office property located in Parsippany, New Jersey. The building was purchased for approximately $34 million. The acquisition of 5 Wood Hollow Road, which is 100 percent leased to Lucent Technologies, increased the Company's holdings in Parsippany to 14 buildings totaling 2.2 million square feet.

Financing Activity

        In June, the Company's Board of Directors declared a cash dividend of $0.63 per common share (indicating an annual rate of $2.52 per common share) for the second quarter 2004, which was paid on July 19, 2004 to shareholders of record as of July 6, 2004. The Board also declared a cash dividend on its 8 percent Series C cumulative redeemable perpetual preferred stock ($25 liquidation value per depositary share, each representing 1/100^th of a share of preferred stock) equal to $0.50 per depositary share for the period April 15, 2004 through July 14, 2004. The dividend was paid on July 15, 2004 to shareholders of record as of July 6, 2004.

Leasing Information

        Mack-Cali's consolidated in-service portfolio was 92.2 percent leased at June 30, 2004, compared to 91.1 percent leased at March 31, 2004 and 91.5 percent leased at December 31, 2003.

        For the quarter ended June 30, 2004, the Company executed 188 leases totaling 1,523,709 square feet, consisting of 1,299,588 square feet of office space, 217,483 square feet of office/flex space and 6,638 square feet of industrial/warehouse space. Of these totals, 470,978 square feet were for new leases and 1,052,731 square feet were for lease renewals and other tenant retention transactions.

        In addition to AT&T's 387,000 square-foot extension at Kemble Plaza I, highlights of the quarter's leasing transactions include:

•

United Retail Incorporated, a specialty retailer of women's apparel, signed a 10-year renewal of its lease for 65,271 square feet at 365 West Passaic Street in Rochelle Park, New Jersey. The 212,578 square-foot class A office building is 93.2 percent leased.



•

Jefferies & Company, Inc., an investment bank and operating subsidiary of Jefferies Group, Inc., leased 48,060 square feet, renewing its lease for 42,142 square feet for five years, and expanding its space by 5,918 square feet at Harborside Financial Center Plaza 3 in Jersey City, New Jersey. The 725,600 square-foot class A office building is 100 percent leased.

10

•

State Farm Mutual Auto Insurance signed a new, six-year lease for 47,633 square feet at 9777 Mt. Pyramid Court in Englewood, Colorado. The 120,281 square-foot office building is 91.3 percent leased. In a separate transaction, State Farm extended the term of its lease by 18 months for 12,333 square feet at 1433 Highway 34 in Wall Township, New Jersey.



•

Coca-Cola Enterprises, Inc. renewed 44,266 square feet for 10 years, relocating from the Company's property at 3 Skyline Drive in Hawthorne, New York to its 555 Taxter Road building in Elmsford, New York. 555 Taxter Road, located at Taxter Corporate Park, is a 170,554 square-foot class A office building and is 91.7 percent leased.



•

The Sherwin Williams Company, a manufacturer, distributor and seller of coatings and related products, renewed its lease for 37,055 square feet at 10 Mountainview Road in Upper Saddle River, New Jersey. The 192,000 square-foot class A office building is 99.1 percent leased.



•

Fiberlink Communications Corp., a provider of remote access and security solutions, signed a new 10-year lease for 36,360 square feet at 18 Sentry Park West in Blue Bell, Pennsylvania. The 95,010 square-foot class A office property, located at the Sentry Park Office Campus, is 95.4 percent leased.



•

Long Beach Acceptance Corp., a provider of automotive financing, signed a five-year renewal for its 34,759 square-foot headquarters at 650 From Road in Paramus, New Jersey for five years. The 348,510 square-foot class A office building is 97 percent leased.

Information About FFO

        Funds from operations ("FFO") is defined as net income (loss) before minority interest of unitholders, computed in accordance with generally accepted accounting principles ("GAAP"), excluding gains (or losses) from extraordinary items and sales of depreciable rental property (which the Company believes includes unrealized losses on properties held for sale), plus real estate-related depreciation and amortization. The Company believes that FFO per share is helpful to investors as one of several measures of the performance of an equity REIT. The Company further believes that by excluding the effect of depreciation and gains (or losses) from sales of properties (all of which are based on historical costs which may be of limited relevance in evaluating current performance), FFO per share can facilitate comparison of operating performance between equity REITs. FFO per share should not be considered as an alternative to net income per share as an indication of the Company's performance or to cash flows as a measure of liquidity. FFO per share presented herein is not necessarily comparable to FFO per share presented by other real estate companies due to the fact that not all real estate companies use the same definition. However, the Company's FFO per share is comparable to the FFO per share of real estate companies that use the current definition of the National Association of Real Estate Investment Trusts ("NAREIT"). A reconciliation of net income per share to FFO per share is included in the financial tables on page 28.

11

Key Financial Data

(a)

Includes preferred units on a converted basis into common units.

(b)

Calculated based on weighted average common shares outstanding, assuming redemption of operating partnership common units into common shares.

(c)

Calculated based on shares and units included in basic per share/unit computation, plus dilutive Common Stock Equivalents (i.e. convertible preferred units, options and warrants).

12

(d)

Includes preferred units on a converted basis into common units and minority interests in partially-owned properties.

(e)

Funds from Operations ("FFO") is calculated in accordance with the definition of the National Association of Real Estate Investment Trusts (NAREIT). See "Information About FFO" on page 11.

(f)

Reflects square feet leased at the Company's consolidated in-service portfolio, excluding in-service development properties in lease up (if any). Excluded from percentage leased at June 30, 2004 is a non-strategic, non-core 318,224 square-foot property acquired through a deed in lieu of foreclosure, which was 71.1 percent leased at June 30, 2004.

13

Same Store Results and Analysis(a)
(dollars in thousands)

(a)

Excludes three properties identified as held for sale at June 30, 2004.

14

Unconsolidated Joint Ventures Summary

Breakdown of Unconsolidated Joint Ventures

(a)

Property consists of a three-story theater and retail complex.

(b)

The venture is developing a family entertainment and recreation complex with an office and hotel component to be built at the Meadowlands sports complex in East Rutherford, New Jersey ("Meadowlands Xanadu"). Meadowlands Xanadu's approximately 4.76 million-square-foot complex is expected to feature a family entertainment destination comprising three themed zones: sports/recreation, children's activities and fashion, in addition to four office buildings, aggregating approximately 1.8 million square feet, and a 520-room hotel.

15

Unconsolidated Joint Venture Financial Information

        The following is a summary of the financial position of the unconsolidated joint ventures in which the Company had investment interests as of June 30, 2004 and December 31, 2003:

16

        The following is a summary of the results of operations of the unconsolidated joint ventures for the period in which the Company had investment interests during the three months ended June 30, 2004 and 2003:

17

        The following is a summary of the results of operations of the unconsolidated joint ventures for the period in which the Company had investment interests during the six months ended June 30, 2004 and 2003:

18

Select Financial Ratios