- -------- U.S. SECURITIES AND EXCHANGE COMMISSION FORM 4 Washington, D.C. 20549 - -------- / / CHECK THIS BOX IF NO STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP LONGER SUBJECT TO SECTION 16. FORM 4 OR Filed pursuant to Section 16(a) of the Securities and Exchange Act of 1934, FORM 5 OBLIGATIONS MAY Section 17(a) of the Public Utility Holding Company Act of 1935 or CONTINUE. Section 30(f) of the Investment Company Act of 1940 SEE INSTRUCTION 1(b). - ------------------------------------------------------------------------------------------------------------------------------------ 1. Name and Address of Reporting Person* 2. Issuer Name and Ticker or Trading Symbol 6. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X_ Director ____ 10% Owner Byrne Brendan T. Mack-Cali Realty Corporation (CLI) - --------------------------------------------------------------------------------------------- ____ Officer (give ____ Other (Last) (First) (Middle) 3. IRS or Social Security 4. Statement for title (specify Number of Reporting Month/Year below) below Person (Voluntary) ----------------- ------------------ c/o Mack-Cali Realty Corporation 11 Commerce Drive 12/99 - -------------------------------------------- --------------------- 7. Individual or Joint/Group Filing (Street) 5. If Amendment, (Check Applicable Line) Date of Original _X_Form filed by One Reporting Person Cranford, New Jersey 07016 (Month/Year) ___Form filed by More than One - -------------------------------------------- Reporting Person (City) (State) (Zip) - ------------------------------------------------------------------------------------------------------------------------------------ TABLE I - NON-DERIVATIVE SECURITIES ACQUIRED, DISPOSED OF, OR BENEFICIALLY OWNED - ------------------------------------------------------------------------------------------------------------------------------------ 1. Title of Security 2. Trans- 3. Trans- 4. Securities Acquired (A) 5. Amount of 6. Owner- 7. Nature (Instr. 3) action action or Disposed of (D) Securities ship of In- Date Code (Instr. 3, 4 and 5) Beneficially Form: direct (Month/ (Instr. 8) Owned at Direct Bene- Day/ End of (D) or ficial Year) ------------------------------------------- Month Indirect Owner- Code V Amount (A) or (Instr. 3 (I) ship (D) Price and 4) (Instr. 4) (Instr. 4) - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 12/13/99 P 500 A $24.187 600 I By wife - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ * If the form is filed by more than one reporting person, SEE Instruction 4(b)(v). Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. (Over)

FORM 4 (CONTINUED) TABLE II - DERIVATIVE SECURITIES ACQUIRED, DISPOSED OF, OR BENEFICIALLY OWNED (E.G., PUTS, CALLS, WARRANTS, OPTIONS, CONVERTIBLE SECURITIES) - ------------------------------------------------------------------------------------------------------------------------ 1. Title of Derivative Security 2. Conver- 3. Trans- 4. Transac- 5. Number of Deriv- 6. Date Exer- (Instr. 3) sion or action tion Code ative Securities Ac- cisable and Ex- Exercise Date (Instr. 8) quired (A) or Dis- piration Date Price of (Month/ posed of (D) (Month/Day/ Deriv- Day/ (Instr. 3, 4, and 5) Year) ative Year) Security ---------------------------------------------------------- Code V (A) (D) Date Expira- Exer- tion cisable Date - ------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------

- ------------------------------------------------------------------------------------------ 7. Title and Amount of Under- 8. Price 9. Number 10. Owner- 11. Nature lying Securities of of Deriv- ship of In- (Instr. 3 and 4) Deriv- ative Form direct ative Securi- of De- Bene- Secur- ties rivative ficial ity Bene- Secu- Own- (Instr. ficially rity: ership 5) Owned Direct (Instr. 4) - ------------------------------- at End (D) or Title Amount or of Indi- Number of Month rect (I) Shares (Instr. 4) (Instr. 4) - ------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------ Explanation of Responses: /s/ Brendan T. Byrne 1/10/00 ----------------------------------- ----------- **Intentional misstatements or omissions of facts constitute **Signature of Reporting Person Date Federal Criminal Violations. SEE 18 U.S.C. 1001 and 15 U.S.C. 78ff(a). Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, SEE Instruction 6 for procedure. Page 2