6,666,667 shares Common stock This is the initial public offering of shares of common stock of Ategrity Specialty Insurance CompanyHoldings. We are offering 6,666,667 shares of common stock in this offering. Prior to this offering, there has been no public market for our common stock. The initial public offering priceof our common stock is $17.00 per share. Our common stock has been approved for listing on the New YorkStock Exchange (the “NYSE”) under the symbol “ASIC.” We are an “emerging growth company” as that term is defined in the Jumpstart Our Business Startups Act of2012, and, as such, have elected to comply with certain reduced public company reporting requirements forthis registration statement and may do so in future filings. See “Prospectus summary—Implications of beingan emerging growth company.” Upon completion of this offering, Zimmer Financial Services Group LLC (“ZFSG”) will continue to own morethan a majority of the voting power of our shares of common stock eligible to vote in the election of ourdirectors. As a result, we will be a “controlled company” as defined under the corporate governance rules ofNYSE and will be exempt from certain corporate governance requirements of such rules. See “Management—Director independence and controlled company exemption.” Investing in our common stock involves risks. See “Risk factors” beginning on page19to read aboutfactors you should consider before purchasing shares of our common stock. Neither the Securities and Exchange Commission (“SEC”) nor any state securities commission orregulatory authority has approved or disapproved of these securities or determined if thisprospectus is truthful or complete. Any representation to the contrary is a criminal offense. At our request, the underwriters have reserved for sale, at the initial public offering price, up to 7% of theshares offered by this prospectus, excluding the additional shares that the underwriters have an option topurchase, for sale to certain of our employees, certain of our directors and certain other parties. See“Underwriting—Directed Share Program.” We have granted the underwriters an option for a period of 30 days from the date of this prospectus topurchase up to an additional 1,000,000 shares of our common stock from us at the initial public offeringprice less the underwriting discounts and commissions to cover over-allotments. The underwriters expect to deliver the shares of common stock through the book-entry facilities of theDepository Trust Company on or about June 12, 2025. J.P. MorganCitigroup Barclays June 10, 2025 Table of contents PageAbout this prospectusiProspectus summary1Risk factors19Forward-looking statements59Use of proceeds61Dividend policy62Capitalization63Dilution65Management’s discussion and analysis of financial condition and results of operations67Business96Regulation111Management122Executive and director compensation127Certain relationships and related party transactions136Principal stockholders148Description of capital stock150Shares eligible for future sale157Material U.S. federal income tax considerations to non-U.S. holders160Underwriting164Legal matters174Where you can find more information175Index to financial statementsF-1 About this prospectus Market and industry data In this prospectus, we present certain market and industry data. This information is based onthird-party sources which we believe to be reliable. We have not independently verified any third-party information. Forecasts and projections are based on historical market data, other publiclyavailable information, our knowledge of our industry, and assumptions based on such informationand knowledge. These forecasts and projections have not been verified by any independentsource. In addition, assumptions and estimates of our and our industry’s future performance arenecessarily subject to a high degree of uncertainty and risk due to a variety of factors, includingthose described in “Risk factors.” These and other factors could cause future performance todiffer materially from our assumptions and estimates. See “Forward-looking statements.” Trademarks and service marks Trade names, trademarks, and service marks of other companies appearing in this prospectusare the property of their respective holders. Solely for convenience, the trademarks, servicemarks, and trade names are referred to in this prospectus without theandsymbols, but suchreferences are not intended to indicate, in any way, that the owner thereof will not assert, to thefullest extent under applicable law, such owner’s rights to their trademarks, service marks, andtrade names.SM® Non-GAAP financial measures This prospectus contains certain financial measures that are not presented in accordance withgenerally accepted accounting principles in the United States (“GAAP”). Under U.S. securitieslaws, these measures are called “non-GAAP financial measures.” We believe that certain non-GAAP financial measures provide investors




