Exhibit 99.3

  Guggenheim Securities, LLC 330 Madison Avenue New York, New York 10017 GuggenheimPartners.com

June 14, 2023

The Board of Directors

Spectrum Pharmaceuticals, Inc.

Pilot House – Lewis Wharf, 2 Atlantic Avenue, 6th Floor

Boston, MA 02110

Re: Consent for Fairness Opinion Disclosure

Members of the Board:

Guggenheim Securities, LLC (“Guggenheim Securities”) hereby consents to (i) the inclusion of our opinion letter dated April 24, 2023 (the “Opinion”) to the Board of Directors of Spectrum Pharmaceuticals, Inc. (“Spectrum”) as Annex E to the joint proxy statement/prospectus that is being filed on or promptly after the date hereof with the Securities and Exchange Commission in connection with the proposed merger involving Spectrum and Assertio Holdings, Inc. (“Assertio”), which joint proxy statement/prospectus forms a part of the Registration Statement on Form S-4 of Assertio (the “Registration Statement”) that is being filed on or promptly after the date hereof with the Securities and Exchange Commission, (ii) the references therein to Guggenheim Securities and (iii) the inclusion therein of (a) the summaries of and excerpts from the Opinion, (b) the description of certain financial analyses underlying the Opinion and (c) certain terms of our engagement by Spectrum.

By giving such consent, Guggenheim Securities does not thereby admit that we are experts with respect to any part of such joint proxy statement/prospectus within the meaning of the term “expert” as used in, or that we come within the category of persons whose consent is required under, the Securities Act of 1933 or the Securities Exchange Act of 1934, each as amended, or the rules and regulations of the Securities and Exchange Commission promulgated thereunder.

Very truly yours,
GUGGENHEIM SECURITIES, LLC
By:	/s/ Eric Rutkoske
	Eric Rutkoske
	Senior Managing Director