CDNL · Cardinal Infrastructure Group Inc.

These shares represent restricted stock units ("RSUs") granted on June 5, 2026. The RSUs vest on the earlier to occur of (1) the next annual meeting of the Company's stockholders following the date of grant (so long as such next annual meeting is at least 50 weeks after the immediately preceding year's annual meeting of stockholders) and (2) the one-year anniversary of the date of grant, provided that, in each case, the Reporting Person continues to serve as a director of the Company through such date.

These shares represent restricted stock units ("RSUs") granted on June 5, 2026. The RSUs vest on the earlier to occur of (1) the next annual meeting of the Company's stockholders following the date of grant (so long as such next annual meeting is at least 50 weeks after the immediately preceding year's annual meeting of stockholders) and (2) the one-year anniversary of the date of grant, provided that, in each case, the Reporting Person continues to serve as a director of the Company through such date.

The Form 4 filed by the Reporting Person on May 11, 2026 incorrectly reported the Amount of Securities Beneficially Owned following Reported Transaction in Column 5 of Table I. The correct number should have been 32,313.

These shares represent restricted stock units ("RSUs") granted on June 5, 2026. The RSUs vest on the earlier to occur of (1) the next annual meeting of the Company's stockholders following the date of grant (so long as such next annual meeting is at least 50 weeks after the immediately preceding year's annual meeting of stockholders) and (2) the one-year anniversary of the date of grant, provided that, in each case, the Reporting Person continues to serve as a director of the Company through such date.

The Form 4 filed by the Reporting Person on May 11, 2026 incorrectly reported the Amount of Securities Beneficially Owned following Reported Transaction in Column 5 of Table I. The correct number should have been 9,588.

These shares represent restricted stock units ("RSUs") granted on June 5, 2026. The RSUs vest on the earlier to occur of (1) the next annual meeting of the Company's stockholders following the date of grant (so long as such next annual meeting is at least 50 weeks after the immediately preceding year's annual meeting of stockholders) and (2) the one-year anniversary of the date of grant, provided that, in each case, the Reporting Person continues to serve as a director of the Company through such date.

The price reported in Column 4 is a weighted average price. The shares were purchased in multiple transactions at prices ranging from $49.32 to $50.31, inclusive. The reporting person hereby undertakes to provide to Cardinal Infrastructure Group Inc., any security holder of Cardinal Infrastructure Group Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in footnote (1) of this Form 4.

The price reported in Column 4 is a weighted average price. The shares were purchased in multiple transactions at prices ranging from $53.31 to $54.30, inclusive. The reporting person hereby undertakes to provide to Cardinal Infrastructure Group Inc., any security holder of Cardinal Infrastructure Group Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in footnote (4) of this Form 4.

The price reported in Column 4 is a weighted average price. The shares were purchased in multiple transactions at prices ranging from $50.36 to $51.35, inclusive. The reporting person hereby undertakes to provide to Cardinal Infrastructure Group Inc., any security holder of Cardinal Infrastructure Group Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in footnote (2) of this Form 4.

The price reported in Column 4 is a weighted average price. The shares were purchased in multiple transactions at prices ranging from $51.42 to $52.37, inclusive. The reporting person hereby undertakes to provide to Cardinal Infrastructure Group Inc., any security holder of Cardinal Infrastructure Group Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in footnote (3) of this Form 4.

These shares represent restricted stock units ("RSUs") granted on May 7, 2026. The RSUs vest as follows, subject to the Reporting Person's continued service through each applicable vesting date: (i) 775 RSUs vested immediately upon execution of the award agreement; (ii) 775 RSUs will vest on June 30, 2026; (iii) 775 RSUs will vest on September 30, 2026; and (iv) 776 RSUs will vest on December 31, 2026.

These shares represent restricted stock units ("RSUs") granted on May 7, 2026. The RSUs vest as follows, subject to the Reporting Person's continued service through each applicable vesting date: (i) 775 RSUs vested immediately upon execution of the award agreement; (ii) 775 RSUs will vest on June 30, 2026; (iii) 775 RSUs will vest on September 30, 2026; and (iv) 776 RSUs will vest on December 31, 2026.

These shares represent restricted stock units ("RSUs") granted on May 7, 2026. The RSUs vest as follows, subject to the Reporting Person's continued service through each applicable vesting date: (i) 775 RSUs vested immediately upon execution of the award agreement; (ii) 775 RSUs will vest on June 30, 2026; (iii) 775 RSUs will vest on September 30, 2026; and (iv) 776 RSUs will vest on December 31, 2026.

These shares represent restricted stock units ("RSUs") granted on May 7, 2026. The RSUs vest as follows, subject to the Reporting Person's continued service through each applicable vesting date: (i) 775 RSUs vested immediately upon execution of the award agreement; (ii) 775 RSUs will vest on June 30, 2026; (iii) 775 RSUs will vest on September 30, 2026; and (iv) 776 RSUs will vest on December 31, 2026.

The price reported in Column 4 is a weighted average price. The shares were purchased in multiple transactions at prices ranging from $36.09 to $36.47, inclusive. The reporting person hereby undertakes to provide to Cardinal Infrastructure Group Inc., any security holder of Cardinal Infrastructure Group Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in footnote (1) of this Form 4.

Reflects the cancellation for no consideration of Class B Common Stock in connection with the redemption of the membership units of Cardinal Civil Contracting Holdings LLC (the "LLC Units").

The LLC Units may be redeemed by the Reporting Person at any time at the option of the holder for shares of Class A Common Stock on a 1-to-1 basis, and a corresponding number of shares of Class B Common Stock will be forfeited in connection with the redemption. The LLC Units have no expiration date.

The shares of Common Stock reported on this Form 4 are subject to a lock-up agreement, effective as of 12/9/2025 (the "Lock-up Date"), between the Reporting Person and Stifel, Nicolaus & Company, Incorporated and William Blair & Company, L.L.C, pursuant to which shares of Common Stock reported herein cannot be sold for 180 days following the Lock-up Date.

Reflects the cancellation for no consideration of Class B Common Stock in connection with the redemption of the membership units of Cardinal Civil Contracting Holdings LLC (the "LLC Units").

Reflects the cancellation for no consideration of Class B Common Stock in connection with the redemption of the membership units of Cardinal Civil Contracting Holdings LLC (the "LLC Units").

The Reporting Person is the spouse of the trustee of The Rowe Family Irrevocable Trust dated March 13, 2024 ("Rowe Trust"), and as a result, may be deemed to share beneficial ownership of the securities held of record by Rowe Trust.

The LLC Units may be redeemed by the Reporting Person at any time at the option of the holder for shares of Class A Common Stock on a 1-to-1 basis, and a corresponding number of shares of Class B Common Stock will be forfeited in connection with the redemption. The LLC Units have no expiration date.

The Reporting Person is the spouse of the trustee of Spivey Family 2024 Irrevocable Trust U/A dated 5/13/24, as amended ("Spivey Trust"), and as a result, may be deemed to share beneficial ownership of the securities held of record by Spivey Trust.

The LLC Units may be redeemed by the Reporting Person at any time at the option of the holder for shares of Class A Common Stock on a 1-to-1 basis, and a corresponding number of shares of Class B Common Stock will be forfeited in connection with the redemption. The LLC Units have no expiration date.

The shares of Common Stock reported on this Form 4 are subject to a lock-up agreement, effective as of 12/9/2025 (the "Lock-up Date"), between the Reporting Person and Stifel, Nicolaus & Company, Incorporated and William Blair & Company, L.L.C, pursuant to which shares of Common Stock reported herein cannot be sold for 180 days following the Lock-up Date.

The LLC Units may be redeemed by the Reporting Person at any time at the option of the holder for shares of Class A Common Stock on a 1-to-1 basis, and a corresponding number of shares of Class B Common Stock will be forfeited in connection with the redemption. The LLC Units have no expiration date.

The shares of Common Stock reported on this Form 4 are subject to a lock-up agreement, effective as of 12/9/2025 (the "Lock-up Date"), between the Reporting Person and Stifel, Nicolaus & Company, Incorporated and William Blair & Company, L.L.C, pursuant to which shares of Common Stock reported herein cannot be sold for 180 days following the Lock-up Date.

The shares of Common Stock reported on this Form 4 are subject to a lock-up agreement, effective as of 12/9/2025 (the "Lock-up Date"), between the Reporting Person and Stifel, Nicolaus & Company, Incorporated and William Blair & Company, L.L.C, pursuant to which shares of Common Stock reported herein cannot be sold for 180 days following the Lock-up Date.

The LLC Units may be redeemed by the Reporting Person at any time at the option of the holder for shares of Class A Common Stock on a 1-to-1 basis, and a corresponding number of shares of Class B Common Stock will be forfeited in connection with the redemption. The LLC Units have no expiration date.

The Reporting Person is the spouse of the trustee of The Rowe Family Irrevocable Trust dated March 13, 2024 ("Rowe Trust"), and as a result, may be deemed to share beneficial ownership of the securities held of record by Rowe Trust.

The LLC Units may be redeemed by the Reporting Person at any time at the option of the holder for shares of Class A Common Stock on a 1-to-1 basis, and a corresponding number of shares of Class B Common Stock will be forfeited in connection with the redemption. The LLC Units have no expiration date.

The Reporting Person is the spouse of the trustee of West Family 2024 Irrevocable Trust U/A dated 3/20/24, as amended ("West Trust"), and as a result, may be deemed to share beneficial ownership of the securities held of record by West Trust.

Reflects the cancellation for no consideration of Class B Common Stock in connection with the redemption of the membership units of Cardinal Civil Contracting Holdings LLC (the "LLC Units").

The Reporting Person is the spouse of the trustee of West Family 2024 Irrevocable Trust U/A dated 3/20/24, as amended ("West Trust"), and as a result, may be deemed to share beneficial ownership of the securities held of record by West Trust.

Reflects the cancellation for no consideration of Class B Common Stock in connection with the redemption of the membership units of Cardinal Civil Contracting Holdings LLC (the "LLC Units").

The Reporting Person is the spouse of the trustee of Spivey Family 2024 Irrevocable Trust U/A dated 5/13/24, as amended ("Spivey Trust"), and as a result, may be deemed to share beneficial ownership of the securities held of record by Spivey Trust.

Reflects the cancellation for no consideration of Class B Common Stock in connection with the redemption of the membership units of Cardinal Civil Contracting Holdings LLC (the "LLC Units").

Represents securities received as part of the Issuer's reorganization in connection with its initial public offering, as described in the registration statement on Form S-1 relating to the initial public offering. These securities were previously reported on a Form 3 filed by the Reporting Person.

The Reporting Person is the spouse of the trustee of The Rowe Family Irrevocable Trust dated March 13, 2024 ("Rowe Trust"), and as a result, may be deemed to share beneficial ownership of the securities held of record by Rowe Trust.

The LLC Units may be redeemed by the Reporting Person at any time at the option of the holder for shares of Class A Common Stock on a 1-to-1 basis, and a corresponding number of shares of Class B Common Stock will be forfeited in connection with the redemption. The LLC Units have no expiration date.

Represents securities received as part of the Issuer's reorganization in connection with its initial public offering, as described in the registration statement on Form S-1 relating to the initial public offering. These securities were previously reported on a Form 3 filed by the Reporting Person.

The Reporting Person is the spouse of the trustee of The Rowe Family Irrevocable Trust dated March 13, 2024 ("Rowe Trust"), and as a result, may be deemed to share beneficial ownership of the securities held of record by Rowe Trust.

The LLC Units may be redeemed by the Reporting Person at any time at the option of the holder for shares of Class A Common Stock on a 1-to-1 basis, and a corresponding number of shares of Class B Common Stock will be forfeited in connection with the redemption. The LLC Units have no expiration date.

Represents securities received as part of the Issuer's reorganization in connection with its initial public offering, as described in the registration statement on Form S-1 relating to the initial public offering. These securities were previously reported on a Form 3 filed by the Reporting Person.

The LLC Units may be redeemed by the Reporting Person at any time at the option of the holder for shares of Class A Common Stock on a 1-to-1 basis, and a corresponding number of shares of Class B Common Stock will be forfeited in connection with the redemption. The LLC Units have no expiration date.

Represents securities received as part of the Issuer's reorganization in connection with its initial public offering, as described in the registration statement on Form S-1 relating to the initial public offering. These securities were previously reported on a Form 3 filed by the Reporting Person.

Represents securities received as part of the Issuer's reorganization in connection with its initial public offering, as described in the registration statement on Form S-1 relating to the initial public offering. These securities were previously reported on a Form 3 filed by the Reporting Person.

The Reporting Person is the spouse of the trustee of Spivey Family 2024 Irrevocable Trust U/A dated 5/13/24, as amended ("Spivey Trust"), and as a result, may be deemed to share beneficial ownership of the securities held of record by Spivey Trust.

The LLC Units may be redeemed by the Reporting Person at any time at the option of the holder for shares of Class A Common Stock on a 1-to-1 basis, and a corresponding number of shares of Class B Common Stock will be forfeited in connection with the redemption. The LLC Units have no expiration date.

Represents securities received as part of the Issuer's reorganization in connection with its initial public offering, as described in the registration statement on Form S-1 relating to the initial public offering. These securities were previously reported on a Form 3 filed by the Reporting Person[s].

Represents securities received as part of the Issuer's reorganization in connection with its initial public offering, as described in the registration statement on Form S-1 relating to the initial public offering. These securities were previously reported on a Form 3 filed by the Reporting Person[s].

Represents securities received as part of the Issuer's reorganization in connection with its initial public offering, as described in the registration statement on Form S-1 relating to the initial public offering. These securities were previously reported on a Form 3 filed by the Reporting Person[s].

The Reporting Person is the spouse of the trustee of West Family 2024 Irrevocable Trust U/A dated 3/20/24, as amended ("West Trust"), and as a result, may be deemed to share beneficial ownership of the securities held of record by West Trust.

Represents securities received as part of the Issuer's reorganization in connection with its initial public offering, as described in the registration statement on Form S-1 relating to the initial public offering. These securities were previously reported on a Form 3 filed by the Reporting Person.

Represents securities received as part of the Issuer's reorganization in connection with its initial public offering, as described in the registration statement on Form S-1 relating to the initial public offering. These securities were previously reported on a Form 3 filed by the Reporting Person.

The LLC Units may be redeemed by the Reporting Person at any time at the option of the holder for shares of Class A Common Stock on a 1-to-1 basis, and a corresponding number of shares of Class B Common Stock will be forfeited in connection with the redemption. The LLC Units have no expiration date.

Represents securities received as part of the Issuer's reorganization in connection with its initial public offering, as described in the registration statement on Form S-1 relating to the initial public offering. These securities were previously reported on a Form 3 filed by the Reporting Person[s].

The Reporting Person is the spouse of the trustee of West Family 2024 Irrevocable Trust U/A dated 3/20/24, as amended ("West Trust"), and as a result, may be deemed to share beneficial ownership of the securities held of record by West Trust.

The LLC Units may be redeemed by the Reporting Person at any time at the option of the holder for shares of Class A Common Stock on a 1-to-1 basis, and a corresponding number of shares of Class B Common Stock will be forfeited in connection with the redemption. The LLC Units have no expiration date.

Represents securities received as part of the Issuer's reorganization in connection with its initial public offering, as described in the registration statement on Form S-1 relating to the initial public offering. These securities were previously reported on a Form 3 filed by the Reporting Person.

The Reporting Person is the spouse of the trustee of Spivey Family 2024 Irrevocable Trust U/A dated 5/13/24, as amended ("Spivey Trust"), and as a result, may be deemed to share beneficial ownership of the securities held of record by Spivey Trust.