Phio Pharmaceuticals Corp

Table of Contents

As filed with the Securities and Exchange Commission on January 21, 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)

11 Apex Drive, Suite 300A, PMB 2006

Marlborough, Massachusetts 01752

(508)767-3861

(Address, including zip code, and telephone number, including area code, of Registrant’s principal executive offices)

Robert J. Bitterman

President & CEO

Phio Pharmaceuticals Corp.

11 Apex Drive, Suite 300A, PMB 2006

Marlborough, Massachusetts 01752

(508) 767-3861

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Steven J. Abrams, Esq.

Hogan Lovells US LLP

1735 Market Street, Suite 2300

Philadelphia, Pennsylvania 19103

(267) 675-4600

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, 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.☐

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, 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 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.☐

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, as amended, or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information in this preliminary prospectus is not complete and may be changed. These securities may not be sold 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 it is not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

Subject to completion, dated January 21, 2025

Preliminary Prospectus

Up to 5,930,016 Shares of Common Stock

Pursuant to this prospectus, the selling stockholders identified herein (the “Selling Stockholders”) are offering on a resale basis an aggregate of up to 5,930,016 shares of common stock of Phio Pharmaceuticals Corp. (the “Company,” “we,” “us” or “our”), par value $0.0001 per share (the “Common Stock) consisting of (a) up to 437,192 shares of Common Stock that are issuable upon exercise of warrants with a five year term (the “Series E Warrants”) purchased pursuant to a securities purchase agreement by and among the Company and certain of the Selling Stockholders, dated December 19, 2024, (b) up to 240,000 shares of Common Stock that are issuable upon exercise of warrants with a five year term (the “Series F Warrants”) purchased pursuant to a securities purchase agreement by and among the Company and certain of the Selling Stockholders, dated December 23, 2024, (c) up to 2,127,340 shares of Common Stock that are issuable upon exercise of warrants with a twenty-four month term (the “Series G Warrants”) purchased pursuant to a securities purchase agreement by and among the Company and certain of the Selling Stockholders, dated January 13, 2025, (d) up to 1,666,670 shares of Common Stock that are issuable upon exercise of warrants with a twenty-four month term (the “Series H Warrants”) purchased pursuant to a securities purchase agreement by and among the Company and certain of the Selling Stockholders, dated January 14, 2025, (e) up to 1,220,000 shares of Common Stock that are issuable upon exercise of warrants with a twenty-four month term (the “Series I Warrants”) purchased pursuant to a securities purchase agreement by and among the Company and certain of the Selling Stockholders, dated January 16, 2025 and (f) up to 238,814 shares of Common Stock that are issuable upon the exercise of certain warrants (together with the Series E Warrants, the Series F Warrants, the Series G Warrants, the Series H Warrants and the Series I Warrants, the “Warrants”) issued to our placement agent pursuant to an engagement letter in connection with the offerings described herein.

We will not receive any of the proceeds from the sale by the Selling Stockholders of the Common Stock covered by this prospectus. Upon any exercise of the Warrants by payment of cash, however, we will receive the exercise price of the Warrants, which, if exercised in cash with respect to the 5,930,016 shares of Common Stock offered hereby, would result in gross proceeds to us of approximately $17.5 million. However, we cannot predict when and in what amounts or if the Warrants will be exercised by payments of cash and it is possible that the Warrants may expire and never be exercised, in which case we would not receive any cash proceeds.

The Selling Stockholders may sell or otherwise dispose of the Common Stock covered by this prospectus in a number of different ways and at varying prices. We provide more information about how the Selling Stockholders may sell or otherwise dispose of the Common Stock covered by this prospectus in the section entitled “Plan of Distribution” on page 50. Discounts, concessions, commissions and similar selling expenses attributable to the sale of Common Stock covered by this prospectus will be borne by the Selling Stockholders. We will pay all expenses (other than discounts, concessions, commissions and similar selling expenses) relating to the registration of the Common Stock with the Securities and Exchange Commission (the “SEC”).

Our Common Stock is listed on The Nasdaq Capital Market under the symbol “PHIO.” On January 17, 2025, the last reported sale price of our Common Stock on The Nasdaq Capital Market was $2.77 per share.

Investing in our securities involves a high degree of risk. Before making any investment in these securities, you should consider carefully the risks and uncertainties described in the section entitled “Risk Factors” beginning on page 10 of this prospectus.

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