QuickLinks -- Click here to rapidly navigate through this document


SLM Corporation

Medium Term Notes, Series B

LOGO

With Maturities of 9 Months or More from Date of Issue

Registration No. 333-90316
Filed Pursuant to Rule 424(b)(3)

Pricing Supplement    No. 128   Trade Date:   8/18/03
(To Prospectus dated January 23, 2003 and   Issue Date:   8/21/03
Prospectus Supplement dated January 23, 2003)        

The date of this Pricing Supplement is                8/18/03

 
   
   
   
   
  Interest Payment
   
  Subject to Redemption
   
   
   
CUSIP

  Stated Interest Rate Per Annum(1)
  Maturity
Date

  Price to
Public(2)(3)

  Discounts &
Commissions

  Frequency
  First
Payment

  Survivor's
Option

  Yes/No
  Date and terms of redemption
  Aggregate
Principal
Amount

  Net
Proceeds

  OID
Status

78490FFH7   *Step   12/15/18   100 % 2.000 % Semi   12/15/03   Yes   Yes   Callable at 100% on 6/15/2006 and continuously thereafter with 20 days notice.   1,015,000   994,700.00   N
*
5.00% until but not including 6/15/08, and 6.25% thereafter payable beginning on 12/15/08


Effective April 7, 2003 the name of Salomon Smith Barney Inc., an agent of the program, was changed to Citigroup Global Markets Inc.

(1)
The interest rates on the Ed Notes may be changed by SLM Corporation from time to time, but any such change will not affect the interest rate on any Ed Notes offered prior to the effective date of the change.

(2)
Expressed as a percentage of aggregate principal amount.

(3)
See "Supplemental Plan of Distribution" in the Prospectus supplement for additional information concerning price to public and underwriting compensation.



QuickLinks

SLM Corporation Medium Term Notes, Series B