QT IMAGING HOLDINGS, INC.

As filed with the U.S. Securities and Exchange Commission on November 3, 2025.

Registration No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORMS-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

(Exact Name of Registrant as Specified in its Charter)

Dr. Raluca Dinu

Chief Executive Officer

3 Hamilton Landing, Suite 160,

Novato, CA 94949

Telephone: (650) 276-7040

(Address, Including Zip Code, and Telephone Number, Including Area Code, of Registrant’s Principal Executive Offices)

(Name, Address, Including Zip Code, and Telephone Number, Including Area Code, of Agent for Service)

Copies to:

Jeffrey C. Selman

Elena Nrtina

DLA Piper LLP (US)

555 Mission Street, Suite 2400

San Francisco, California 94105

Tel: (415) 615-6035

Approximate date of commencement of proposed sale to the public: From time to time 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, please 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, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

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. o

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. o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a 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 under the Securities Exchange Act of 1934:

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. o

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with section 8(a) of the Securities Act of 1933 or until the registration statement shall become effective on such date as the Commission acting pursuant to said section 8(a), may determine.

The information in this preliminary prospectus is not complete and may be changed. Neither we nor the Selling Securityholders may sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This preliminary prospectus is not an offer to sell these securities and is not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

PRELIMINARY PROSPECTUS

SUBJECT TO COMPLETION-DATED NOVEMBER 3, 2025

29,336,017 Shares of Common Stock

This prospectus relates solely to the offer and sale from time to time of up to an aggregate 29,336,017 shares of the common stock, par value $0.0001 per shares (the “Common Stock”), of QT Imaging Holdings, Inc. (the “Company,” “we,” “our” or “us”) by the selling securityholders identified in this prospectus (the “Selling Securityholders”). Such shares consist of (i) 2,562,334 shares of Common Stock that have been issued to the Selling Securityholders (the “Common Shares”), (ii) 24,442,342 shares of Common Stock that are issuable upon the exercise of the Five Year Common Warrants (as defined below) acquired by certain of the Purchasers (as defined below) and Lynrock Lake Master Fund LP (“Lynrock Lake”), (iii) 523,286 shares of Common Stock that are issuable upon the exercise of the Common Stock purchase warrants with a term of ten years from the initial exercise date (the “Ten Year Common Warrants”) acquired by certain of the Purchasers and (iv) 1,808,055 shares of Common Stock that are issuable upon the exercise of the pre-funded warrants (the “Pre-Funded Warrants”, and together with the Five Year Common Warrants and the Ten Year Common Warrants, the “Warrants”) acquired by certain of the Purchasers and exercisable any time after its issuance. The shares of Common Stock issuable upon the exercise of the Warrants are referred to as the “Warrant Shares.”

On August 19, 2025, the Company held its 2025 Annual Meeting of Stockholders (the “Annual Meeting”). At the Annual Meeting, the Company’s stockholders approved an amendment to the Company’s Second Amended and Restated Certificate of Incorporation (the “Certificate of Amendment”) to effect a reverse split of the outstanding shares of the Common Stock at a specific ratio within a range of 2:1 to 20:1, with the specific ratio to be fixed within this range by the Company’s board of directors (the “Board”) in its sole discretion without further stockholder approval (the “Reverse Stock Split”). On October 17, 2025, the Board determined to fix the Reverse Stock Split ratio at 3:1. The Reverse Stock Split became effective as of 4:01 p.m., Eastern Time, on October 23, 2025 (the “Effective Time”), upon the filing of the Certificate of Amendment with the Secretary of State of the State of Delaware.

On February 26, 2025, the Company entered into a credit agreement (the “Credit Agreement”) with Lynrock Lake that provided a senior secured term loan with Lynrock Lake in the aggregate principal amount of $10,100,000 at an interest rate of 10.0% per annum. On August 26, 2025, the Company and Lynrock Lake entered into the First Amendment to the Credit Agreement (the “Amended Credit Agreement”) to add an additional tranche of $5,000,000 to the loan and increase the aggregate principal amount to $15,100,000. In connection with the Credit Agreement, the Company and Lynrock Lake entered into a Warrant Agreement, dated February 26, 2025, as amended (the “Warrant Agreement”), pursuant to which Lynrock Lake holds a warrant, which prior to the implementation of the Reverse Stock Split, was a warrant to purchase 61,000,000 shares of Common Stock at an exercise price of $0.40 per share (the “Lynrock Lake Warrant”), which since the Effective Time, both the number of shares to be issued upon exercise of the Lynrock Lake Warrant and the exercise price have been adjusted to 20,333,623 and $1.20, respectively.

On April 9, 2025, the Company completed a private placement (the “First Private Placement”), pursuant to the terms and conditions of the Securities Purchase Agreement, dated April 9, 2025 (the “First Securities Purchase Agreement”), by and between the Company and Dr. Avi Katz, the Chairman of the Company’s Board of Directors, and Dr. Raluca Dinu, the Chief Executive Officer and a member of the Company’s Board of Directors, on the other hand, (together, the “First Purchasers”), pursuant to which the First Purchasers purchased and the Company issued, (i) using amounts from prior to the implementation of the Reverse Stock Split, 784,929 Common Shares, and following the Reverse Stock Split, 261,644 Common Shares and (ii) the Ten Year Common Warrants, which following the Reverse Stock Split have an exercise price of $2.16 per share and are exercisable for an aggregate of 523,286 shares of Common Stock. Pursuant to the First Securities Purchase Agreement, the Company entered into a Registration Rights Agreement with the First Purchasers, dated April 9, 2025 (the “First Registration Rights Agreement”). The aggregate gross proceeds to the Company from the First Private Placement were approximately $500,000, before deducting the placement agent fees and other offering expenses payable by the Company. See the section entitled “Private Placement of Shares of Common Stock and Warrants.”

On May 12, 2025, the Company completed a private placement (the “Second Private Placement”), pursuant to the terms and conditions of the Securities Purchase Agreement, dated May 12, 2025 (the “Second Securities Purchase Agreement”), by and between the company and Leon Recanati (the “Second Purchaser”), pursuant to which the Second Purchaser purchased and the Company issued using amounts from prior to the implementation of the Reverse Stock Split (i) 205,339 Common Shares (and following the Reverse Stock Split, 68,447 Common Shares) and (ii) a Common Stock Purchase Warrant (the “Recanati Warrant”) with a term of five years from the initial exercise date to purchase up to an additional 205,339 shares of Common Stock, which since the Effective Time, the number of shares to be issued upon exercise of the Recanati Warrant has been adjusted to 68,447. Pursuant to the Second Securities Purchase Agreement, the Company entered into a Registration Rights Agreement with the Second Purchaser, dated May 12, 2025 (the “Second Registration Rights Agreement”). The aggregate gross proceeds to the Company from the Second Private Placement were approximately $200,000, before deducting the placement agent fees and other offering expenses payable by the Company. See the section entitled “Private Placement of Shares of Common Stock and Warrants.”

On October 3, 2025, the Company completed a private placement (the “Third Private Placement”), pursuant to the terms and conditions of the Securities Purchase Agreement, dated September 30, 2025 (the “Third Securities Purchase Agreement”), by and between the Company and certain accredited investors and qualified institutional buyers, led by Sio Capital Management, LLC, (the “Third Purchasers”, and together with the First Purchasers and Second Purchaser, the “Purchasers”), pursuant to which the Third Purchasers purchased in the aggregate and the Company issued using amounts from prior to the implementation of the Reverse Stock Split (i) 6,696,715 Common Shares (and following the Reverse Stock Split, 2,232,243 Common Shares), (ii) Subscription Warrants (the “Subscription Warrants”, and together the Lynrock Lake Warrant and the Recanati Warrant, the “Five Year Common Warrants”) with a term of five years from the initial exercise date to purchase up to an additional 12,120,798 shares of Common Stock, which since the Effective Time, the number of shares to be issued upon exercise of the Subscription Warrants have been adjusted to 4,040,272, and (iii) up to 5,424,083 Pre‑Funded Warrants to purchase up to an additional 5,424,083 shares of Common Stock, which since the Effective Time, the number of shares to be issued upon exercise of the Pre-Funded Warrants have been adjusted to 1,808,055. Pursuant to the Third Securities Purchase Agreement, the Company entered into a Registration Rights Agreement with the Third Purchasers, dated September 30, 2025 (the “Third Registration Rights Agreement”, and together with the First Registration Rights Agreement and Second Registration Rights Agreement, the “Registration Rights Agreements”). The aggregate gross proceeds to the Company from the Third Private Placement were approximately $18,180,655, before deducting the placement agent fees and other offering expenses payable by the Company. See the section entitled “Private Placement of Shares of Common Stock and Warrants.”

The Company is registering the Common Shares and Warrant Shares for resale pursuant to the Registration Rights Agreements and the Warrant Agreement. The Company will not receive any of the proceeds from the sale of these shares of Common Stock by the Selling Securityholders. However, the Company will receive proceeds from the exercise of the Warrants, if the Warrants are exercised for cash. The Company intends to use those proceeds, if any, for general corporate purposes. All fees and expenses incident to the Company’s performance of or compliance with the Registration Rights Agreements will be borne by the Company, whether or not any Common Shares or Warrant Shares are sold pursuant to a registration statement. The Selling Securityholders will pay any broker commissions or similar commissions or fees incurred for the sale of these shares of Common Stock.

The Selling Securityholders may offer such shares from time to time as it may determine through public or private transactions or through other means described in the section entitled “Plan of Distribution” beginning on page 196) of this prospectus, at prevailing market prices or at privately negotiated prices. This prospectus does not necessarily mean that the Selling Securityholders will offer or sell the Common Shares or Warrant Shares. The Company cannot predict when or in what amounts the Selling Securityholders may sell any of the shares offered by this prospectus. Any shares of Common Stock subject to resale hereunder will have been issues by the Company and acquired by the Selling Securityholders prior to any resale of such shares pursuant to this prospectus.

Because all of the shares of Common Stock offered under this prospectus are being offered by the Selling Securityholders, the Company cannot currently determine the price or prices at which the Company’s shares may be sold under this prospectus.

Sales of a substantial number of shares of Common Stock in the public market, including the resale of the PIPE Shares held by our stockholders pursuant to this prospectus or pursuant to Rule 144, could occur at any time. These sales, or the perception in the market that the holders of a large number of shares of Common Stock intend to sell shares, could reduce the market price of the Common Stock and make it more difficult for you to sell your holdings at times and prices that you determine are appropriate. Shares of Common Stock held by certain of our stockholders, including the Selling Securityholders, were purchased at an effective price lower than the current market price of our Common Stock. Accordingly, such stockholders could sell their securities at a per-share price that is less than the purchase price other stockholders paid and still realize a significant profit from the sale of those securities that could not be realized by our other stockholders. Furthermore, we expect that, because there is a large number of shares being registered pursuant to the registration statement of which this prospectus forms a part, the Selling Securityholders will continue to offer the securities covered thereby pursuant to this prospectus or pursuant to Rule 144 for a significant period of time, the precise duration of which cannot be predicted. Accordingly, the adverse market and price pressures resulting from an offering pursuant to the registration statement may continue for an extended period of time.

You should read this prospectus and any prospectus supplement of amendment carefully before you invest in our securities. Our Common Stock are traded in the over-the-counter (OTC) Market OTCQB under the symbol “QTIH,” and our Public Warrants are traded in the OTC market under the symbol “QTIWW.” On [ ], 2025, the closing price of our Common Stock was $[ ], and on [ ], 2025, the closing price for our Public Warrants was $[ ].

We are an “emerging growth company” as defined in Section 2(a) of the Securities Act of 1933, as amended, and are subject to reduced public company reporting requirements. This prospectus complies with the requirements that apply to an issuer that is an emerging growth company.

See the section entitled “Risk Factors” beginning on page 17 of this prospectus to read about factors you should consider before buying our securities.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is [ ], 2025.

You should rely only on the information provided in this prospectus, as well as the information incorporated by reference into this prospectus and any applicable prospectus supplement. Neither we nor the Selling Securityholders have authorized anyone to provide you with different information. Neither we nor the Selling Securityholders are making an offer of these securities in any jurisdiction where the offer is not permitted. You should not assume that the information in this prospectus or any applicable prospectus supplement is accurate as of any date other than the date of the applicable document. Since the date of this prospectus and the documents incorporated by reference into this prospectus, our business, financial condition, results of operations and prospects may have changed.

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