STRL · Sterling Infrastructure, Inc.

These shares were retained by the Company at the election of the Reporting Person pursuant to a procedure approved by the Compensation Committee of the Board of Directors to satisfy the Company's tax withholding requirements (based on the closing price of the Company's common stock on the release date) arising from the release of restrictions as permitted by the plan pursuant to which the restricted stock unit award was made.

Of these shares, 21,333 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

These shares were retained by the Company at the election of the Reporting Person pursuant to a procedure approved by the Compensation Committee of the Board of Directors to satisfy the Company's tax withholding requirements (based on the closing price of the Company's common stock on the release date) arising from the release of restrictions as permitted by the plan pursuant to which the restricted stock unit award was made.

Of these shares, 4,735 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

Of these shares, 1,505 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

Reflects a gift of common stock to a charitable donor-advised fund.

Represents the grant of time-vested restricted stock units that will vest on December 31, 2027, provided the service conditions are satisfied.

Of these shares, 60,754 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

These shares were awarded to the Reporting Person by the Company pursuant to the Company's standard director compensation arrangements for non-employee directors.

These shares were awarded to the Reporting Person by the Company pursuant to the Company's standard director compensation arrangements for non-employee directors.

These shares were awarded to the Reporting Person by the Company pursuant to the Company's standard director compensation arrangements for non-employee directors.

These shares were awarded to the Reporting Person by the Company pursuant to the Company's standard director compensation arrangements for non-employee directors.

These shares were awarded to the Reporting Person by the Company pursuant to the Company's standard director compensation arrangements for non-employee directors.

These shares were awarded to the Reporting Person by the Company pursuant to the Company's standard director compensation arrangements for non-employee directors.

These shares were awarded to the Reporting Person by the Company pursuant to the Company's standard director compensation arrangements for non-employee directors.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on December 8, 2025.

Transaction executed in multiple trades at prices ranging from $495.00 to $501.68 per share, inclusive. The price reported in column 4 above reflects the average sale price per share. The Reporting Person hereby undertakes to provide the SEC staff, the Issuer or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote.

Of these shares, 20,754 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on December 8, 2025.

Transaction executed in multiple trades at prices ranging from $450.00 to $458.15 per share, inclusive. The price reported in column 4 above reflects the average sale price per share. The Reporting Person hereby undertakes to provide the SEC staff, the Issuer or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote.

Of these shares, 20,754 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 21, 2025.

Transaction executed in multiple trades at prices ranging from $401.30 to $410.43 per share, inclusive. The price reported in column 4 above reflects the average sale price per share. The Reporting Person hereby undertakes to provide the SEC staff, the Issuer or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote.

Of these shares, 751 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on December 8, 2025.

Transaction executed in multiple trades at prices ranging from $410.20 to $421.40 per share, inclusive. The price reported in column 4 above reflects the average sale price per share. The Reporting Person hereby undertakes to provide the SEC staff, the Issuer or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote.

Of these shares, 20,754 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on December 2, 2025.

Transaction executed in multiple trades at prices ranging from $381.00 to $387.21 per share, inclusive. The price reported in column 4 above reflects the average sale price per share. The Reporting Person hereby undertakes to provide the SEC staff, the Issuer or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote.

Of these shares, 751 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on December 8, 2025.

Transaction executed in multiple trades at prices ranging from $400.00 to $411.38 per share, inclusive. The price reported in column 4 above reflects the average sale price per share. The Reporting Person hereby undertakes to provide the SEC staff, the Issuer or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote.

Of these shares, 20,754 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 21, 2025.

Transaction executed in multiple trades at prices ranging from $412.00 to $412.39 per share, inclusive. The price reported in column 4 above reflects the average sale price per share. The Reporting Person hereby undertakes to provide the SEC staff, the Issuer or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote.

Of these shares, 751 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

Represents shares earned in respect to PSU's granted in 2023 that have satisfied certain performance conditions.

Represents shares earned with respect to PSUs granted in 2023 that have satisfied certain performance conditions.

These shares were retained by the Company at the election of the Reporting Person pursuant to a procedure approved by the Compensation Committee of the Board of Directors to satisfy the Company's tax withholding requirements (based on the closing price of the Company's common stock on the release date) arising from the release of restrictions as permitted by the plan pursuant to which the restricted stock unit award was made.

Of these shares, 1,505 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

These shares were retained by the Company at the election of the Reporting Person pursuant to a procedure approved by the Compensation Committee of the Board of Directors to satisfy the Company's tax withholding requirements (based on the closing price of the Company's common stock on the release date) arising from the release of restrictions as permitted by the plan pursuant to which the restricted stock unit award was made.

Of these shares, 20,754 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 6, 2025.

Of these shares, 751 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 6, 2025.

Of these shares, 751 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 6, 2025.

Of these shares, 751 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 24, 2025.

Of these shares, 751 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

Represents the grant of time-vested restricted stock units that will vest in one-third increments on each of December 31, 2026, and the next two anniversaries thereof, provided the service conditions are satisfied.

Of these shares, 6,402 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

Represents the grant of time-vested restricted stock units that will vest in one-third increments on each of December 31, 2026, and the next two anniversaries thereof, provided the service conditions are satisfied.

Of these shares, 20,754 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

Represents the grant of time-vested restricted stock units that will vest in one-third increments on each of December 31, 2026, and the next two anniversaries thereof, provided the service conditions are satisfied.

Of these shares, 1,505 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

Represents the grant of time-vested restricted stock units that will vest in one-third increments on each of December 31, 2026, and the next two anniversaries thereof, provided the service conditions are satisfied.

Of these shares, 38,000 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

These shares were retained by the Company at the election of the Reporting Person pursuant to a procedure approved by the Compensation Committee of the Board of Directors to satisfy the Company's tax withholding requirements (based on the closing price of the Company's common stock on the release date) arising from the release of restrictions as permitted by the plan pursuant to which the restricted stock unit award was made.

These shares were retained by the Company at the election of the Reporting Person pursuant to a procedure approved by the Compensation Committee of the Board of Directors to satisfy the Company's tax withholding requirements (based on the closing price of the Company's common stock on the release date) arising from the release of restrictions as permitted by the plan pursuant to which the restricted stock unit award was made.

The total share ownership includes 125 shares acquired under the Company's 2019 Employee Stock Purchase Plan.

These shares were retained by the Company at the election of the Reporting Person pursuant to a procedure approved by the Compensation Committee of the Board of Directors to satisfy the Company's tax withholding requirements (based on the closing price of the Company's common stock on the release date) arising from the release of restrictions as permitted by the plan pursuant to which the restricted stock unit award was made.

The total share ownership includes 65 shares acquired under the Company's 2019 Employee Stock Purchase Plan.

These shares were retained by the Company at the election of the Reporting Person pursuant to a procedure approved by the Compensation Committee of the Board of Directors to satisfy the Company's tax withholding requirements (based on the closing price of the Company's common stock on the release date) arising from the release of restrictions as permitted by the plan pursuant to which the restricted stock unit award was made.

The total share ownership includes 141 shares acquired under the Company's 2019 Employee Stock Purchase Plan.

Reflects a gift of common stock to a donor-advised charitable fund.

Reflects a gift of common stock to a charitable organization.

Represents the grant of time-vested restricted stock units that will vest in one-third increments on each of December 31, 2025, and the next two anniversaries thereof, provided the service conditions are satisfied.

Of these shares, 8,862 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

These shares were retained by the Company at the election of the Reporting Person pursuant to a procedure approved by the Compensation Committee of the Board of Directors to satisfy the Company's tax withholding requirements (based on the closing price of the Company's common stock on the release date) arising from the release of restrictions as permitted by the plan pursuant to which the restricted stock unit award was made.

Represents the grant of time-vested restricted stock units that will vest in one-third increments on each of December 31, 2025 and the next two anniversaries thereof, provided the service conditions are satisfied.

These shares were awarded to the Reporting Person by the Company pursuant to the Company's standard director compensation arrangements for non-employee directors. The shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

These shares were awarded to the Reporting Person by the Company pursuant to the Company's standard director compensation arrangements for non-employee directors. The shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

Represents the grant of restricted stock units awarded to the Reporting Person in connection with his joining the Issuer. The award will vest in one-third increments on each of July 10, 2026 and the next two anniversaries thereof, providing the service conditions are satisfied.

Of these shares, 3,311 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 17, 2025.

Transaction executed in multiple trades, all at a price of $206.58.

Of these shares, 751 shares are subject to restrictions on their sale or other transfer and to forfeiture under certain circumstances.

These shares were awarded to the Reporting Person by the Company pursuant to the Company's standard director compensation arrangements for non-employee directors.

These shares were awarded to the Reporting Person by the Company pursuant to the Company's standard director compensation arrangements for non-employee directors.