Exhibit 99.1

FOURTH QUARTER 2003

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 Annual Report on Form 10-K (the "10-K") 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-K, the footnotes thereto and the limitations set forth therein. Investors may not rely on the Supplemental Package without reference to the 10-K and the Public Filings. Any investors' receipt of, or access to, the information contained herein is subject to this qualification.

INDEX

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DISCLOSURE REGARDING FORWARD-LOOKING STATEMENTS

Certain information discussed in this literature may constitute 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.

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I.    COMPANY BACKGROUND

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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 $4.7 billion at December 31, 2003. 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 263 properties, primarily class A office and office/flex buildings, totaling approximately 28.3 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 8.3 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 December 31, 2003)

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Board of Directors

William L. Mack, Chairman of the Board

Executive Officers

Mitchell E. Hersh, Chief Executive Officer

Timothy M. Jones, President

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

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Equity Research Coverage

Company Contact Information

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

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II.    FINANCIAL HIGHLIGHTS

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II.    FINANCIAL HIGHLIGHTS

Quarterly/Annual Summary

        Funds from operations (FFO) available to common shareholders for the quarter ended December 31, 2003 amounted to $66.5 million, or $0.91 per share, versus $68.3 million, or $0.96 per share, for the quarter ended December 31, 2002. For the year ended December 31, 2003, FFO available to common shareholders amounted to $275.7 million, or $3.82 per share, versus $281.8 million, or $3.93 per share, for 2002.

        Net income available to common shareholders for the fourth quarter 2003 equaled $27.4 million, or $0.47 per share, versus $29.8 million, or $0.52 per share, for the same quarter last year, a per share decrease of 9.6 percent. For the year ended December 31, 2003, net income available to common shareholders equaled $141.4 million, or $2.43 per share, versus $139.7 million, or $2.43 per share, for last year.

        Total revenues for the fourth quarter 2003 increased 5.5 percent to $147.6 million as compared to $139.9 million for the same quarter last year. For the year ended December 31, 2003, total revenues amounted to $586.2 million, an increase of 4.0 percent over total revenues of $563.6 million in 2002.

        All per share amounts presented above are on a diluted basis; basic earnings per share is included in the financial tables on page 23.

        The Company had 59,420,484 shares of common stock, 10,000 shares of cumulative redeemable perpetual preferred stock, 7,795,498 common operating partnership units and 215,018 $1,000-face-value preferred operating partnership units outstanding as of year end.

        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 73,421,407 shares/common units outstanding at December 31, 2003.

        As of December 31, 2003, the Company had total indebtedness of approximately $1.6 billion, with a weighted average annual interest rate of 7.10 percent. Mack-Cali had a total market capitalization of $4.7 billion and a debt-to-undepreciated assets ratio of 37.9 percent at December 31, 2003. The Company had an interest coverage ratio of 3.28 times for the quarter ended December 31, 2003.

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

Sales Activity

        In October, the Company sold Riverview Tower, a 248,153 square-foot office building located in San Antonio, Texas, for approximately $11 million.

        In November, the Company sold 27.7 acres of land in Hamilton Township, New Jersey, for approximately $2.5 million.

Financing Activity

        In December, 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 fourth quarter 2003, which was paid on January 16, 2004 to shareholders of record as of January 6, 2004. The Board of Directors also declared a cash dividend of $0.50 per depositary share, each representing 1/100^th of a share of 8 percent Series C cumulative redeemable perpetual preferred stock ($25 liquidation value per depositary share) for the period October 15, 2003 through January 14, 2004. The preferred stock dividend was paid on January 15, 2004 to shareholders of record as of January 6, 2004.

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        More recently, in January 2004 the Company through its operating partnership, sold $100 million of 10-year senior unsecured notes. The 5.125 percent notes are due February 15, 2014. The proceeds from the issuance of approximately $98.5 million will be applied to the repayment of 7-percent, $300 million face amount unsecured notes at maturity on March 15, 2004.

Leasing Information

        Mack-Cali's consolidated in-service portfolio was 91.5 percent leased at December 31, 2003, compared to 90.7 percent leased at September 30, 2003, and 92.3 percent leased at December 31, 2002.

        For the quarter ended December 31, 2003, the Company executed 173 leases totaling 940,716 square feet. For the year ended December 31, 2003, the Company executed 679 leases totaling 4,162,005 square feet.

        Leases for the quarter ended December 31, 2003 consisted of: 677,413 square feet of office space; 241,203 square feet of office/flex space; and 22,100 square feet of industrial/warehouse space. Of these totals, 382,265 square feet were for new leases and 558,451 square feet were for lease renewals and other tenant retention transactions.

        Highlights of the quarter's leasing transactions include:

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Prudential Insurance Company signed a seven-year, 75,174 square foot lease transaction at 8 Campus Drive in Parsippany, New Jersey. The transaction represents a renewal of 66,956 square feet and expansion of 8,578 square feet. 8 Campus Drive, a 215,265 square-foot class A office property located in the Mack-Cali Business Campus, is 100 percent leased.



•

Jack and Jill Ice Cream Co., a distributor of ice cream and other frozen confections, signed a new 15-year lease for 64,700 square feet, representing the entire office/flex building located at 101 Commerce Drive in Moorestown, New Jersey. The building is located in the Moorestown West Corporate Center.



•

Fremont Investment & Loan, a financial services company, signed a 30,000 square foot expansion for 10 years at 555 Taxter Road in Elmsford, New York. The 170,554 square-foot class A office building is 63.6 percent leased.



•

Montefiore Medical Center, one of the largest health care systems in the nation, signed an expansion of 26,475 square feet for 15 years, and now leases 100 percent of the 71,065 square-foot office building at Three Odell Plaza at the South Westchester Executive Park in Yonkers, New York.



•

Unitrin Direct Insurance Company, a subsidiary of financial services provider Unitrin, Inc., signed a new lease for 21,814 square feet for seven years at One Plymouth Meeting in Plymouth Meeting, Pennsylvania. The 167,748 square-foot office building is 94.7 percent leased.



•

Prints Plus, Inc., a provider of printing and copying services, renewed its lease for 20,717 square feet at 250 Clearbrook Road in the Cross Westchester Executive Park in Elmsford, New York for five years. The 155,000 square-foot office/flex building is 94.5 percent leased.



•

Office of Thrift Supervision, the primary regulator of all federally chartered thrift institutions, signed a new, 16-year lease for 20,664 square feet at Harborside Plaza 5 in Jersey City, New Jersey. The 977,225 square-foot, class A office building is 60.1 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

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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 27.

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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).

(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 10.

(f)

Reflects square feet leased at the Company's consolidated in-service portfolio, excluding in-service development properties in lease up (if any).

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Same Store Results and Analysis
(dollars in thousands)

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Unconsolidated Joint Ventures Summary

Breakdown of Unconsolidated Joint Ventures

(a)

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

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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 December 31, 2003 and 2002:

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        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 years ended December 31, 2003 and 2002:

(a)

Represents results of operations for period in which Company had ownership interest of January 1, 2003 through September 28, 2003.

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        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 December 31, 2003 and 2002: