Prospectus Supplement No. 2127                        File No. 333-52822
- ------------------------------                        Rule 424(b)(3)
To (A) the Medium - Term Notes                        Market Making Transactions
(no series designated)
Prospectus dated January 24, 2001,
and (B) the Medium - Term Notes (Series B)
Prospectus and Prospectus Supplement
dated January 24, 2001.




                            Merrill Lynch & Co., Inc.
                   Medium - Term Notes (no series designated)
                         Medium - Term Notes (Series B)


     This Prospectus is used by Merrill Lynch, Pierce, Fenner & Smith
Incorporated ("MLPF&S"), a wholly owned subsidiary of Merrill Lynch & Co., Inc.
("ML&Co."), in connection with offers and sales related to market-making
transactions in the Medium-Term Notes (no series designated) and Medium-Term
Notes (Series B) of ML & Co. in which transactions MLPF&S acts as a principal.
Such sales will be made at prices related to prevailing market prices at the
time of sale.

     As of March 30, 2001, Medium-Term Notes (no series designated) and
Medium-Term Notes (Series B) of ML & Co. have been issued and are currently
outstanding as follows:

     From 9 Months but less than 12 Months                     N/A
     From 12 Months but less than 18 Months              4.635% to 7.55%
     From 18 Months but less than 2 Years                 7.02% to 7.62%
     From 2 Years but less than 3 Years                   5.31% to 7.65%
     From 3 Years but less than 4 Years                    5.7% to 7.85%
     From 4 Years but less than 5 Years                   5.64% to 7.15%
     From 5 Years but less than 6 Years                   2.00% to 7.25%
     From 6 Years but less than 7 Years                        6.18%
     From 7 Years but less than 10 Years                   .25% to 7.3%
     10 Years or more                                    5.526% to 8.125%


MLPF&S may also act as an agent for its customers in connection with other
secondary market transactions in the Medium-Term Notes (no series designated)
and Medium-Term Notes (Series B).


          o   This reflects actual interest rates for fixed rate Medium-Term
              Notes (no series designated) and Medium-Term Notes (Series B). ML
              & Co. also has outstanding a variety of floating rate Medium-Term
              Notes (no series designated) and Medium-Term Notes (Series B), the
              interest rates of which are reset periodically depending on
              various indices. In addition, ML & Co. has outstanding Medium-Term
              Notes (Series B) the return on which is correlated to changes in
              the market price of various equity securities or the level of
              various published indices, or baskets thereof, as the case may be.


Dated:  May 22, 2001