SNII Supernova Partners Acquisition Company II Ltd

Filed Pursuant to Rule 424(b)(3)

Registration No. 333-263798

PROSPECTUS SUPPLEMENT NO. 6

(To Prospectus dated June 1, 2022)

UP TO 19,354,059 SHARES OF COMMON STOCK

ISSUABLE UPON EXERCISE OF WARRANTS

UP TO 96,941,181 SHARES OF COMMON STOCK

UP TO 4,450,000 WARRANTS TO PURCHASE COMMON STOCK

This prospectus supplement supplements the prospectus, dated June 1, 2022 (the “Prospectus”), which forms a part of our registration statement on Form S-1 (No. 333-263798). This prospectus supplement is being filed to update and supplement the information in the Prospectus with the information contained in Item 5.02 of our Current Report on Form 8-K filed with the Securities and Exchange Commission on November 9, 2022 (the “Current Report”). Accordingly, we have attached the Current Report to this prospectus supplement.

The Prospectus and this prospectus supplement relate to the issuance by us of up to an aggregate of 19,354,059 shares of our common stock, $0.0001 par value per share (the “common stock”) consisting of (i) 4,450,000 shares of common stock issuable upon the exercise of 4,450,000 warrants (the “private placement warrants”) originally issued in a private placement in connection with the initial public offering (the “IPO”) of Supernova Partners Acquisition Company II, Ltd., a Cayman Islands exempted company (“Supernova”), by the holders thereof, (ii) 8,624,972 shares of common stock issuable upon the exercise of 8,624,972 warrants (the “public warrants” and, together with the private placement warrants, the “warrants”) originally issued in the IPO by holders thereof, and (iii) 6,279,087 shares of common stock issuable upon the exercise of warrants assumed by us and converted into warrants to purchase common stock (the “Rigetti assumed warrants”) in connection with the Business Combination (as defined below). We will receive the proceeds from the exercise of any warrants and any Rigetti assumed warrants for cash.

The Prospectus and this prospectus supplement also relate to the offer and sale from time to time by the selling securityholders named in this prospectus or their permitted transferees (the “selling securityholders”) of up to (i) 96,941,181 shares of common stock consisting of (a) 10,251,000 shares of common stock purchased by subscribers at a price of $10.00 per share and 4,390,244 shares of common stock purchased by subscribers at a price of $10.25 per share in private placements pursuant to separate subscription agreements, (b) 8,625,000 shares of common stock (the “Founder Shares”) originally purchased by Supernova Partners II LLC (“Supernova Sponsor”) for $25,000, or for approximately $0.004 per share, in a private placement in connection with the IPO, including 3,059,273 Founder Shares subject to vesting and forfeiture (the “Sponsor Vesting Shares”), (c) 4,450,000 shares of common stock issuable upon exercise of the private placement warrants, (d) 2,446,716 shares of common stock issuable pursuant to the exercise of Rigetti assumed warrants, which Rigetti assumed warrants have a weighted average exercise price of $0.6628 per share, (e) 6,226,065 shares of common stock issuable upon exercise of outstanding options, which have an exercise price of $0.272 per share, (f) 6,288,369 shares of common stock issuable in connection with the vesting and settlement of outstanding restricted stock units, which were assumed by and converted into restricted stock awards for common stock in connection with the Business Combination based on an acquiror share value of $10.00 per share and (g) 54,263,787 shares of common stock issued in connection with the Business Combination as merger consideration at an acquiror share value of $10.00 per share, and (ii) up to 4,450,000 private placement warrants, which were purchased by Supernova Sponsor at a price of $2.00 per warrant. We will not receive any proceeds from the sale of shares of common stock or warrants by the selling securityholders pursuant to this prospectus.

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 is qualified by reference to the Prospectus, including any amendments or supplements thereto, except to the extent that the information in this prospectus supplement updates and supersedes the information contained therein.

Our common stock and public warrants are listed on the Nasdaq Capital Market under the symbols “RGTI” and “RGTIW,” respectively. On November 8, 2022, the last reported sales price of our common stock was $1.57 per share and the last reported sales price of our public warrants was $0.1836 per warrant.

We are an “emerging growth company” as defined under U.S. federal securities laws and, as such, have elected to comply with reduced public company reporting requirements. The Prospectus complies with the requirements that apply to an issuer that is an emerging growth company.

Investing in our securities involves a high degree of risks. You should review carefully the risks and uncertainties described in the section titled “Risk Factors” beginning on page 16 of the Prospectus, and under similar headings in any amendments or supplements to the Prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities, or passed upon the accuracy or adequacy of the Prospectus or this prospectus supplement. Any representation to the contrary is a criminal offense.

Prospectus Supplement dated November 9, 2022.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): November 7, 2022

(510) 210-5550

(Registrant’s telephone number, including area code)

N/A

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligations of the registrant under any of the following provisions:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ☒

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 13(a) of the Exchange Act.  ☐

On November 7, 2022, Chad Rigetti, Founder, President and Chief Executive Officer of Rigetti Computing, Inc. (the “Company”), provided the Company with his intention to tender resignation from his positions with the Company as President, Chief Executive Officer and Director on the Company’s Board of Directors, with an anticipated effective date of December 15, 2022.

As previously announced, the Company is conducting a search for Dr. Rigetti’s successor. In the event a successor is not identified and appointed before Dr. Rigetti’s resignation date, it is anticipated that Rick Danis, the Company’s General Counsel and Corporate Secretary, will serve as interim President and Chief Executive Officer of the Company effective as of such date until a successor to Dr. Rigetti has been appointed.

Mr. Danis, 53, has served as General Counsel and Corporate Secretary of Rigetti since immediately following the consummation of the Business Combination and served as Legacy Rigetti’s General Counsel and Corporate Secretary from July 2019 until the consummation of the Business Combination. Prior to joining Legacy Rigetti, Mr. Danis served as Chief Legal Officer and corporate secretary at Kymeta Corporation from May 2018 to July 2019. Mr. Danis also served as Senior Vice President and Assistant General Counsel at Funko from December 2017 to May 2018 and as General Counsel and Corporate Secretary at publicly traded Rightside Group, Ltd. from August 2014 until August 2017. In addition, Mr. Danis has served as a director on the board of F3 Nation, Inc. since January 2020. In all, Mr. Danis has over 25 years of experience practicing law, almost exclusively in-house at technology companies. Mr. Danis received a B.B.A. in accounting from Ohio University and a J.D. from DePaul University College of Law.

On November 9, 2022, the Company issued a press release with respect to the management transition described in Item 5.02 of this Current Report on Form 8-K. A copy of the Company’s press release is being furnished as Exhibit 99.1 to this Form 8-K. The exhibit attached hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended.