Issuer Free Writing Prospectus

Filed Pursuant to Rule 433

Dated September 15, 2026

Relating to Preliminary Prospectus Supplement Dated September 15, 2026

Registration Statement No. 333-293702

Common Stock

Pre-Funded Warrants to Purchase Shares of Common Stock

This free writing prospectus relates only to the public offering of shares of common stock and pre-funded warrants to purchase shares of common stock of Beta Bionics, Inc. and should be read together with the preliminary prospectus supplement, dated September 15, 2026 (the Preliminary Prospectus Supplement), and the accompanying prospectus, in each case, including the documents incorporated by reference therein. The information in this free writing prospectus updates and, to the extent inconsistent, supersedes the information in the Preliminary Prospectus Supplement. This free writing prospectus supplements the Preliminary Prospectus Supplement to reflect the addition of pre-funded warrants, and the shares of common stock issuable upon the exercise of such pre-funded warrants, to the securities being offered by Beta Bionics, Inc. Except as otherwise indicated, all information in this free writing prospectus and the Preliminary Prospectus Supplement assumes no exercise by the underwriters of their option to purchase additional shares of common stock and the full exercise of all pre-funded warrants sold in this offering.

This free writing prospectus is qualified in its entirety by reference to the Preliminary Prospectus Supplement and the accompanying prospectus, in each case, including the documents incorporated by reference therein. Financial information and other information presented in the Preliminary Prospectus Supplement or incorporated by reference therein is deemed to have changed to the extent affected by the changes described herein. This free writing prospectus should be read together with the Preliminary Prospectus Supplement and the accompanying prospectus, in each case, including the documents incorporated by reference therein, before making a decision in connection with an investment in the securities. Capitalized terms used in this free writing prospectus but not defined have the meanings given to them in the Preliminary Prospectus Supplement.

The offering

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Risk factors

There is no public market for the pre-funded warrants being offered by us in this offering.

There is no established public trading market for the pre-funded warrants being sold in this offering, and we do not expect a market to develop. In addition, we do not intend to apply to list the pre-funded warrants on any securities exchange or recognized trading system. Without an active market, the liquidity of the pre-funded warrants will be limited.

We will not receive any meaningful amount of additional funds upon the exercise of the pre-funded warrants; however, any exercise would increase the number of shares of our common stock eligible for future resale in the public market and result in dilution to our stockholders.

Each pre-funded warrant will be exercisable until it is fully exercised and by means of payment of the nominal cash purchase price upon exercise or by means of a “cashless exercise” according to a formula set forth in the pre-funded warrant. Accordingly, we will not receive any meaningful additional funds upon the exercise of the pre-funded warrants. To the extent such pre-funded warrants are exercised, additional shares of common stock will be issued for nominal or no additional consideration, which will result in dilution to the then existing holders of our common stock and will increase the number of shares eligible for resale in the public market.

Significant holders or beneficial owners of our common stock may not be permitted to exercise the pre-funded warrants that they hold for common stock.

A holder of the pre-funded warrants will not be entitled to exercise any portion of such pre-funded warrants for common stock if, upon giving effect to such exercise, the holder would beneficially own an aggregate number of shares of our common stock (together with its attribution affiliates) that exceeds 4.99% (or 9.99%) at the initial election of the holder) of the number of shares of our common stock that would be outstanding immediately after giving effect to the exercise, as such percentage ownership is set forth in accordance with the terms of the pre-funded warrants. A holder of pre-funded warrants may elect to increase the maximum ownership percentage under the pre-funded warrants to any other percentage not in excess of 19.99% upon at least 61 days’ prior notice from the holder to us. As a result, you may not be able to exercise your pre-funded warrants for shares of our common stock at a time when it would be financially beneficial for you to do so. In such circumstance you could seek to sell your pre-funded warrants to realize value, but you may be unable to do so in the absence of an established trading market for the warrants.

If we do not maintain a current and effective registration statement relating to the shares of common stock issuable upon exercise of the pre-funded warrants, holders will only be able to exercise such pre-funded warrants on a “cashless basis.”

If we do not maintain a current and effective registration statement relating to the shares of common stock issuable upon exercise of the pre-funded warrants at the time that holders wish to exercise such pre-funded warrants, they will only be able to exercise them on a “cashless basis,” provided that an exemption from registration is available. As a result, the number of shares of common stock that holders will receive upon exercise of the pre-funded warrants will be fewer than it would have been had such holder exercised his, her or its warrant for cash, and holders may be limited in their ability to immediately sell shares upon exercise, subject to volume or other securities law limitations. Further, if an exemption from registration is not available, holders would not be able to exercise on a cashless basis and would only be able to exercise their pre-funded warrants for cash if a current and effective registration statement relating to the shares of common stock issuable upon exercise of the pre-funded warrants is available.

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Holders of the pre-funded warrants will have no rights as common stockholders until they acquire our common stock.

Until you acquire shares of our common stock upon exercise of the pre-funded warrants, you will have no rights with respect to our common stock issuable upon exercise of the pre-funded warrants, including the right to receive dividend payments, vote or respond to tender offers. Upon exercise of your pre-funded warrants, you will be entitled to exercise the rights of a common stockholder only as to matters for which the record date occurs after the exercise date.

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Description of securities we are offering

We are offering shares of our common stock, or for certain investors that so choose, in lieu of shares of common stock, pre-funded warrants to purchase shares of our common stock. The common stock and the pre-funded warrants will be sold at the same time. The shares of common stock and the pre-funded warrants are immediately separable and will be issued separately. The shares of common stock issuable from time to time upon exercise of the pre-funded warrants, if any, are also being offered pursuant to the prospectus supplement and the accompanying prospectus.

Common stock

Our common stock is entitled to one vote for each share held of record on all matters submitted to a vote of the stockholders, including the election of directors, and does not have cumulative voting rights. Accordingly, the holders of a majority of the shares of our common stock entitled to vote in any election of directors can elect all of the directors standing for election.

Subject to preferences that may be applicable to any then-outstanding preferred stock, the holders of common stock are entitled to receive dividends, if any, as may be declared from time to time by our board of directors out of legally available funds.

Pre-funded warrants

The material terms and provisions of the pre-funded warrants being issued in this offering are summarized below. The following description is subject to, and qualified in its entirety by, the form of pre-funded warrant which will be filed as an exhibit to a Current Report on Form 8-K to be filed by us with the U.S. Securities and Exchange Commission (the SEC), in connection with this offering. You should review the form of pre-funded warrant for a complete description of the terms and conditions applicable to the pre-funded warrants.

Exercisability. The pre-funded warrants will be immediately exercisable, at the option of each holder, in whole or in part by delivering to us a duly executed exercise notice and by payment in full in immediately available funds for the number of shares of common stock purchased upon such exercise. The holder may also exercise the pre-funded warrant through a “cashless exercise,” in which case, the holder would receive upon such exercise, the net number of shares of common stock determined according to the formula set forth in the pre-funded warrant. The exercise price must be paid by the holder in cash in immediately available funds.

Exercise limitations. A holder (together with its affiliates and other attribution parties) may not exercise any portion of a pre-funded warrant to the extent that immediately prior to or after giving effect to such exercise the holder would own more than 4.99% (or 9.99%) of our outstanding common stock immediately after exercise, which percentage may be changed at the holder’s election to a higher or lower percentage not in excess of 19.99% (if exceeding such percentage would result in a change of control under Nasdaq Listing Rule 5635(b) or any successor rule), provided that any such increase will require the holder to provide us with at least 61 days’ advance notice.

Exercise price and term. Each pre-funded warrant offered hereby has an initial exercise price per share equal to $0.0001. The pre-funded warrants are immediately exercisable, may be exercised at any time and will not expire until exercised in full. The exercise price and number of shares of common stock issuable upon exercise is subject to adjustment in the event of stock dividends and distributions, stock splits, stock combinations, reclassifications or similar events affecting our common stock.

Transferability. Subject to compliance with any applicable securities laws, the pre-funded warrants are separately tradeable immediately after issuance at the option of the holders and may be transferred at the option of the holders.

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No listing. There is no established public trading market for the pre-funded warrants and we do not expect a market to develop. In addition, we do not intend to apply for listing of the pre-funded warrants on any securities exchange or recognized trading system, including The Nasdaq Global Market. Without an active market, the liquidity of the pre-funded warrants will be limited.

Fundamental transactions. In the event of a fundamental transaction, as described in the pre-funded warrants and generally including any reorganization, recapitalization or reclassification of our common stock, the sale, transfer or other disposition of all or substantially all of our properties or assets, our consolidation or merger with or into another person, the acquisition of more than 50% of our outstanding common stock, or any person or group becoming the beneficial owner of more than 50% of the voting power represented by our outstanding common stock, the pre-funded warrants will be deemed to be fully exercised as of immediately prior to the consummation of such transaction, and the holders thereof will be entitled to receive the kind and amount of securities, cash or other property as holders of common stock in such fundamental transaction.

Rights as a stockholder. Except as otherwise provided in the pre-funded warrants or by virtue of a holder’s ownership of shares of our common stock, the holders of the pre-funded warrants do not have the rights or privileges of holders of our common stock, including the right to vote, until they exercise their pre-funded warrants.

Warrant agent. We will act as warrant agent for the pre-funded warrants.

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Underwriting

The underwriters will purchase the pre-funded warrants pursuant to the underwriting agreement described in the Preliminary Prospectus Supplement on terms generally consistent with those applicable to the shares of common stock being sold in the offering. The per share underwriting discounts and commissions for the pre-funded warrants will be equal to the per share underwriting discounts and commissions on the shares of our common stock sold in the offering.

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Material U.S. federal income tax consequences of our common stock and pre-funded warrants

The following is a summary of certain material U.S. federal income tax consequences of the ownership and disposition of our common stock and pre-funded warrants offered pursuant to the Preliminary Prospectus Supplement and this free writing prospectus. This discussion is not a complete analysis of all potential U.S. federal income tax consequences relating thereto, does not address the potential application of the Medicare contribution tax on net investment income, any alternative minimum tax, or the special tax accounting rules under Section 451(b) of the Internal Revenue Code of 1986, as amended (the Code), and does not address any U.S. federal non-income tax consequences such as estate or gift tax consequences or any tax consequences arising under any state, local, or non-U.S. tax laws. This discussion is based on the Code and applicable Treasury Regulations promulgated thereunder, published rulings and administrative pronouncements of the Internal Revenue Service (the IRS) and judicial decisions, all as in effect as of the date hereof. These authorities are subject to differing interpretations and may change, possibly retroactively, resulting in U.S. federal income tax consequences different from those discussed below. We have not requested a ruling from the IRS with respect to the statements made and the conclusions reached in the following summary, and there can be no assurance that the IRS or a court will agree with such statements and conclusions.

This discussion is limited to holders who purchase our common stock or pre-funded warrants offered by the Preliminary Prospectus Supplement and this free writing prospectus and who hold our common stock or pre-funded warrants as a “capital asset” within the meaning of Section 1221 of the Code (generally, property held for investment). This discussion does not address all of the U.S. federal income tax consequences that may be relevant to a particular holder in light of such holder’s particular circumstances. This discussion also does not consider any specific facts or circumstances that may be relevant to holders subject to special rules under the U.S. federal income tax laws, including:

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If an entity or arrangement that is classified as a partnership for U.S. federal income tax purposes holds our common stock or pre-funded warrants, the U.S. federal income tax treatment of a partner in the partnership will generally depend on the status of the partner, the activities of the partnership and certain determinations made at the partner level. Partnerships holding our common stock or pre-funded warrants and the partners in such partnerships are urged to consult their tax advisors about the particular U.S. federal income tax consequences to them of acquiring, owning and disposing of our common stock or pre-funded warrants.

THIS DISCUSSION IS FOR INFORMATIONAL PURPOSES ONLY AND IS NOT TAX ADVICE. PROSPECTIVE INVESTORS SHOULD CONSULT THEIR TAX ADVISORS REGARDING THE PARTICULAR U.S. FEDERAL INCOME TAX CONSEQUENCES TO THEM OF ACQUIRING, OWNING, AND DISPOSING OF OUR COMMON STOCK OR PRE-FUNDED WARRANTS, AS WELL AS ANY TAX CONSEQUENCES ARISING UNDER ANY STATE, LOCAL, OR NON-U.S. TAX LAWS AND ANY U.S. FEDERAL NON-INCOME TAX LAWS, OR UNDER ANY APPLICABLE INCOME TAX TREATY.

For purposes of this discussion, a “U.S. holder” is any beneficial owner of our common stock or pre-funded warrants that is a “U.S. person” (as defined below) and is not a partnership (including any entity or arrangement treated as a partnership) for U.S. federal income tax purposes. A “U.S. person” is any person that, for U.S. federal income tax purposes, is or is treated as any of the following:

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For purposes of this discussion, a “non-U.S. holder” is a beneficial owner of our common stock or pre-funded warrants that is neither a U.S. person nor a partnership (including any entity or arrangement treated as a partnership) for U.S. federal income tax purposes.

Characterization of the pre-funded warrants for tax purposes

Although the characterization of the pre-funded warrants for U.S. federal income tax purposes is not entirely clear, because the exercise price of the pre-funded warrants is a nominal amount, we expect to treat the pre-funded warrants as stock for U.S. federal income tax purposes. Accordingly, no gain or loss generally should be recognized upon the exercise of a pre-funded warrant (other than with respect to any cash paid in lieu of a fractional share) and, upon exercise, the holding period of a pre-funded warrant generally should carry over to the share received. Similarly, the tax basis of the pre-funded warrant generally should carry over to the share received upon exercise, increased by the exercise price. Except where specifically noted below, the following discussion assumes our pre-funded warrants are treated as our stock. Some portions of the below discussion make reference to potential consequences associated with the acquisition, ownership and disposition of the pre-funded warrants independent of their potential characterization as stock.

Our position with respect to the U.S. federal income tax characterization of pre-funded warrants is not binding on the IRS and the IRS may treat the pre-funded warrants as warrants to acquire our common stock for U.S. federal income tax purposes and, if so, the amount and character of your gain with respect to an investment in our pre-funded warrants could differ from what is described herein. You should consult your tax advisor regarding the characterization of pre-funded warrants for U.S. federal income tax purposes, and the consequences to you of an investment in the pre-funded warrants based on your own particular facts and circumstances.

Tax consequences to U.S. holders

Distributions on our common stock or pre-funded warrants

We have never declared or paid cash dividends on our capital stock, and we do not currently intend to pay any cash dividends on our capital stock in the foreseeable future. However, if we make cash or other property distributions on our common stock or pre-funded warrants, such distributions will constitute dividends for U.S. federal income tax purposes to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. Dividends received by certain non-corporate U.S. holders, including individuals, are generally taxed at long-term capital gains rates, provided certain holding period requirements are satisfied. Dividends received by a corporate U.S. holder may be eligible for a dividends received deduction, subject to applicable limitations.

Amounts that exceed such current and accumulated earnings and profits and, therefore, are not treated as dividends for U.S. federal income tax purposes will constitute a return of capital and will first be applied against and reduce a holder’s tax basis in our common stock or pre-funded warrants, but not below zero. Any amount distributed in excess of basis will be treated as gain realized on the sale or other disposition of our common stock or pre-funded warrants and will be treated as described under the section titled “—Sale or other disposition of our common stock or pre-funded warrants” below.

Constructive dividends on pre-funded warrants

A U.S. holder of a pre-funded warrant may, in some circumstances, be deemed to have received a distribution subject to U.S. federal income tax as a result of an adjustment or the non-occurrence of an adjustment to the exercise price or number of shares of our common stock issuable upon exercise of the pre-funded warrant. U.S. holders should consult their tax advisors regarding the proper treatment of any adjustments (or the non-occurrence of any adjustments) to the pre-funded warrants.

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Sale or other disposition of our common stock or pre-funded warrants

For U.S. federal income tax purposes, gain or loss realized on the sale or other taxable disposition of our common stock or pre-funded warrants will generally be capital gain or loss, and will be long-term capital gain or loss if the U.S. holder has held the common stock or pre-funded warrants for more than one year. The amount of the gain or loss will equal the difference between (i) the amount of cash and the fair market value of any property received on the disposition and (ii) such U.S. holder’s tax basis in the common stock or pre-funded warrants disposed of. Long-term capital gains recognized by non-corporate U.S. holders generally will be subject to reduced U.S. federal income tax rates. The deductibility of capital losses is subject to limitations.

Information reporting and backup withholding

Information reporting requirements generally will apply to distributions (including deemed distributions) on our common stock or pre-funded warrants, and gross proceeds on the sale or other disposition of our common stock and pre-funded warrants, unless the U.S. holder is an exempt recipient (such as certain corporations). Backup withholding (currently at a 24% rate) will apply to those payments if the U.S. holder is not otherwise exempt and fails to provide its correct taxpayer identification number or certification of exempt status on an IRS Form W-9 (Request for Taxpayer Identification Number and Certification), or if the U.S. holder is notified by the IRS that it has failed to report in full payments of interest and dividend income. Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules will be allowed as a refund or a credit against a U.S. holder’s U.S. federal income tax liability provided the required information is furnished timely to the IRS.

If backup withholding is applied to you, you should consult with your own tax advisor to determine whether you have overpaid your U.S. federal income tax, and whether you are able to obtain a tax refund or credit of the overpaid amount.

Tax consequences to non-U.S. holders

Distributions on our common stock or pre-funded warrants

As discussed above under “—Tax consequences to U.S. holders—Distributions on our common stock or pre-funded warrants,” we have never declared or paid cash dividends on our capital stock, and we do not currently intend to pay any cash dividends on our capital stock in the foreseeable future. However, if we make cash or other property distributions on our common stock or pre-funded warrants, such distributions will constitute dividends for U.S. federal income tax purposes to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles.

Amounts not treated as dividends for U.S. federal income tax purposes will constitute a return of capital and first be applied against and reduce a non-U.S. holder’s adjusted tax basis in our common stock or pre-funded warrants, but not below zero. Any excess will be treated as capital gain and will be treated as described below under “—Gain on disposition of our common stock or pre-funded warrants.”

Subject to the discussions below regarding effectively connected income, backup withholding, and Sections 1471 through 1474 of the Code (FATCA), dividends paid to a non-U.S. holder of our common stock or pre-funded warrants generally will be subject to U.S. federal withholding tax at a rate of 30% of the gross amount of the dividends or such lower rate specified by an applicable income tax treaty. To receive the benefit of a reduced treaty rate, a non-U.S. holder must furnish us or the applicable withholding agent with a valid IRS Form W-8BEN or IRS Form W-8BEN-E, as applicable (or other appropriate form, or applicable successor form), certifying such holder’s qualification for the reduced rate. This certification must be provided to us or the applicable withholding agent before the payment of dividends and may need to be updated periodically. In the case of a non-U.S. holder that is an entity, Treasury Regulations and the relevant tax treaty provide rules to determine whether, for purposes of determining the applicability of the tax treaty, dividends will be treated as paid to the entity or to those

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holding an interest in the entity. If the non-U.S. holder holds the common stock or pre-funded warrants through a financial institution or other agent acting on the non-U.S. holder’s behalf, the non-U.S. holder will be required to provide appropriate documentation to the agent, which then will be required to provide certification to us or the applicable withholding agent, either directly or through other intermediaries. Non-U.S. holders that do not provide the required certification on a timely basis, but that qualify for a reduced treaty rate, may obtain a refund of any excess amounts withheld by timely filing an appropriate claim for refund with the IRS.

If a non-U.S. holder holds our common stock or pre-funded warrants in connection with the conduct of a trade or business in the United States, and dividends paid on our common stock or pre-funded warrants are effectively connected with such holder’s U.S. trade or business (and, if required by an applicable tax treaty, are attributable to such holder’s permanent establishment or fixed base in the United States), the non-U.S. holder will generally be exempt from U.S. federal withholding tax. To claim the exemption, the non-U.S. holder must generally furnish a valid IRS Form W-8ECI (or applicable successor form) to the applicable withholding agent. This certification must be provided to us or the applicable withholding agent before the payment of dividends and may need to be updated periodically.

Although not subject to withholding tax, any such effectively connected dividends paid on our common stock or pre-funded warrants generally will be subject to U.S. federal income tax as if such holder were a resident of the United States at the regular U.S. federal income tax rates applicable to United States residents. A non-U.S. holder that is a foreign corporation also may be subject to an additional branch profits tax equal to 30% (or such lower rate specified by an applicable income tax treaty) of its effectively connected earnings and profits for the taxable year, as adjusted for certain items. Non-U.S. holders should consult their tax advisors regarding any applicable income tax treaties that may provide for different rules.

Constructive dividends on pre-funded warrants

A non-U.S. holder of pre-funded warrants may, in some circumstances, be deemed to have received a distribution subject to U.S. federal income tax as a result of an adjustment or the non-occurrence of an adjustment to the exercise price or number of shares of our common stock issuable upon exercise of the pre-funded warrant. Any resulting withholding tax attributable to deemed dividends may be collected from other amounts payable or distributable to the non-U.S. holder. Non-U.S. holders should consult their tax advisors regarding the proper treatment of any adjustments (or the non-occurrence of any adjustments) to the pre-funded warrants.

Gain on disposition of our common stock or pre-funded warrants

Subject to the discussions below regarding backup withholding and FATCA, a non-U.S. holder generally will not be subject to U.S. federal income tax on any gain realized on the sale or other taxable disposition of our common stock or pre-funded warrants, unless:

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Determining whether we are a USRPHC depends on the fair market value of our USRPIs relative to the fair market value of our other trade or business assets and our foreign real property interests. We do not believe that we are, or have been, and do not anticipate becoming a USRPHC for U.S. federal income tax purposes, although there can be no assurance we will not in the future become a USRPHC.

Gain described in the first bullet point above generally will be subject to U.S. federal income tax as if such holder were a resident of the United States at the regular U.S. federal income tax rates applicable to United States residents. A non-U.S. holder that is a foreign corporation also may be subject to an additional branch profits tax equal to 30% (or such lower rate specified by an applicable income tax treaty) of its effectively connected earnings and profits for the taxable year, as adjusted for certain items. A non-U.S. holder described in the second bullet point above will be subject to U.S. federal income tax at a flat 30% rate (unless an applicable income tax treaty provides for different treatment) on gain realized upon the sale or other taxable disposition of our common stock or pre-funded warrants, but such gain may be offset by certain U.S.-source capital losses (even though the individual is not considered a resident of the United States), provided that the non-U.S. holder has timely filed U.S. federal income tax returns with respect to such losses. Non-U.S. holders should consult their tax advisors regarding any applicable income tax treaties that may provide for different rules.

Information reporting and backup withholding

Annual reports are required to be filed with the IRS and provided to each non-U.S. holder indicating the amount of distributions (including deemed distributions) on our common stock or pre-funded warrants paid to such holder and the amount of any tax withheld with respect to those distributions. These information reporting requirements apply even if no withholding was required (because the distributions were effectively connected with the holder’s conduct of a U.S. trade or business, or withholding was reduced or eliminated by an applicable income tax treaty) and regardless of whether such distributions constitute dividends. This information also may be made available under a specific treaty or agreement with the tax authorities in the country in which the non-U.S. holder resides or is established. Backup withholding, currently at a 24% rate, generally will not apply to payments to a non-U.S. holder of dividends on or the gross proceeds of a disposition of our common stock or pre-funded warrants provided the non-U.S. holder furnishes the required certification for its non-U.S. status, such as by providing a valid IRS Form W-8BEN, IRS Form W-8BEN-E, or IRS Form W-8ECI, as applicable, or certain other requirements are met. Backup withholding may apply if the payor has actual knowledge, or reason to know, that the holder is a U.S. person who is not an exempt recipient.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules may be allowed as a refund or a credit against a non-U.S. holder’s U.S. federal income tax liability, provided the required information is timely furnished to the IRS. If any amount is withheld under the backup withholding rules, the non-U.S. holder should consult with a U.S. tax advisor regarding the possibility of and procedure for obtaining a refund or a credit against the non-U.S. holder’s U.S. federal income tax liability, if any.

Withholding on foreign entities

FATCA imposes a U.S. federal withholding tax of 30% on certain payments made to a “foreign financial institution” (as specially defined under these rules) unless such institution enters into an agreement with the U.S. government to withhold on certain payments and to collect and provide to the U.S. tax authorities substantial information regarding certain U.S. account holders of such institution (which includes certain equity and debt holders of such institution, as well as certain account holders that are foreign entities with U.S. owners) or an exemption applies. FATCA also generally will impose a U.S. federal withholding tax of 30% on certain payments made to a non-financial foreign entity unless such entity provides the withholding agent a certification identifying certain direct and indirect U.S. owners of the entity or an

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exemption applies. An intergovernmental agreement between the United States and an applicable foreign country may modify these requirements. Under certain circumstances, a non-U.S. holder might be eligible for refunds or credits of such taxes. FATCA applies to dividends (including deemed dividends) paid on our common stock or pre-funded warrants and, subject to the proposed Treasury Regulations described below, also applies to gross proceeds from sales or other dispositions of our common stock or pre-funded warrants. The U.S. Treasury Department has released proposed Treasury Regulations which, if finalized in their present form, would eliminate the federal withholding tax of 30% applicable to the gross proceeds of a disposition of our common stock or pre-funded warrants. In its preamble to such proposed Treasury Regulations, the U.S. Treasury Department stated that taxpayers (including applicable withholding agents) may generally rely on the proposed Treasury Regulations until final regulations are issued.

Prospective investors are encouraged to consult with their own tax advisors regarding the possible implications of FATCA on their investment in our common stock or pre-funded warrants.

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General

Additional conforming changes are hereby made to the Preliminary Prospectus Supplement to reflect the changes described in this free writing prospectus. All terms of the Preliminary Prospectus Supplement applicable to our shares of common stock will be applicable to the shares of common stock underlying the pre-funded warrants upon issuance.

Beta Bionics, Inc. has filed a registration statement (including a preliminary prospectus supplement, dated September 15, 2026 and the accompanying prospectus) with the SEC for the offering to which this communication relates. A preliminary prospectus supplement dated September 15, 2026 related to the offering has been filed with the SEC and is available on the SEC’s website located at http://www.sec.gov. Copies of the preliminary prospectus supplement and the accompanying prospectus related to this offering, when available, may be obtained from J.P. Morgan Securities LLC, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, New York 11717, or by email at [email protected] and [email protected]; or from Piper Sandler & Co., 350 North 5th Street, Suite 1000, Minneapolis, Minnesota 55401, Attention: Prospectus Department, by telephone at (800) 747-3924, or by email at [email protected]; or from Wells Fargo Securities, LLC, Attention: Wells Fargo Securities, 90 South 7th Street, 5th Floor, Minneapolis, Minnesota 55402, by telephone at 800-645-3751 (option #5), by email at [email protected]; or from Leerink Partners LLC, Attention: Syndicate Department, 53 State Street, 40th Floor, Boston, Massachusetts 02109, by telephone at (800) 808-7525, ext. 6105, or by email at [email protected].

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