# EDGAR Filing Document

**Accession Number:** 0000917286
**File Stem:** 0000917286-25-000135
**Filing Date:** 2025-9
**Character Count:** 7657
**Document Hash:** 638cc0a8306f42d371ab6facbe2fc200
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000917286-25-000135.hdr.sgml**: 20250922

**ACCESSION NUMBER**: 0000917286-25-000135

**CONFORMED SUBMISSION TYPE**: 497

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20250922

**DATE AS OF CHANGE**: 20250922

**EFFECTIVENESS DATE**: 20250922

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** FIDELITY HEREFORD STREET TRUST
- **CENTRAL INDEX KEY:** 0000917286

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 0430

**FILING VALUES:**
- **FORM TYPE:** 497
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 033-52577
- **FILM NUMBER:** 251329209

**BUSINESS ADDRESS:**
- **STREET 1:** 245 SUMMER STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02210
- **BUSINESS PHONE:** 617-563-7000

**MAIL ADDRESS:**
- **STREET 1:** 245 SUMMER STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02210

## Series and Classes Contracts Data

### Fidelity Government Money Market Fund (Series ID: S000007051)

---

|  |  |  |
|:---|:---|:---|
| Class Name                            | Ticker Symbol | Class ID   |
| Fidelity Government Money Market Fund | SPAXX         | C000019230 |

---

### Fidelity Money Market Fund (Series ID: S000007052)

---

|  |  |  |
|:---|:---|:---|
| Class Name                 | Ticker Symbol | Class ID   |
| Fidelity Money Market Fund | SPRXX         | C000019231 |

---

### Fidelity Treasury Only Money Market Fund (Series ID: S000007053)

---

|  |  |  |
|:---|:---|:---|
| Class Name                               | Ticker Symbol | Class ID   |
| Fidelity Treasury Only Money Market Fund | FDLXX         | C000019232 |
| Class OUS                                | FYIXX         | C000257340 |

---

### Fidelity Treasury Digital Fund (Series ID: S000089156)

---

|  |  |  |
|:---|:---|:---|
| Class Name      | Ticker Symbol | Class ID   |
| Liquidity Class | FYHXX         | C000255665 |
| OnChain         | FYOXX         | C000261149 |

---

## Series and Classes Contracts Data

### Fidelity Government Money Market Fund (Series ID: S000007051)

| Class ID   | Class Name                            | Ticker Symbol   |
|:---|:---|:---|
| C000019230 | Fidelity Government Money Market Fund | SPAXX           |

### Fidelity Money Market Fund (Series ID: S000007052)

| Class ID   | Class Name                 | Ticker Symbol   |
|:---|:---|:---|
| C000019231 | Fidelity Money Market Fund | SPRXX           |

### Fidelity Treasury Only Money Market Fund (Series ID: S000007053)

| Class ID   | Class Name                               | Ticker Symbol   |
|:---|:---|:---|
| C000019232 | Fidelity Treasury Only Money Market Fund | FDLXX           |
| C000257340 | Class OUS                                | FYIXX           |

### Fidelity Treasury Digital Fund (Series ID: S000089156)

| Class ID   | Class Name      | Ticker Symbol   |
|:---|:---|:---|
| C000255665 | Liquidity Class | FYHXX           |
| C000261149 | OnChain         | FYOXX           |

**Supplement to the Fidelity® Treasury Only Money Market Fund Class OUS**

**June 28, 2025 Prospectus**

The following information replaces similar information found in the "Investment Details" section under the "Principal Investment Risks" heading.

In response to market, economic, political, or other conditions, a fund may temporarily use a different investment strategy (including leaving a significant portion of the fund's assets uninvested or investing in repurchase agreements collateralized by U.S. Treasury obligations) for defensive purposes. Uninvested assets do not earn income for a fund, which may have a significant negative impact on the fund's yield and may prevent the fund from achieving its investment objective. The addition of repurchase agreements could cause a portion of the income from Fidelity® Treasury Only Money Market Fund to be subject to state and local income taxes.

TMN-PSTK-0925-100 1.9921542.100 September 22, 2025

**Supplement to the**

**Fidelity® Treasury Only Money Market Fund**

**Class OUS**

**June 28, 2025**

**STATEMENT OF ADDITIONAL INFORMATION**

*The following information replaces similar information found in the "Investment Policies and Limitations" section.*

**<u>Temporary Defensive Policies.</u>** Fidelity® Treasury Only Money Market Fund reserves the right to hold a substantial amount of uninvested cash for temporary, defensive purposes. In addition, Fidelity® Treasury Only Money Market Fund reserves the right to invest in repurchase agreements collateralized by U.S. Treasury obligations for temporary, defensive purposes.

TMN-SSTK-0925-100-1.9921543.100 September 22, 2025

**Supplement to the**

**Fidelity® Government Money Market Fund, Fidelity® Money Market Fund, and Fidelity® Treasury Only Money Market Fund**

**June 28, 2025**

**STATEMENT OF ADDITIONAL INFORMATION**

*The following information replaces similar information found in the "Investment Policies and Limitations" section.*

**<u>Temporary Defensive Policies.</u>** Each of Fidelity® Government Money Market Fund, Fidelity® Money Market Fund, and Fidelity® Treasury Only Money Market Fund reserves the right to hold a substantial amount of uninvested cash for temporary, defensive purposes. In addition, Fidelity® Treasury Only Money Market Fund reserves the right to invest in repurchase agreements collateralized by U.S. Treasury obligations for temporary, defensive purposes.

SMF-SSTK-0925-127-1.713588.127 September 22, 2025

**Supplement to the Fidelity® Government Money Market Fund, Fidelity® Money Market Fund, and Fidelity® Treasury Only Money Market Fund June 28, 2025 Prospectus**

The following information replaces similar information found in the "Investment Details" section under the "Principal Investment Risks" heading.

In response to market, economic, political, or other conditions, a fund may temporarily use a different investment strategy (including leaving a significant portion of the fund's assets uninvested or, in the case of Fidelity® Treasury Only Money Market Fund, investing in repurchase agreements collateralized by U.S. Treasury obligations) for defensive purposes. Uninvested assets do not earn income for a fund, which may have a significant negative impact on the fund's yield and may prevent the fund from achieving its investment objective. The addition of repurchase agreements could cause a portion of the income from Fidelity® Treasury Only Money Market Fund to be subject to state and local income taxes.

SMF-PSTK-0925-135 1.713587.135 September 22, 2025

**Supplement to the**

**Fidelity® Treasury Digital Fund**

**Liquidity**

**June 28, 2025**

**STATEMENT OF ADDITIONAL INFORMATION**

*The following information replaces similar information found in the "Investment Policies and Limitations" section.*

**<u>Temporary Defensive Policies.</u>** Fidelity® Treasury Digital Fund reserves the right to hold a substantial amount of uninvested cash or invest in repurchase agreements collateralized by U.S. Treasury obligations for temporary, defensive purposes.

TDL-SSTK-0925-100-1.9921586.100 September 22, 2025

**Supplement to the**

**Fidelity® Treasury Digital Fund**

**OnChain**

**July 25, 2025**

**STATEMENT OF ADDITIONAL INFORMATION**

*The following information replaces similar information found in the "Investment Policies and Limitations" section.*

**<u>Temporary Defensive Policies.</u>** Fidelity® Treasury Digital Fund reserves the right to hold a substantial amount of uninvested cash or invest in repurchase agreements collateralized by U.S. Treasury obligations for temporary, defensive purposes.

TDLO-SSTK-0925-100-1.9921587.100 September 22, 2025