Nuveen S&P 500 Dynamic Overwrite Fund (SPXX) 424B3 Prospectus supplement

Filed Pursuant to Rule 424(b)(3)

File No. 333-237421

NUVEEN S&P 500 DYNAMIC OVERWRITE FUND

(NYSE: SPXX)

(THE “FUND”)

SUPPLEMENT DATED AUGUST 6, 2021

TOTHE FUND’S PROSPECTUSAND STATEMENTOF ADDITIONAL

INFORMATION (“SAI”) DATED JULY 28, 2021

Effective August 6, 2021, the Fund’s Board of Trustees has eliminated the following investment policy with respect to the Fund:

“With respect to call options written on individual securities, the Fund will not write “naked” or uncovered call options.”

As such, any references in the Fund’s Prospectus and SAI to the aforementioned policy have been removed, effective immediately. Also effective immediately, all references throughout the Prospectus and SAI to “covered call options” written by the Fund have been replaced with “call options.”

PLEASE KEEP THIS WITH THE

FUND’S PROSPECTUS AND SAI

FOR FUTURE REFERENCE