PROSPECTUS SUPPLEMENT File No. 333-68747 (To Prospectus and Prospectus Supplement dated May 6, 1999) Rule 424(b)(3) Prospectus number: 1958 Merrill Lynch & Co., Inc. Medium-Term Notes, Series B Due Nine Months or More from Date of Issue Floating Rate Notes Principal Amount: $200,000,000 Original Issue Date: April 28, 2000 CUSIP Number: 59018S 6J8 Stated Maturity Date: April 30, 2001 Interest Calculation: Day Count Convention: - --------------------- --------------------- |x| Regular Floating Rate Note |x| Actual/360 | | Inverse Floating Rate Note | | 30/360 (Fixed Interest Rate): | | Actual/Actual Interest Rate Basis: - -------------------- | | LIBOR | | Commercial Paper Rate | | CMT Rate | | Eleventh District Cost of Funds Rate | | Prime Rate | | CD Rate |x| Federal Funds Rate | | Other (see attached) | | Treasury Rate Designated CMT Page: Designated LIBOR Page: CMT Telerate Page: LIBOR Telerate Page: 3750 CMT Reuters Page: LIBOR Reuters Page: