MIAMI INTERNATIONAL HOLDINGS, INC.

The following table summarizes our cash and cash equivalents and capitalization as of June 30, 2025:

•on an actual basis;

•on a pro forma basis, to give effect to (i) the conversion of all outstanding shares of Series B preferred stock into an aggregate of 793,427 shares of our common stock in connection with the completion of this offering; (ii) the conversion of all outstanding shares of our nonvoting common stock into an aggregate of 3,731,573 shares of common stock in connection with the completion of this offering; (iii) the extinguishment of the liability associated with outstanding puttable common stock upon the completion of the offering; (iv) the extinguishment of the liability associated with the puttable warrants issued in connection with the 2029 Senior Secured Term Loan; and

•on a pro forma as adjusted basis, to reflect (i) the pro forma items described immediately above, (ii) the sale and issuance by us of shares of common stock in this offering at an assumed initial public offering price of $ per share, which is the midpoint of the price range set forth on the cover page of this prospectus, after deducting estimated underwriting discounts and commission and estimated offering expenses payable by us, (iii) the repayment of the 2029 Senior Secured Loan with a portion of the proceeds of this offering, and (iv) the IPO RSA Vest, including our payment of approximately $ million in satisfaction of tax withholding and remittance obligations and the surrender of up to shares of common stock in connection with the IPO RSA Vest.

You should read the information in this table together with our consolidated financial statements and related notes to those statements included elsewhere in this prospectus, as well as the information set forth under the headings “Use of Proceeds,” “Prospectus Summary — Summary Consolidated Financial Data,” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations.” The pro forma and pro forma as adjusted information below is illustrative only and our capitalization following the closing of this offering will be adjusted based on the actual initial public offering price and other terms of the offering determined at pricing (in thousands, except share and per share amounts):

(1)Each $1.00 increase (decrease) in the assumed initial price to the public of $ per share, which is the midpoint of the price range set forth on the cover page of this prospectus, would increase (decrease) each of cash and cash equivalents, additional paid-in capital, total stockholders’ equity (deficit) and total capitalization on a pro forma as adjusted basis by approximately $ million, assuming that the number of shares offered by us, as set forth on the cover page of this prospectus, remains the same, and after deducting estimated underwriting discounts and commissions and estimated offering expenses. We may also increase or decrease the number of shares we are offering. Each increase (decrease) of 1,000,000 shares in the number of shares offered by us would increase (decrease) each of cash and cash equivalents, additional paid-in capital, total stockholders’ equity (deficit) and total capitalization on a pro forma as adjusted basis by approximately $ million, assuming that the assumed initial price to the public remains the same, and after deducting the estimated underwriting discounts and commissions and estimated offering expenses. The pro forma as adjusted information discussed above is illustrative only and will adjust based on the actual initial price to the public and other terms of this offering determined at pricing.

Pursuant to the Company’s Amended and Restated Certificate of Incorporation, each share of nonvoting common stock is convertible into one share of common stock at the option of the holder thereof and each share of Series B preferred stock is convertible into one share of common stock at the option of the holder thereof upon the occurrence of certain events, including the completion of this offering. The Company expects to have obtained optional conversion notices requesting conversion of all outstanding shares of nonvoting common stock and Series B preferred stock effective upon the completion of this offering from all holders of such shares in advance of the completion of this offering.

The number of shares of our common stock issued and outstanding, pro forma and pro forma as adjusted, in the table above is based on shares of common stock outstanding (after giving effect to the conversion of all of our shares of Series B preferred stock and nonvoting common stock outstanding as of June 30, 2025 into an aggregate of 4,525,000 shares of our common stock in connection with the completion of this offering), and excludes as of June 30, 2025:

•925,395 shares of Series B preferred stock issuable upon the exercise of Series B preferred stock options outstanding as of June 30, 2025, at a weighted average exercise price of $12.00 per share, which stock options will be converted into options to purchase common stock in connection with the completion of this offering;

•14,355,665 shares of nonvoting common stock issuable upon the exercise of nonvoting common stock options outstanding as of June 30, 2025, at a weighted average exercise price of $13.89 per share, which stock options will be converted into options to purchase common stock in connection with the completion of this offering;

•322,840 shares of common stock issuable upon the conversion of convertible promissory notes and accrued and unpaid interest thereon outstanding as of June 30, 2025, at a weighted average conversion price of $16.04 per share; and

•8,250,880 additional shares of common stock reserved for future issuance under our 2022 Equity Incentive Plan, as well as any increases in the number of shares of our common stock reserved for future issuance under our 2022 Equity Incentive Plan.