As filed with the U.S. Securities and Exchange Commission on February 8, 2021.

Registration No. 333-          

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM S-1
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

Approximate date of commencement of proposed sale to the public:

As soon as practicable after the effective date of this registration statement

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box. ☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☒ 333-252162

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

CALCULATION OF REGISTRATION FEE

THE REGISTRATION STATEMENT SHALL BECOME EFFECTIVE UPON FILING WITH THE SECURITIES AND EXCHANGE COMMISSION IN ACCORDANCE WITH RULE 462(B) UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

EXPLANATORY NOTE

This Registration Statement on Form S-1 (this “Registration Statement”) is being filed with respect to the registration of 9,200,000 additional units of Spartan Acquisition Corp. III, a Delaware corporation (the “Registrant”), each consisting of one share of Class A common stock, par value $0.0001 (“Class A Common Stock”), and one-fourth of one redeemable warrant, pursuant to Rule 462(b) under the Securities Act of 1933, as amended, and General Instruction V to Form S-1, including 1,200,000 units that may be purchased by the underwriters to cover over-allotments, if any. Each whole warrant entitles the holder thereof to purchase one share of Class A Common Stock at a price of $11.50 per share, subject to adjustment, and only whole warrants are exercisable. No fractional warrants will be issued upon separation of the units and only whole warrants will trade. This Registration Statement relates to the Registrant’s Registration Statement on Form S-1, as amended (File No. 333-252162) (the “Prior Registration Statement”), initially filed by the Registrant on January 15, 2021 and declared effective by the U.S. Securities and Exchange Commission on February 8, 2021. The required opinion of counsel and related consent and accountant’s consent are attached hereto and filed herewith. Pursuant to Rule 462(b), the contents of the Prior Registration Statement, including the exhibits thereto, are incorporated by reference into this Registration Statement.

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

(a)Exhibits. All exhibits filed with or incorporated by reference in the Prior Registration Statement on Form S-1 (File No. 333-252162) are incorporated by reference into, and shall be deemed a part of, this Registration Statement, and the following additional exhibits are filed herewith, as part of this Registration Statement:

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SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the registrant has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of New York, New York on the 8th day of February, 2021.

Spartan Acquisition Corp. III

Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed below by the following persons in the capacities indicated and on the dates indicated.

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