Filed pursuant to Rule 424(b)(3)
Registration No. 333-243483
PROSPECTUS SUPPLEMENT NO. 9
(to prospectus dated
August 27, 2020)
Summit Midstream Partners, LP
666,667 Common Units
Representing Limited Partner Interests
This prospectus supplement is being filed to update and supplement information contained in the prospectus dated August 27, 2020 (the
prospectus), relating to up to 666,667 common units representing limited partner interests in Summit Midstream Partners, LP (10,000,000 common units prior to the Partnerships 1-for-15 reverse unit split on its common units, effective after the market closed on November 9, 2020) to be offered on a secondary basis by the selling unitholders named in the prospectus, with
information contained in our Current Report on Form 8-K, filed with the Securities and Exchange Commission on April 15, 2021, which is set forth below.
This prospectus supplement updates and supplements the information in the prospectus and is not complete without, and may not be delivered or
utilized except in combination with, the prospectus, including any amendments or supplements thereto. This prospectus supplement should be read in conjunction with the prospectus and if there is any inconsistency between the information in the
prospectus and this prospectus supplement, you should rely on the information in this prospectus supplement.
Investing in our
securities involves a high degree of risk. Limited partnerships are inherently different from corporations. You should review carefully the risk factors described under
Risk Factors beginning on page 6 of the prospectus for a discussion of important risks you should consider before you make an investment in our securities.
Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or
determined if the prospectus is truthful or complete. Any representation to the contrary is a criminal offense.
The date of this
prospectus supplement is April 15, 2021.