Post-Effective Amendment to Post-Effective Amendment by Investment Company (Form 485BXT)

As filed with the U.S. Securities and Exchange Commission on June 12, 2026

File No. 333-271700

File No. 811-23872

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933		☒
	Pre-Effective Amendment No.	☐
	Post-Effective Amendment No. 255	☒
and/or
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940		☒
	Amendment No. 257	☒

Themes ETF Trust

(Exact Name of Registrant as Specified in Charter)

34 East Putnam Avenue, Suite 112

Greenwich, CT 06830

(Address of Principal Executive Offices, Zip Code)

(646) 206-1788

(Registrant's Telephone Number, including Area Code)

Jose C. Gonzalez

34 East Putnam Avenue, Suite 112

Greenwich, CT 06830

(Name and Address of Agent for Service)

Copy to:

Karen Aspinall, Esq.

Practus, LLP

11300 Tomahawk Creek Parkway, Suite 310

Leawood, Kansas 66211

[email protected]

It is proposed that this filing will become effective (check appropriate box):

	☐	immediately upon filing pursuant to paragraph (b)
	☒	On July 12, 2026, pursuant to paragraph (b)
	☐	60 days after filing pursuant to paragraph (a)(1)
	☐	on pursuant to paragraph (a)(1)
	☐	75 days after filing pursuant to paragraph (a)(2)
	☐	on _____________ pursuant to paragraph (a)(2) of Rule 485.

If appropriate, check the following box

☒

this post-effective amendment designates a new effective date for a previously filed post-effective amendment.

EXPLANATORY NOTE

The sole purpose of this filing is to delay the effectiveness of Post-Effective Amendment No. 147 (the "Amendment") to the Registrant's Registration Statement (filed on March 30, 2026) with respect to 3 of its proposed series (Leverage Shares Long Bitcoin Volatility Daily ETF, Leverage Shares 2X Long Bitcoin Volatility Daily ETF, and Leverage Shares -1X Short Bitcoin Volatility Daily ETF) until July 12, 2026. Parts A and B of the Amendment are incorporated by reference herein. This amendment also incorporates by reference the information contained in Part C of Post-Effective Amendment No. 254 to the Registrant's Registration Statement, which was filed on June 12, 2026.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 (the "Securities Act") and the Investment Company Act of 1940, the Trust certifies that it meets all of the requirements for effectiveness of this Post-Effective Amendment to its Registration Statement on Form N-1A under Rule 485(b) under the Securities Act and has duly caused this Post-Effective Amendment No. 255 to the Registrant's Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of Greenwich, State of Connecticut, on this 12^th day of June, 2026.

THEMES ETF TRUST
By:	/s/ Jose C. Gonzalez
	Jose C. Gonzalez
	Trustee and President (Principal Executive Officer)

Pursuant to the requirements of the Securities Act, this Registration Statement has been signed below by the following persons in the capacities and on the dates indicated.

Signature		Title		Date
/s/ Jose C. Gonzalez		Trustee and President		June 12, 2026
Jose C. Gonzalez		(Principal Executive Officer)
/s/ Dobromir Kamburov		Treasurer		June 12, 2026
Dobromir Kamburov*		(Principal Financial Officer and Principal Accounting Officer)
/s/ Sanjay R. Bharwani		Trustee		June 12, 2026
Sanjay R. Bharwani*
/s/ Neil Fleming		Trustee		June 12, 2026
Neil Fleming*
/s/ Tracy N. Packwood		Trustee		June 12, 2026
Tracy N. Packwood*

*By:	/s/ Jose C. Gonzalez
	Jose C. Gonzalez

Attorney-in-Fact pursuant to Powers of Attorney previously filed with Pre-Effective Amendment No. 2 to the Registrant's registration statement on November 9, 2023.