# EDGAR Filing Document

**Accession Number:** 0001103804
**File Stem:** 0000905148-25-002998
**Filing Date:** 2025-8
**Character Count:** 41185
**Document Hash:** 401a379b2d135158c228cfe34d0aaf7e
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000905148-25-002998.hdr.sgml**: 20250814

**ACCESSION NUMBER**: 0000905148-25-002998

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

**PUBLIC DOCUMENT COUNT**: 2

**FILED AS OF DATE**: 20250814

**DATE AS OF CHANGE**: 20250814

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Trevi Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0001563880
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 450834299
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13G/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-91005
- **FILM NUMBER:** 251221313

**BUSINESS ADDRESS:**
- **STREET 1:** 195 CHURCH STREET
- **STREET 2:** 16TH FLOOR
- **CITY:** NEW HAVEN
- **STATE:** CT
- **ZIP:** 06510
- **BUSINESS PHONE:** 203-304-2499

**MAIL ADDRESS:**
- **STREET 1:** 195 CHURCH STREET
- **STREET 2:** 16TH FLOOR
- **CITY:** NEW HAVEN
- **STATE:** CT
- **ZIP:** 06510
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** VIKING GLOBAL INVESTORS LP
- **CENTRAL INDEX KEY:** 0001103804

**ORGANIZATION NAME:**
- **EIN:** 134055118
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

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

**BUSINESS ADDRESS:**
- **STREET 1:** 600 WASHINGTON BLVD.
- **STREET 2:** FLOOR 11
- **CITY:** STAMFORD
- **STATE:** CT
- **ZIP:** 06901
- **BUSINESS PHONE:** 212-672-7050

**MAIL ADDRESS:**
- **STREET 1:** 600 WASHINGTON BLVD.
- **STREET 2:** FLOOR 11
- **CITY:** STAMFORD
- **STATE:** CT
- **ZIP:** 06901

## Exhibit 99.1

EXHIBIT A - JOINT FILING AGREEMENT

This joint filing agreement is made and entered into as of this 14th day of August, 2025, by and among Viking Global Investors LP, Viking Global Opportunities Parent GP LLC, Viking Global Opportunities GP LLC, Viking Global Opportunities Portfolio GP LLC, Viking Global Opportunities Illiquid Investments Sub-Master LP, Viking Global Opportunities Drawdown GP LLC, Viking Global Opportunities Drawdown Portfolio GP LLC, Viking Global Opportunities Drawdown (Aggregator) LP, O. Andreas Halvorsen, David C. Ott and Rose S. Shabet.

The parties to this Agreement hereby agree to prepare jointly and file timely (and otherwise to deliver as appropriate) all filings on any Forms 3, 4, or 5 or Schedules 13D or 13G, and any and all amendments thereto and any other documents relating thereto (collectively, the "Filings") as required to be filed pursuant to the Securities Exchange Act of 1934, as amended. The parties to this Agreement further agree and covenant that each will fully cooperate with such other parties in the preparation, timely filing, and delivery of all such Filings.

IN WITNESS WHEREOF, the parties hereto have executed this agreement as of the date first set forth above.

Dated: August 14, 2025

---

| | |
|:---|:---|
| By: | /s/ Scott M. Hendler |
| Name: | Scott M. Hendler on behalf of O. Andreas Halvorsen (1) |
| By: | /s/ Scott M. Hendler |
| Name: | Scott M. Hendler on behalf of David C. Ott (2) |
| By: | /s/ Scott M. Hendler |
| Name: | Scott M. Hendler on behalf of Rose S. Shabet (3) |

---

(1) Scott M. Hendler is signing on behalf of O. Andreas Halvorsen, individually and as an Executive Committee Member of VIKING GLOBAL PARTNERS LLC, on behalf of VIKING GLOBAL INVESTORS LP, and as an Executive Committee Member of VIKING GLOBAL OPPORTUNITIES PARENT GP LLC, on behalf of itself and VIKING GLOBAL OPPORTUNITIES GP LLC, VIKING GLOBAL OPPORTUNITIES PORTFOLIO GP LLC, VIKING GLOBAL OPPORTUNITIES ILLIQUID INVESTMENTS SUB-MASTER LP, VIKING GLOBAL OPPORTUNITIES DRAWDOWN GP LLC, VIKING GLOBAL OPPORTUNITIES DRAWDOWN PORTFOLIO GP LLC and VIKING GLOBAL OPPORTUNITIES DRAWDOWN (AGGREGATOR) LP, pursuant to an authorization and designation letter dated February 9, 2021, which was previously filed with the Commission as an exhibit to a Form 13G filed by Mr. Halvorsen on February 12, 2021 (SEC File No. 005-49737).

(2) Scott M. Hendler is signing on behalf of David C. Ott, individually and as an Executive Committee Member of VIKING GLOBAL PARTNERS LLC, on behalf of VIKING GLOBAL INVESTORS LP, and as an Executive Committee Member of VIKING GLOBAL OPPORTUNITIES PARENT GP LLC, on behalf of itself and VIKING GLOBAL OPPORTUNITIES GP LLC, VIKING GLOBAL OPPORTUNITIES PORTFOLIO GP LLC, VIKING GLOBAL OPPORTUNITIES ILLIQUID INVESTMENTS SUB-MASTER LP, VIKING GLOBAL OPPORTUNITIES DRAWDOWN GP LLC, VIKING GLOBAL OPPORTUNITIES DRAWDOWN PORTFOLIO GP LLC and VIKING GLOBAL OPPORTUNITIES DRAWDOWN (AGGREGATOR) LP, pursuant to an authorization and designation letter dated February 9, 2021, which was previously filed with the Commission as an exhibit to a Form 13G filed by Mr. Halvorsen on February 12, 2021 (SEC File No. 005-49737).

(3) Scott M. Hendler is signing on behalf of Rose S. Shabet, individually and as an Executive Committee Member of VIKING GLOBAL PARTNERS LLC, on behalf of VIKING GLOBAL INVESTORS LP, and as an Executive Committee Member of VIKING GLOBAL OPPORTUNITIES PARENT GP LLC, on behalf of itself and VIKING GLOBAL OPPORTUNITIES GP LLC, VIKING GLOBAL OPPORTUNITIES PORTFOLIO GP LLC, VIKING GLOBAL OPPORTUNITIES ILLIQUID INVESTMENTS SUB-MASTER LP, VIKING GLOBAL OPPORTUNITIES DRAWDOWN GP LLC, VIKING GLOBAL OPPORTUNITIES DRAWDOWN PORTFOLIO GP LLC and VIKING GLOBAL OPPORTUNITIES DRAWDOWN (AGGREGATOR) LP, pursuant to an authorization and designation letter dated February 9, 2021, which was previously filed with the Commission as an exhibit to a Form 13G filed by Mr. Halvorsen on February 12, 2021 (SEC File No. 005-49737).

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

## SCHEDULE 13G

### Under the Securities Exchange Act of 1934

**(Amendment No. 4)**

**Issuer:** Trevi Therapeutics, Inc.

**Title of Class of Securities:** Common Stock, $0.001 par value per share

**CUSIP Number:** 89532M101

**Date of Event Which Requires Filing of this Statement:** 06/30/2025

**Check the appropriate box to designate the rule pursuant to which this Schedule is filed:**

- [ ] Rule 13d-1(b)

- [x] Rule 13d-1(c)

- [ ] Rule 13d-1(d)

---

| 1. | Names of Reporting Persons<br>VIKING GLOBAL INVESTORS LP | Names of Reporting Persons<br>VIKING GLOBAL INVESTORS LP |
|:---|:---|:---|:---|
| 2. | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] |
| 3. | SEC Use Only | SEC Use Only |
| 4. | Citizenship or Place of Organization<br>DE | Citizenship or Place of Organization<br>DE |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 5. | Sole Voting Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 6. | Shared Voting Power<br>7505694 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 7. | Sole Dispositive Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 8. | Shared Dispositive Power<br>7505694 |
| 9. | Aggregate Amount Beneficially Owned by Each Reporting Person<br>7505694 | Aggregate Amount Beneficially Owned by Each Reporting Person<br>7505694 |
| 10. | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] |
| 11. | Percent of Class Represented by Amount in Row (9)<br>5.9% | Percent of Class Represented by Amount in Row (9)<br>5.9% |
| 12. | Type of Reporting Person (See Instructions)<br>PN | Type of Reporting Person (See Instructions)<br>PN |

**Comment for Type of Reporting Person:** See Item 4

---

| 1. | Names of Reporting Persons<br>Viking Global Opportunities Parent GP LLC | Names of Reporting Persons<br>Viking Global Opportunities Parent GP LLC |
|:---|:---|:---|:---|
| 2. | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] |
| 3. | SEC Use Only | SEC Use Only |
| 4. | Citizenship or Place of Organization<br>DE | Citizenship or Place of Organization<br>DE |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 5. | Sole Voting Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 6. | Shared Voting Power<br>7505694 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 7. | Sole Dispositive Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 8. | Shared Dispositive Power<br>7505694 |
| 9. | Aggregate Amount Beneficially Owned by Each Reporting Person<br>7505694 | Aggregate Amount Beneficially Owned by Each Reporting Person<br>7505694 |
| 10. | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] |
| 11. | Percent of Class Represented by Amount in Row (9)<br>5.9% | Percent of Class Represented by Amount in Row (9)<br>5.9% |
| 12. | Type of Reporting Person (See Instructions)<br>OO | Type of Reporting Person (See Instructions)<br>OO |

**Comment for Type of Reporting Person:** See Item 4

---

| 1. | Names of Reporting Persons<br>Viking Global Opportunities GP LLC | Names of Reporting Persons<br>Viking Global Opportunities GP LLC |
|:---|:---|:---|:---|
| 2. | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] |
| 3. | SEC Use Only | SEC Use Only |
| 4. | Citizenship or Place of Organization<br>DE | Citizenship or Place of Organization<br>DE |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 5. | Sole Voting Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 6. | Shared Voting Power<br>5028815 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 7. | Sole Dispositive Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 8. | Shared Dispositive Power<br>5028815 |
| 9. | Aggregate Amount Beneficially Owned by Each Reporting Person<br>5028815 | Aggregate Amount Beneficially Owned by Each Reporting Person<br>5028815 |
| 10. | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] |
| 11. | Percent of Class Represented by Amount in Row (9)<br>3.9% | Percent of Class Represented by Amount in Row (9)<br>3.9% |
| 12. | Type of Reporting Person (See Instructions)<br>OO | Type of Reporting Person (See Instructions)<br>OO |

**Comment for Type of Reporting Person:** See Item 4

---

| 1. | Names of Reporting Persons<br>Viking Global Opportunities Portfolio GP LLC | Names of Reporting Persons<br>Viking Global Opportunities Portfolio GP LLC |
|:---|:---|:---|:---|
| 2. | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] |
| 3. | SEC Use Only | SEC Use Only |
| 4. | Citizenship or Place of Organization<br>DE | Citizenship or Place of Organization<br>DE |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 5. | Sole Voting Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 6. | Shared Voting Power<br>5028815 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 7. | Sole Dispositive Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 8. | Shared Dispositive Power<br>5028815 |
| 9. | Aggregate Amount Beneficially Owned by Each Reporting Person<br>5028815 | Aggregate Amount Beneficially Owned by Each Reporting Person<br>5028815 |
| 10. | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] |
| 11. | Percent of Class Represented by Amount in Row (9)<br>3.9% | Percent of Class Represented by Amount in Row (9)<br>3.9% |
| 12. | Type of Reporting Person (See Instructions)<br>OO | Type of Reporting Person (See Instructions)<br>OO |

**Comment for Type of Reporting Person:** See Item 4

---

| 1. | Names of Reporting Persons<br>Viking Global Opportunities Illiquid Investments Sub-Master LP | Names of Reporting Persons<br>Viking Global Opportunities Illiquid Investments Sub-Master LP |
|:---|:---|:---|:---|
| 2. | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] |
| 3. | SEC Use Only | SEC Use Only |
| 4. | Citizenship or Place of Organization<br>E9 | Citizenship or Place of Organization<br>E9 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 5. | Sole Voting Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 6. | Shared Voting Power<br>5028815 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 7. | Sole Dispositive Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 8. | Shared Dispositive Power<br>5028815 |
| 9. | Aggregate Amount Beneficially Owned by Each Reporting Person<br>5028815 | Aggregate Amount Beneficially Owned by Each Reporting Person<br>5028815 |
| 10. | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] |
| 11. | Percent of Class Represented by Amount in Row (9)<br>3.9% | Percent of Class Represented by Amount in Row (9)<br>3.9% |
| 12. | Type of Reporting Person (See Instructions)<br>PN | Type of Reporting Person (See Instructions)<br>PN |

**Comment for Type of Reporting Person:** See Item 4

---

| 1. | Names of Reporting Persons<br>Viking Global Opportunities Drawdown GP LLC | Names of Reporting Persons<br>Viking Global Opportunities Drawdown GP LLC |
|:---|:---|:---|:---|
| 2. | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] |
| 3. | SEC Use Only | SEC Use Only |
| 4. | Citizenship or Place of Organization<br>DE | Citizenship or Place of Organization<br>DE |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 5. | Sole Voting Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 6. | Shared Voting Power<br>2476879 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 7. | Sole Dispositive Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 8. | Shared Dispositive Power<br>2476879 |
| 9. | Aggregate Amount Beneficially Owned by Each Reporting Person<br>2476879 | Aggregate Amount Beneficially Owned by Each Reporting Person<br>2476879 |
| 10. | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] |
| 11. | Percent of Class Represented by Amount in Row (9)<br>1.9% | Percent of Class Represented by Amount in Row (9)<br>1.9% |
| 12. | Type of Reporting Person (See Instructions)<br>OO | Type of Reporting Person (See Instructions)<br>OO |

**Comment for Type of Reporting Person:** See Item 4

---

| 1. | Names of Reporting Persons<br>Viking Global Opportunities Drawdown Portfolio GP LLC | Names of Reporting Persons<br>Viking Global Opportunities Drawdown Portfolio GP LLC |
|:---|:---|:---|:---|
| 2. | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] |
| 3. | SEC Use Only | SEC Use Only |
| 4. | Citizenship or Place of Organization<br>DE | Citizenship or Place of Organization<br>DE |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 5. | Sole Voting Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 6. | Shared Voting Power<br>2476879 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 7. | Sole Dispositive Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 8. | Shared Dispositive Power<br>2476879 |
| 9. | Aggregate Amount Beneficially Owned by Each Reporting Person<br>2476879 | Aggregate Amount Beneficially Owned by Each Reporting Person<br>2476879 |
| 10. | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] |
| 11. | Percent of Class Represented by Amount in Row (9)<br>1.9% | Percent of Class Represented by Amount in Row (9)<br>1.9% |
| 12. | Type of Reporting Person (See Instructions)<br>OO | Type of Reporting Person (See Instructions)<br>OO |

**Comment for Type of Reporting Person:** See Item 4

---

| 1. | Names of Reporting Persons<br>Viking Global Opportunities Drawdown (Aggregator) LP | Names of Reporting Persons<br>Viking Global Opportunities Drawdown (Aggregator) LP |
|:---|:---|:---|:---|
| 2. | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] |
| 3. | SEC Use Only | SEC Use Only |
| 4. | Citizenship or Place of Organization<br>E9 | Citizenship or Place of Organization<br>E9 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 5. | Sole Voting Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 6. | Shared Voting Power<br>2476879 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 7. | Sole Dispositive Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 8. | Shared Dispositive Power<br>2476879 |
| 9. | Aggregate Amount Beneficially Owned by Each Reporting Person<br>2476879 | Aggregate Amount Beneficially Owned by Each Reporting Person<br>2476879 |
| 10. | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] |
| 11. | Percent of Class Represented by Amount in Row (9)<br>1.9% | Percent of Class Represented by Amount in Row (9)<br>1.9% |
| 12. | Type of Reporting Person (See Instructions)<br>PN | Type of Reporting Person (See Instructions)<br>PN |

**Comment for Type of Reporting Person:** See Item 4

---

| 1. | Names of Reporting Persons<br>HALVORSEN OLE ANDREAS | Names of Reporting Persons<br>HALVORSEN OLE ANDREAS |
|:---|:---|:---|:---|
| 2. | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] |
| 3. | SEC Use Only | SEC Use Only |
| 4. | Citizenship or Place of Organization<br>Q8 | Citizenship or Place of Organization<br>Q8 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 5. | Sole Voting Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 6. | Shared Voting Power<br>7505694 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 7. | Sole Dispositive Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 8. | Shared Dispositive Power<br>7505694 |
| 9. | Aggregate Amount Beneficially Owned by Each Reporting Person<br>7505694 | Aggregate Amount Beneficially Owned by Each Reporting Person<br>7505694 |
| 10. | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] |
| 11. | Percent of Class Represented by Amount in Row (9)<br>5.9% | Percent of Class Represented by Amount in Row (9)<br>5.9% |
| 12. | Type of Reporting Person (See Instructions)<br>IN | Type of Reporting Person (See Instructions)<br>IN |

**Comment for Type of Reporting Person:** See Item 4

---

| 1. | Names of Reporting Persons<br>Ott David C. | Names of Reporting Persons<br>Ott David C. |
|:---|:---|:---|:---|
| 2. | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] |
| 3. | SEC Use Only | SEC Use Only |
| 4. | Citizenship or Place of Organization<br>X1 | Citizenship or Place of Organization<br>X1 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 5. | Sole Voting Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 6. | Shared Voting Power<br>7505694 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 7. | Sole Dispositive Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 8. | Shared Dispositive Power<br>7505694 |
| 9. | Aggregate Amount Beneficially Owned by Each Reporting Person<br>7505694 | Aggregate Amount Beneficially Owned by Each Reporting Person<br>7505694 |
| 10. | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] |
| 11. | Percent of Class Represented by Amount in Row (9)<br>5.9% | Percent of Class Represented by Amount in Row (9)<br>5.9% |
| 12. | Type of Reporting Person (See Instructions)<br>IN | Type of Reporting Person (See Instructions)<br>IN |

**Comment for Type of Reporting Person:** See Item 4

---

| 1. | Names of Reporting Persons<br>Shabet Rose Sharon | Names of Reporting Persons<br>Shabet Rose Sharon |
|:---|:---|:---|:---|
| 2. | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [x] |
| 3. | SEC Use Only | SEC Use Only |
| 4. | Citizenship or Place of Organization<br>X1 | Citizenship or Place of Organization<br>X1 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 5. | Sole Voting Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 6. | Shared Voting Power<br>7505694 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 7. | Sole Dispositive Power<br>0 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 8. | Shared Dispositive Power<br>7505694 |
| 9. | Aggregate Amount Beneficially Owned by Each Reporting Person<br>7505694 | Aggregate Amount Beneficially Owned by Each Reporting Person<br>7505694 |
| 10. | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] |
| 11. | Percent of Class Represented by Amount in Row (9)<br>5.9% | Percent of Class Represented by Amount in Row (9)<br>5.9% |
| 12. | Type of Reporting Person (See Instructions)<br>IN | Type of Reporting Person (See Instructions)<br>IN |

**Comment for Type of Reporting Person:** See Item 4

---

**Item 1(a). Name of Issuer:**
Trevi Therapeutics, Inc.

**Item 1(b). Address of Issuer's Principal Executive Offices:**
195 Church Street, 16th Floor, New Haven, Connecticut, 06510

**Item 2(a). Name of Person Filing:**
Viking Global Investors LP ("VGI"),
Viking Global Opportunities Parent GP LLC ("Opportunities Parent"),
Viking Global Opportunities GP LLC ("Opportunities GP"),
Viking Global Opportunities Portfolio GP LLC ("Opportunities Portfolio GP"),
Viking Global Opportunities Illiquid Investments Sub-Master LP ("VGOP"),
Viking Global Opportunities Drawdown GP LLC ("VGOD GP"),
Viking Global Opportunities Drawdown Portfolio GP LLC ("VGOD Portfolio GP"),
Viking Global Opportunities Drawdown (Aggregator) LP ("VGOD"),
O. Andreas Halvorsen, David C. Ott and Rose S. Shabet (collectively, the "Reporting Persons")

**Item 2(b). Address of Principal Business Office:**
The business address of each of the Reporting Persons is: 600 Washington Boulevard, Floor 11, Stamford, Connecticut 06901.

**Item 2(c). Citizenship:**
VGI is a Delaware limited partnership; Opportunities Parent, Opportunities GP, Opportunities Portfolio GP, VGOD GP and VGOD Portfolio GP are Delaware limited liability companies; VGOP and VGOD are Cayman Islands exempted limited partnerships; O. Andreas Halvorsen is a citizen of Norway; and David C. Ott and Rose S. Shabet are citizens of the United States.

**Item 2(d). Title of Class of Securities:**
Common Stock, $0.001 par value per share

**Item 2(e). CUSIP Number:**
89532M101

**Item 3. If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:**

(a) [ ] Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o).

(b) [ ] Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c).

(c) [ ] Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c).

(d) [ ] Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8).

(e) [ ] An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);

(f) [ ] An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);

(g) [ ] A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);

(h) [ ] A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i) [ ] A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j) [ ] A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), if filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:

(k) [ ] Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).

**Item 4. Ownership:**

**(a) Amount beneficially owned:**

This Statement on Schedule 13G relates to shares of Common Stock and pre-funded warrants to purchase shares of Common Stock with an exercise price of $0.001 per share (the "Warrants") held directly by VGOP and VGOD.
VGI: 7,505,694
VGI provides managerial services to VGOP and VGOD. VGI has the authority to dispose of and vote the shares of Common Stock that VGOP and VGOD directly own or have the right to purchase upon exercise of the Warrants.  VGI does not directly own any shares of Common Stock or Warrants.
Based on Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Act"), VGI may be deemed to beneficially own the shares of Common Stock that VGOP and VGOD directly own or have the right to purchase upon exercise of the Warrants.
VGI beneficially owns 7,505,694 shares of Common Stock consisting of (i) 1,033,810 and 509,190 shares of Common Stock directly owned by VGOP and VGOD, respectively, and (ii) 3,995,005 and 1,967,689 shares of Common Stock beneficially owned by VGOP and VGOD, respectively, which VGOP and VGOD have the right to purchase upon exercise of the Warrants.
Opportunities Parent: 7,505,694
Opportunities Parent is the sole member of Opportunities GP, which has the authority to dispose of and vote the shares of Common Stock controlled by Opportunities Portfolio GP (which consists of the shares of Common Stock that VGOP directly owns or has the right to purchase upon exercise of the Warrants), and is the sole member of VGOD GP, which has the authority to dispose of and vote the shares of Common Stock controlled by VGOD Portfolio GP (which consists of the shares of Common Stock that VGOD directly owns or has the right to purchase upon exercise of the Warrants). Opportunities Parent does not directly own any shares of Common Stock or Warrants.
Based on Rule 13d-3 under the Act, Opportunities Parent may be deemed to beneficially own the shares of Common Stock that VGOP and VGOD directly own or have the right to purchase upon exercise of the Warrants.
Opportunities Parent beneficially owns 7,505,694 shares of Common Stock consisting of (i) 1,033,810 and 509,190 shares of Common Stock directly owned by VGOP and VGOD, respectively, and (ii) 3,995,005 and 1,967,689 shares of Common Stock beneficially owned by VGOP and VGOD, respectively, which VGOP and VGOD have the right to purchase upon exercise of the Warrants.
Opportunities GP: 5,028,815
Opportunities GP serves as the sole member of Opportunities Portfolio GP and has the authority to dispose of and vote the shares of Common Stock controlled by Opportunities Portfolio GP, which consists of the shares of Common Stock that VGOP directly owns or has the right to purchase upon exercise of the Warrants. In addition, Opportunities GP is the general partner of each of Viking Global Opportunities Intermediate LP, Viking Global Opportunities III LP, and Viking Global Opportunities LP. Opportunities GP does not directly own any shares of Common Stock or Warrants.
Based on Rule 13d-3 under the Act, Opportunities GP may be deemed to beneficially own the shares of Common Stock that VGOP directly owns or has the right to purchase upon exercise of the Warrants.
Opportunities GP beneficially owns 5,028,815 shares of Common Stock consisting of 1,033,810 shares of Common Stock directly owned by VGOP and 3,995,005 shares of Common Stock beneficially owned by VGOP, which VGOP has the right to purchase upon exercise of the Warrants.
Opportunities Portfolio GP: 5,028,815
Opportunities Portfolio GP serves as the general partner of VGOP and has the authority to dispose of and vote the shares of Common Stock that VGOP directly owns or has the right to purchase upon exercise of the Warrants. Opportunities Portfolio GP does not directly own any shares of Common Stock or Warrants.
Based on Rule 13d-3 under the Act, Opportunities Portfolio GP may be deemed to beneficially own the shares of Common Stock that VGOP directly owns or has the right to purchase upon exercise of the Warrants.
Opportunities Portfolio GP beneficially owns 5,028,815 shares of Common Stock consisting of 1,033,810 shares of Common Stock directly owned by VGOP and 3,995,005 shares of Common Stock beneficially owned by VGOP, which VGOP has the right to purchase upon exercise of the Warrants.
VGOP: 5,028,815
VGOP has the authority to dispose of and vote the 1,033,810 shares of Common Stock that it owns and the 3,995,005 shares of Common Stock it has the right to purchase upon exercise of the Warrants directly owned by it, which power may be exercised by its general partner, Opportunities Portfolio GP, and by VGI, an affiliate of Opportunities Portfolio GP, which provides managerial services to VGOP.
Viking Global Opportunities LP (a Delaware limited partnership) and Viking Global Opportunities III LP (a Cayman Islands exempted limited partnership), through its investment in Viking Global Opportunities Intermediate LP (a Cayman Islands exempted limited partnership), invest substantially all of their assets in Viking Global Opportunities Master LP (a Cayman Islands exempted limited partnership), which in turn invests through VGOP.
VGOD GP: 2,476,879
VGOD GP serves as the sole member of VGOD Portfolio GP and has the authority to dispose of and vote the shares of Common Stock controlled by VGOD Portfolio GP, which consists of the shares of Common Stock that VGOD directly owns or has the right to purchase upon exercise of the Warrants. In addition, VGOD GP is the general partner of each of Viking Global Opportunities Drawdown (Internal) LP, Viking Global Opportunities Drawdown (Onshore) LP, and Viking Global Opportunities Drawdown (Offshore) LP. VGOD GP does not directly own any shares of Common Stock or Warrants.
Based on Rule 13d-3 under the Act, VGOD GP may be deemed to beneficially own the shares of Common Stock that VGOD directly owns or has the right to purchase upon exercise of the Warrants.
VGOD GP beneficially owns 2,476,879 shares of Common Stock consisting of 509,190 shares of Common Stock directly owned by VGOD and 1,967,689 shares of Common Stock beneficially owned by VGOD, which VGOD has the right to purchase upon exercise of the Warrants.
VGOD Portfolio GP: 2,476,879
VGOD Portfolio GP serves as the general partner of VGOD and has the authority to dispose of and vote the shares of Common Stock that VGOD directly owns or has the right to purchase upon exercise of the Warrants. VGOD Portfolio GP does not directly own any shares of Common Stock or Warrants.
Based on Rule 13d-3 under the Act, VGOD Portfolio GP may be deemed to beneficially own the shares of Common Stock that VGOD directly owns or has the right to purchase upon exercise of the Warrants.
VGOD Portfolio GP beneficially owns 2,476,879 shares of Common Stock consisting of 509,190 shares of Common Stock directly owned by VGOD and 1,967,689 shares of Common Stock beneficially owned by VGOD, which VGOD has the right to purchase upon exercise of the Warrants.
VGOD: 2,476,879
VGOD has the authority to dispose of and vote the 509,190 shares of Common Stock that it directly owns and the 1,967,689 shares of Common Stock it has the right to purchase upon exercise of the Warrants directly owned by it, which power may be exercised by VGOD Portfolio GP, and by VGI, an affiliate of VGOD Portfolio GP, which provides managerial services to VGOD.
Viking Global Opportunities Drawdown (Offshore) LP (a Cayman Islands exempted limited partnership) and Viking Global Opportunities Drawdown (Internal) LP (a Delaware limited partnership), through its investment in Viking Global Opportunities Drawdown (Onshore) LP (a Delaware limited partnership), invest substantially all of their assets in VGOD.
O. Andreas Halvorsen, David C. Ott and Rose S. Shabet: 7,505,694
Mr. Halvorsen, Mr. Ott and Ms. Shabet, as Executive Committee Members of Viking Global Partners LLC (general partner of VGI) and Opportunities Parent, have shared authority to dispose of and vote the shares of Common Stock beneficially owned by VGI and Opportunities Parent. None of Mr. Halvorsen, Mr. Ott and Ms. Shabet directly owns any shares of Common Stock or Warrants.
Based on Rule 13d-3 under the Act, each may be deemed to beneficially own the shares of Common Stock that VGOP and VGOD directly own or have the right to purchase upon exercise of the Warrants.
Each of Mr. Halvorsen, Mr. Ott and Ms. Shabet beneficially owns 7,505,694 shares of Common Stock consisting of (i) 1,033,810 and 509,190 shares of Common Stock directly owned by VGOP and VGOD, respectively, and (ii) 3,995,005 and 1,967,689 shares of Common Stock beneficially owned by VGOP and VGOD, respectively, which VGOP and VGOD have the right to purchase upon exercise of the Warrants.

**(b) Percent of class:**

The percentages set forth herein are based on (i) 121,775,753 shares of Common Stock outstanding as of June 30, 2025, as reported in the Issuer's quarterly report on Form 10-Q, filed with the Securities and Exchange Commission (the "Commission") on August 7, 2025, and (ii) 5,962,694 shares of Common Stock that the Reporting Persons currently have the right to purchase upon exercise of the Warrants.
VGI: 5.9%
Opportunities Parent: 5.9%
Opportunities GP: 3.9%
Opportunities Portfolio GP: 3.9%
VGOP: 3.9%
VGOD GP: 1.9%
VGOD Portfolio GP: 1.9%
VGOD: 1.9%
O. Andreas Halvorsen, David C. Ott and Rose S. Shabet: 5.9%

**(c) Number of shares as to which the person has:**

**(i) Sole power to vote or to direct the vote:**

VGI: 0
Opportunities Parent: 0
Opportunities GP: 0
Opportunities Portfolio GP: 0
VGOP: 0
VGOD GP: 0
VGOD Portfolio GP: 0
VGOD: 0
O. Andreas Halvorsen, David C. Ott and Rose S. Shabet: 0

**(ii) Shared power to vote or to direct the vote:**

VGI: 7,505,694
Opportunities Parent: 7,505,694
Opportunities GP: 5,028,815
Opportunities Portfolio GP: 5,028,815
VGOP: 5,028,815
VGOD GP: 2,476,879
VGOD Portfolio GP: 2,476,879
VGOD: 2,476,879
O. Andreas Halvorsen, David C. Ott and Rose S. Shabet: 7,505,694

**(iii) Sole power to dispose or to direct the disposition of:**

VGI: 0
Opportunities Parent: 0
Opportunities GP: 0
Opportunities Portfolio GP: 0
VGOP: 0
VGOD GP: 0
VGOD Portfolio GP: 0
VGOD: 0
O. Andreas Halvorsen, David C. Ott and Rose S. Shabet: 0

**(iv) Shared power to dispose or to direct the disposition of:**

VGI: 7,505,694
Opportunities Parent: 7,505,694
Opportunities GP: 5,028,815
Opportunities Portfolio GP: 5,028,815
VGOP: 5,028,815
VGOD GP: 2,476,879
VGOD Portfolio GP: 2,476,879
VGOD: 2,476,879
O. Andreas Halvorsen, David C. Ott and Rose S. Shabet: 7,505,694

**Item 5. Ownership of Five Percent or Less of a Class.**

[x] If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following.

**Item 6. Ownership of More than 5 Percent on Behalf of Another Person.**

The response to Item 4 is incorporated by reference herein.

**Item 7. Identification and Classification of the Subsidiary**

Not Applicable

**Item 8. Identification and Classification of Members of the Group**

Not Applicable

**Item 9. Notice of Dissolution of Group**

Not Applicable

**Item 10. Certification:**

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

### 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.

**VIKING GLOBAL INVESTORS LP**

**Date:** 08/14/2025

**By:** /s/ Scott M. Hendler

**Name & Title:** Scott M. Hendler on behalf of VIKING GLOBAL INVESTORS LP (1)(2)(3)

**Viking Global Opportunities Parent GP LLC**

**Date:** 08/14/2025

**By:** /s/ Scott M. Hendler

**Name & Title:** Scott M. Hendler on behalf of Viking Global Opportunities Parent GP LLC (1)(2)(3)

**Viking Global Opportunities GP LLC**

**Date:** 08/14/2025

**By:** /s/ Scott M. Hendler

**Name & Title:** Scott M. Hendler on behalf of Viking Global Opportunities GP LLC (1)(2)(3)

**Viking Global Opportunities Portfolio GP LLC**

**Date:** 08/14/2025

**By:** /s/ Scott M. Hendler

**Name & Title:** Scott M. Hendler on behalf of Viking Global Opportunities Portfolio GP LLC (1)(2)(3)

**Viking Global Opportunities Illiquid Investments Sub-Master LP**

**Date:** 08/14/2025

**By:** /s/ Scott M. Hendler

**Name & Title:** Scott M. Hendler on behalf of Viking Global Opportunities Illiquid Investments Sub-Master LP (1)(2)(3)

**Viking Global Opportunities Drawdown GP LLC**

**Date:** 08/14/2025

**By:** /s/ Scott M. Hendler

**Name & Title:** Scott M. Hendler on behalf of Viking Global Opportunities Drawdown GP LLC (1)(2)(3)

**Viking Global Opportunities Drawdown Portfolio GP LLC**

**Date:** 08/14/2025

**By:** /s/ Scott M. Hendler

**Name & Title:** Scott M. Hendler on behalf of Viking Global Opportunities Drawdown Portfolio GP LLC (1)(2)(3)

**Viking Global Opportunities Drawdown (Aggregator) LP**

**Date:** 08/14/2025

**By:** /s/ Scott M. Hendler

**Name & Title:** Scott M. Hendler on behalf of Viking Global Opportunities Drawdown (Aggregator) LP (1)(2)(3)

**HALVORSEN OLE ANDREAS**

**Date:** 08/14/2025

**By:** /s/ Scott M. Hendler

**Name & Title:** Scott M. Hendler on behalf of O. Andreas Halvorsen (1)

**Ott David C.**

**Date:** 08/14/2025

**By:** /s/ Scott M. Hendler

**Name & Title:** Scott M. Hendler on behalf of David C. Ott (2)

**Shabet Rose Sharon**

**Date:** 08/14/2025

**By:** /s/ Scott M. Hendler

**Name & Title:** Scott M. Hendler on behalf of Rose S. Shabet (3)