Chapman and Cutler LLP 320 South Canal Street Chicago, IL 60606   T 312.845.3000 F 312.701.2361 www.chapman.com

October 13, 2026

U.S. Securities and Exchange Commission

100 F Street, N.E.

Washington, DC 20549

Ladies and Gentlemen:

On behalf of REX ETF Trust (the “Registrant”), in accordance with the provisions of Rule 497(j) of Regulation C under the Securities Act of 1933 (the “Securities Act”), this letter serves to certify that the most recent amendment to the Registration Statement on Form N-1A (the “Registration Statement”) of the Registrant and its series, REX Peptide ETF, does not differ from that which would have been filed pursuant to Rule 497(c) of the Securities Act. Post-Effective Amendment No. 137, which was the most recent amendment to the Registration Statement, was filed electronically with the Securities and Exchange Commission on October 9, 2026.

If you have any questions or comments, please telephone the undersigned at (312) 845-3484.

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