# EDGAR Filing Document

**Accession Number:** 0001709682
**File Stem:** 0001213900-25-100831
**Filing Date:** 2025-10
**Character Count:** 12957
**Document Hash:** ceb1c5ee910797061b21e5f7a7e735ca
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001213900-25-100831.hdr.sgml**: 20251021

**ACCESSION NUMBER**: 0001213900-25-100831

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D/A

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20251021

**DATE AS OF CHANGE**: 20251021

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Custom Truck One Source, Inc.
- **CENTRAL INDEX KEY:** 0001709682
- **STANDARD INDUSTRIAL CLASSIFICATION:** SERVICES-EQUIPMENT RENTAL & LEASING, NEC [7359]
- **ORGANIZATION NAME:** 07 Trade & Services
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-90085
- **FILM NUMBER:** 251407414

**BUSINESS ADDRESS:**
- **STREET 1:** 7701 INDEPENDENCE AVENUE
- **CITY:** KANSAS CITY
- **STATE:** MO
- **ZIP:** 64125
- **BUSINESS PHONE:** (816) 241-4888

**MAIL ADDRESS:**
- **STREET 1:** 7701 INDEPENDENCE AVENUE
- **CITY:** KANSAS CITY
- **STATE:** MO
- **ZIP:** 64125

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** NESCO HOLDINGS, INC.
- **DATE OF NAME CHANGE:** 20190730

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Capitol Investment Corp. IV
- **DATE OF NAME CHANGE:** 20170619
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** EIN MARK
- **CENTRAL INDEX KEY:** 0001246840

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A

**MAIL ADDRESS:**
- **STREET 1:** 7925 JONES BRANCH DR
- **STREET 2:** UNIT 102
- **CITY:** MCCLEAN
- **STATE:** VA
- **ZIP:** 22102

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**(Amendment No. 1)**

**Custom Truck One Source, Inc.**

*(Name of Issuer)*

**Common Stock**

*(Title of Class of Securities)*

**23204X103**

*(CUSIP Number)*

**Mark Ein**<br>2200 Wilson Blvd, Suite 102 #447<br>Arlington VA 22201<br>202-654-7001

*(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)*

**10/17/2025**

*(Date of Event Which Requires Filing of this Statement)*

| **CUSIP No.** | **23204X103** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Capitol Acquisition Management IV LLC** | Name of reporting person<br>**Capitol Acquisition Management IV LLC** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**0.00** | Aggregate amount beneficially owned by each reporting person<br>**0.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**0%** | Percent of class represented by amount in Row (11)<br>**0%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**OO** | Type of Reporting Person (See Instructions)<br>**OO** | |

---

| **CUSIP No.** | **23204X103** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Capitol Acquisition Founder IV LLC** | Name of reporting person<br>**Capitol Acquisition Founder IV LLC** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**0.00** | Aggregate amount beneficially owned by each reporting person<br>**0.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**0%** | Percent of class represented by amount in Row (11)<br>**0%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**OO** | Type of Reporting Person (See Instructions)<br>**OO** | |

---

| **CUSIP No.** | **23204X103** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Mark Ein** | Name of reporting person<br>**Mark Ein** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**X1** | Citizenship or place of organization<br>**X1** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**5159319.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**5159319.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**5159319.00** | Aggregate amount beneficially owned by each reporting person<br>**5159319.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**2.3%** | Percent of class represented by amount in Row (11)<br>**2.3%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

| **CUSIP No.** | **23204X103** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Dyson Dryden** | Name of reporting person<br>**Dyson Dryden** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**X1** | Citizenship or place of organization<br>**X1** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**0.00** | Aggregate amount beneficially owned by each reporting person<br>**0.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**0%** | Percent of class represented by amount in Row (11)<br>**0%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Stock

**(b) Name of Issuer:**
Custom Truck One Source, Inc.

**(c) Address of Issuer's Principal Executive Offices:**
7701 Independence Avenue, Kansas City, MO, 64125

This Amendment No. 1 to Schedule 13D (this "Amendment No. 1") amends and supplements the statement on Schedule 13D filed with the United States Securities and Exchange Commission on April 14, 2021 (the "Schedule 13D"), relating to the common stock, par value $0.0001 per share (the "Common Stock"), of Custom Truck One Source, Inc., a Delaware corporation (the "Issuer"), whose principal executive office is located at 7701 Independence Ave., Kansas City, MO 64125. Capitalized terms used herein without definition shall have the meaning set forth in the Schedule 13D.

**Item 4. Purpose of Transaction**

Item 4 of the Schedule 13D is hereby amended and supplemented with the following:

Distribution In-Kind

On October 17, 2025, Management IV distributed 3,670,279 shares of Common Stock to its members without consideration on a pro rata basis. As part of this distribution, Mr. Ein acquired 3,553,612 shares of Common Stock.

**Item 5. Interest in Securities of the Issuer**

**(a)**
Item 5 of the Schedule 13D is hereby amended and restated in its entirety as follows:

The beneficial ownership set forth herein is based on 226,559,586 shares of Common Stock outstanding as of July 28, 2025, as disclosed in the Issuer's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on July 30, 2025.

**(b)**
Mr. Ein is the record holder of 5,139,319 shares of Common Stock and options to purchase 20,000 shares of Common Stock that are currently exercisable.

**(c)**
Other than as described in Item 4, the Reporting Persons have not effected any other transactions in Common Stock during the past 60 days.

### SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Capitol Acquisition Management IV LLC

**Signature:** /s/ Mark Ein

**Name/Title:** Mark Ein, Chief Executive Officer

**Date:** 10/21/2025

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Capitol Acquisition Founder IV LLC

**Signature:** /s/ Dyson Dryden

**Name/Title:** Dyson Dryden, Chief Financial Officer

**Date:** 10/21/2025

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Mark Ein

**Signature:** /s/ Mark Ein

**Name/Title:** Mark Ein

**Date:** 10/21/2025

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Dyson Dryden

**Signature:** /s/ Dyson Dryden

**Name/Title:** Dyson Dryden

**Date:** 10/21/2025