Boost Run Inc.

As filed with the Securities and Exchange Commission on July 2, 2026.

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)

**5 Revere Drive, Suite 200 **

Northbrook, IL 60062

(847) 489-3367

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

Andrew Karos

**5 Revere Drive, Suite 200 **

Northbrook, IL 60062

(847) 489-3367

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

Copies of all communications, including communications sent to agent for service, should be sent to:

Michael Blankenship, Esq.

Beniamin Smolij, Esq.

Winston Taylor LLP

800 Capitol St Suite 2400

Houston, TX 77002

(713) 651-2600

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, 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, 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(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 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 prospectus is not an offer to sell nor does it seek an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED JULY 2, 2026

PRELIMINARY PROSPECTUS

58,738,753** Shares of Class A Common Stock**

**(Inclusive of 29,533,018 shares of Class A Common Stock Issuable Upon Conversion of Class B Common Stock, 4,007,216 shares of Class A Common Stock Underlying Private Warrants, 14,229,769 Shares of Class A Common Stock held by Certain

Selling Holders and 10,968,750 Earnout Shares)

4,007,216** Warrants to Purchase Shares of Class A Common Stock**

This prospectus relates to the offer and sale, from time to time, by the selling holders identified in this prospectus (collectively, the “Selling Holders”), or their permitted transferees, of (i) up to 9,601,095 shares of our Class A common stock, par value $0.0001 (“Class A Common Stock”), held by certain Selling Holders who received such shares in connection with the Business Combination, (ii) up to 4,628,674 shares of Class A Common Stock issued to the Sponsor and its distributees in exchange for the Founder Shares purchased prior to the Willow Lane IPO, (iii) up to 4,007,216 shares of Class A Common Stock underlying warrants to purchase shares of Class A Common Stock held by certain Selling Holders (the “Private Warrants”), (iv) up to 29,533,018 shares of Class A Common Stock issuable upon the conversion of 29,533,018 shares of our Class B common stock, par value $0.0001 per share (“Class B Common Stock” and, together with the Class A Common Stock, the “Common Stock”), held by certain Selling Holders, (v) up to 10,968,750 shares of Class A Common Stock issued as earnout consideration (the “Earnout Shares”), consisting of up to 7,875,000 shares of Class A Common Stock issuable to Andrew Karos and up to 3,093,750 shares of Class A Common Stock issuable to the Sponsor and the SPV pursuant to the Earnout Agreement (as defined below), and (vi) 4,007,216 Private Warrants held by certain Selling Holders. The shares of Class A Common Stock and Private Warrants that may be sold by the Selling Holders are collectively referred to in this prospectus as the “Offered Securities.” We will not receive any of the proceeds from the sale by the Selling Holders of the Offered Securities.

We will receive all of the proceeds from the exercise of the Private Warrants for cash, if any, to the extent they are exercised for cash. We believe the likelihood that the Selling Holders will exercise their Private Warrants, and therefore the amount of cash proceeds that we would receive, is dependent upon the trading price of our Class A Common Stock. If the trading price for our Class A Common Stock is less than $11.50 per share, we believe holders of our Private Warrants are unlikely to exercise their Private Warrants. Conversely, these holders are more likely to exercise their Private Warrants the higher the price of our Class A Common Stock is above $11.50 per share. The Private Warrants are exercisable on a cashless basis under certain circumstances specified in the Warrant Agreement (as defined herein). To the extent that any Private Warrants are exercised on a cashless basis, the aggregate amount of cash we would receive from the exercise of the Private Warrants will decrease.

We will bear all costs, expenses and fees in connection with the registration of Offered Securities. The Selling Holders will bear all commissions and discounts, if any, attributable to their respective sales of Offered Securities. We are registering the Offered Securities for sale by certain of the Selling Holders pursuant to registration rights agreements with certain of the Selling Holders. See the section of this prospectus titled “Selling Holders” for more information.

The Selling Holders may offer and sell the Offered Securities owned by them covered by this prospectus from time to time. The Selling Holders may offer and sell the Offered Securities owned by them covered by this prospectus in a number of different ways and at varying prices. If any underwriters, dealers or agents are involved in the sale of any of the securities, their names and any applicable purchase price, fee, commission or discount arrangement between or among them will be set forth, or will be calculable from the information set forth, in any applicable prospectus supplement. See the sections of this prospectus titled “About this Prospectus” and “Plan of Distribution” for more information. No securities may be sold without delivery of this prospectus and any applicable prospectus supplement describing the method and terms of the offering of such securities. You should carefully read this prospectus and any applicable prospectus supplement before you invest in our securities.

The Offered Securities being offered by the Selling Holders were purchased by the Selling Holders at, or are exercisable at, various prices, certain of which are below the current trading price of our Class A Common Stock. The sale or the possibility of the sale of the Offered Securities being offered pursuant to this prospectus may negatively impact the market price of the Class A Common Stock.

The Class A Common Stock being offered for resale in this prospectus (including the shares of Class A Common Stock underlying the Class B Common Stock and the Private Warrants) represent approximately 77% of our total outstanding Common Stock on a fully diluted basis as of July 2, 2026. The sale of all the securities being offered in this prospectus could result in a significant decline in the public trading price of our Class A Common Stock. Despite such a decline in the public trading prices, the Selling Holders may still experience a positive rate of return on the securities they purchased due to the differences in the trading price and the purchase prices at which they purchased the securities as described herein. See “Risk Factors - Future sales, or the perception of future sales, of our Class A Common Stock by us or our stockholders in the public market could cause the market price for our Class A Common Stock to decline” and “Risk Factors - Certain existing securityholders acquired their securities in the Company at prices below the current trading price of such securities, and may experience a positive rate of return based on the current trading price. Future investors in our Company may not experience a similar rate of return.”

We are a “controlled company” within the meaning of the listing rules of The Nasdaq Stock Market, LLC (“Nasdaq”). As a controlled company, we are exempt from certain Nasdaq governance requirements that otherwise apply to the composition and function of our board of directors (the “Board”). As a result, (i) our Board does not have a majority of independent directors, (ii) the compensation of our executive officers is not determined by a majority of the independent directors or a committee of independent directors, and (iii) director nominees are not selected or recommended by a majority of the independent directors or a committee of independent directors. As of July 1, 2026, Andrew Karos beneficially owned approximately 90% of the voting power of our outstanding Common Stock. If at any time we cease to be a controlled company, we will take all action necessary to comply with the listing rules of Nasdaq, including appointing a majority of independent directors to our Board and ensuring our compensation committee and nominating and corporate governance committee are each composed entirely of independent directors, subject to any permitted “phase-in” periods.

Our Class A Common Stock is listed on Global Market tier of Nasdaq under the symbol “BRUN.” On June 30, 2026, the last reported sales price of the Class A Common Stock was $38.81 per share. We are an “emerging growth company” as defined under U.S. federal securities laws and, as such, may elect to comply with certain reduced public company reporting requirements for this and future filings. The closing price of our warrants on the Capital Market tier of Nasdaq was $27.18 on June 30, 2026.

See “Risk Factors” beginning on page 13 to read about factors you should consider before investing in shares of our Class A Common Stock and Warrants.

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 this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is , 2026