# EDGAR Filing Document

**Accession Number:** 0001060517
**File Stem:** 0001145549-25-038888
**Filing Date:** 2025-6
**Character Count:** 13628
**Document Hash:** d368d9cccfae9ddeae0a48322b071084
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001145549-25-038888.hdr.sgml**: 20250606

**ACCESSION NUMBER**: 0001145549-25-038888

**CONFORMED SUBMISSION TYPE**: N-MFP3

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20250531

**FILED AS OF DATE**: 20250606

**DATE AS OF CHANGE**: 20250606

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** UBS Series Funds
- **CENTRAL INDEX KEY:** 0001060517

**ORGANIZATION NAME:**
- **EIN:** 134010447
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 0430

**FILING VALUES:**
- **FORM TYPE:** N-MFP3
- **SEC ACT:** 1940 Act
- **SEC FILE NUMBER:** 811-08767
- **FILM NUMBER:** 251029856

**BUSINESS ADDRESS:**
- **STREET 1:** C/O UBS ASSET MANAGEMENT (AMERICAS) LLC
- **STREET 2:** 787 SEVENTH AVENUE
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10019
- **BUSINESS PHONE:** 212-821-3000

**MAIL ADDRESS:**
- **STREET 1:** C/O UBS ASSET MANAGEMENT (AMERICAS) LLC
- **STREET 2:** 787 SEVENTH AVENUE
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10019

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** UBS MONEY SERIES
- **DATE OF NAME CHANGE:** 20020716

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** BRINSON MONEY SERIES
- **DATE OF NAME CHANGE:** 20010625

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** MITCHELL HUTCHINS LIR MONEY SERIES
- **DATE OF NAME CHANGE:** 19990730

## Series and Classes Contracts Data

### UBS Select 100% US Treasury Institutional Fund (Series ID: S000084282)

| Class ID   | Class Name                                     | Ticker Symbol   |
|:---|:---|:---|
| C000248579 | UBS Select 100% US Treasury Institutional Fund | SIOXX           |

# Form N-MFP3: Monthly Schedule of Portfolio Holdings

## N-MFP: Filer Information
**Submission Type:** N-MFP3
**CIK:** 0001060517

### General Information

**Report for (YYYY-MM-DD):** 2025-05-31

**Registrant Full Name:** UBS Series Funds

**CIK Number of Registrant:** 0001060517

**LEI of Registrant:** 54930058UKPXVB81RJ71

**Name of Series:** 100% US Treasury Institutional Fund

**LEI of Series:** 529900KWG787B4G5P791

**EDGAR Series Identifier:** S000084282

**Total number of share classes in the series:** 1

**Is this the fund's final filing on Form N-MFP?:** No

**Has the fund acquired or merged with another fund?:** No

## Part A: Series-Level Information about the Fund

### Service Providers
| Role                          | Details                                                      | File/CIK Number   |
|:---|:---|:---|
| Investment Adviser            | UBS ASSET MANAGEMENT (AMERICAS) LLC                          | 801-34910         |
| Independent Public Accountant | Ernst & Young  LLP<br>City: New York<br>State: NY            |  |
| Administrator                 | UBS ASSET MANAGEMENT (AMERICAS) LLC                          |  |
| Transfer Agent                | BNY Mellon Investment Servicing (US) Inc.<br>CIK: 0000849542 | 084-01761         |

### Fund Characteristics & Assets

- **Securities Act File Number:** 333-52965

- **Is this a Feeder Fund?:** Yes

- **Is this a Master Fund?:** No

- **Is this series for insurance company separate accounts?:** No

- **Money Market Fund Category:** Government

- **Is this a Retail Money Market Fund?:** No

- **Is this a Government Money Market Fund?:** Yes

- **WAM:** 1 days

- **WAL:** 1 days

- **Total Value of Portfolio Securities:** $6766472372.52

- **Amortized Cost of Portfolio Securities:** $0.00

- **Cash:** $0.00

- **Total Other Assets:** $60786.96

- **Total Liabilities:** $25147186.00

- **Net Assets of Series:** $6741385973.48

- **Number of Shares Outstanding (Series):** 6741307105.3600

- **Does the fund seek to maintain a stable price per share?:** Yes

- **Stable Price Per Share:** $1.00

- **Is cash management vehicle an affiliated fund?:** No

- **Does the fund apply liquidity fees?:** No

### Daily & Weekly Liquid Assets
| Date       | Daily Liquid Assets ($)   | Weekly Liquid Assets ($)   | Daily Liquid Assets (%)   | Weekly Liquid Assets (%)   |
|:---|:---|:---|:---|:---|
| 2025-05-01 | $9996166137.91            | $9996166137.91             | 99.9800%                  | 99.9800%                   |
| 2025-05-02 | $9997744267.98            | $9997744267.98             | 99.9700%                  | 99.9700%                   |
| 2025-05-05 | $10098751145.96           | $10098751145.96            | 99.9700%                  | 99.9700%                   |
| 2025-05-06 | $10186020630.95           | $10186020630.95            | 99.9700%                  | 99.9700%                   |
| 2025-05-07 | $10535209970.67           | $10535209970.67            | 99.9700%                  | 99.9700%                   |
| 2025-05-08 | $10208357103.82           | $10208357103.82            | 99.9600%                  | 99.9600%                   |
| 2025-05-09 | $10254820704.66           | $10254820704.66            | 99.9600%                  | 99.9600%                   |
| 2025-05-12 | $10637702256.41           | $10637702256.41            | 99.9500%                  | 99.9500%                   |
| 2025-05-13 | $10216377671.67           | $10216377671.67            | 99.9400%                  | 99.9400%                   |
| 2025-05-14 | $10767973866.92           | $10767973866.92            | 99.9400%                  | 99.9400%                   |
| 2025-05-15 | $10462816280.22           | $10462816280.22            | 99.9400%                  | 99.9400%                   |
| 2025-05-16 | $10442715481.03           | $10442715481.03            | 99.9300%                  | 99.9300%                   |
| 2025-05-19 | $10960210680.94           | $10960210680.94            | 99.9300%                  | 99.9300%                   |
| 2025-05-20 | $10353231652.25           | $10353231652.25            | 99.9300%                  | 99.9300%                   |
| 2025-05-21 | $10935188677.45           | $10935188677.45            | 99.9300%                  | 99.9300%                   |
| 2025-05-22 | $10526384890.20           | $10526384890.20            | 99.9200%                  | 99.9200%                   |
| 2025-05-23 | $11048384155.29           | $11048384155.29            | 99.9200%                  | 99.9200%                   |
| 2025-05-27 | $10514986011.13           | $10514986011.13            | 99.9100%                  | 99.9100%                   |
| 2025-05-28 | $11221302822.79           | $11221302822.79            | 99.9100%                  | 99.9100%                   |
| 2025-05-29 | $10699003284.12           | $10699003284.12            | 99.9100%                  | 99.9100%                   |
| 2025-05-30 | $10766730553.02           | $10766730553.02            | 99.9000%                  | 99.9000%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2025-05-01 | 4.3200%             |
| 2025-05-02 | 4.3200%             |
| 2025-05-05 | 4.3200%             |
| 2025-05-06 | 4.3200%             |
| 2025-05-07 | 4.3200%             |
| 2025-05-08 | 4.3200%             |
| 2025-05-09 | 4.3200%             |
| 2025-05-12 | 4.3200%             |
| 2025-05-13 | 4.3200%             |
| 2025-05-14 | 4.3200%             |
| 2025-05-15 | 4.3200%             |
| 2025-05-16 | 4.3300%             |
| 2025-05-19 | 4.3300%             |
| 2025-05-20 | 4.3300%             |
| 2025-05-21 | 4.3300%             |
| 2025-05-22 | 4.3300%             |
| 2025-05-23 | 4.3300%             |
| 2025-05-27 | 4.3300%             |
| 2025-05-28 | 4.3300%             |
| 2025-05-29 | 4.3300%             |
| 2025-05-30 | 4.3300%             |

### Daily Net Asset Value per Share (Series)
| Date       | Net Asset Value per Share   |
|:---|:---|
| 2025-05-01 | 1.0000                      |
|  |  |
| 2025-05-02 | 1.0001                      |
|  |  |
| 2025-05-05 | 1.0000                      |
|  |  |
| 2025-05-06 | 1.0001                      |
|  |  |
| 2025-05-07 | 1.0001                      |
|  |  |
| 2025-05-08 | 1.0001                      |
|  |  |
| 2025-05-09 | 1.0001                      |
|  |  |
| 2025-05-12 | 1.0001                      |
|  |  |
| 2025-05-13 | 1.0001                      |
|  |  |
| 2025-05-14 | 1.0000                      |
|  |  |
| 2025-05-15 | 1.0001                      |
|  |  |
| 2025-05-16 | 1.0000                      |
|  |  |
| 2025-05-19 | 1.0001                      |
|  |  |
| 2025-05-20 | 1.0001                      |
|  |  |
| 2025-05-21 | 1.0001                      |
|  |  |
| 2025-05-22 | 1.0001                      |
|  |  |
| 2025-05-23 | 1.0001                      |
|  |  |
| 2025-05-27 | 1.0001                      |
|  |  |
| 2025-05-28 | 1.0001                      |
|  |  |
| 2025-05-29 | 1.0001                      |
|  |  |
| 2025-05-30 | 1.0001                      |
|  |  |

## Part B: Class-Level Information about the Fund

### Class: Single Class

- **Minimum Initial Investment:** $1.00

- **Net Assets of Class:** $6741385973.48

- **Number of Shares Outstanding:** 6741307105.3600

- **Expense Reimbursement/Waiver:** 165170.00

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2025-05-01 | 1.0000          |
|  |  |
| 2025-05-02 | 1.0001          |
|  |  |
| 2025-05-05 | 1.0000          |
|  |  |
| 2025-05-06 | 1.0001          |
|  |  |
| 2025-05-07 | 1.0001          |
|  |  |
| 2025-05-08 | 1.0001          |
|  |  |
| 2025-05-09 | 1.0001          |
|  |  |
| 2025-05-12 | 1.0001          |
|  |  |
| 2025-05-13 | 1.0001          |
|  |  |
| 2025-05-14 | 1.0000          |
|  |  |
| 2025-05-15 | 1.0001          |
|  |  |
| 2025-05-16 | 1.0000          |
|  |  |
| 2025-05-19 | 1.0001          |
|  |  |
| 2025-05-20 | 1.0001          |
|  |  |
| 2025-05-21 | 1.0001          |
|  |  |
| 2025-05-22 | 1.0001          |
|  |  |
| 2025-05-23 | 1.0001          |
|  |  |
| 2025-05-27 | 1.0001          |
|  |  |
| 2025-05-28 | 1.0001          |
|  |  |
| 2025-05-29 | 1.0001          |
|  |  |
| 2025-05-30 | 1.0001          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2025-05-01 | $75800861.16              | $26990631.81            |
| 2025-05-02 | $63067331.31              | $21268908.60            |
| 2025-05-05 | $75685407.94              | $37840384.02            |
| 2025-05-06 | $54841240.80              | $31487409.30            |
| 2025-05-07 | $48523637.63              | $25981700.64            |
| 2025-05-08 | $54989590.18              | $42829689.00            |
| 2025-05-09 | $45201105.74              | $19702196.33            |
| 2025-05-12 | $35814498.72              | $47096822.89            |
| 2025-05-13 | $73169625.70              | $85204320.98            |
| 2025-05-14 | $102327101.66             | $48021206.42            |
| 2025-05-15 | $62879501.28              | $51062946.50            |
| 2025-05-16 | $61103387.62              | $94534800.61            |
| 2025-05-19 | $48210814.13              | $24743263.16            |
| 2025-05-20 | $80223817.80              | $44789416.06            |
| 2025-05-21 | $73146359.71              | $29791697.41            |
| 2025-05-22 | $55694640.75              | $73261472.27            |
| 2025-05-23 | $28632004.91              | $24243364.81            |
| 2025-05-27 | $62158031.79              | $55393585.13            |
| 2025-05-28 | $45246852.83              | $42366884.54            |
| 2025-05-29 | $45382128.63              | $39917939.72            |
| 2025-05-30 | $95733835.03              | $27571162.24            |

**Total Gross Subscriptions (Month):** $1287831775.32

**Total Gross Redemptions (Month):** $894099802.44

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2025-05-01 | 4.1400%           |
| 2025-05-02 | 4.1400%           |
| 2025-05-05 | 4.1400%           |
| 2025-05-06 | 4.1400%           |
| 2025-05-07 | 4.1400%           |
| 2025-05-08 | 4.1400%           |
| 2025-05-09 | 4.1400%           |
| 2025-05-12 | 4.1400%           |
| 2025-05-13 | 4.1400%           |
| 2025-05-14 | 4.1400%           |
| 2025-05-15 | 4.1400%           |
| 2025-05-16 | 4.1500%           |
| 2025-05-19 | 4.1500%           |
| 2025-05-20 | 4.1500%           |
| 2025-05-21 | 4.1500%           |
| 2025-05-22 | 4.1500%           |
| 2025-05-23 | 4.1500%           |
| 2025-05-27 | 4.1500%           |
| 2025-05-28 | 4.1500%           |
| 2025-05-29 | 4.1500%           |
| 2025-05-30 | 4.1500%           |

## Part C: Schedule of Portfolio Securities

### Security 1: 100 [percent symbol] US Treasury Master Fund

- **C.1 - Title:** 100 [percent symbol] US Treasury Master Fund
- **C.6 - Investment Category:** Investment Company
- **Identifiers:** C.3 - CUSIP: 902656883, C.3 - LEI: 549300EBIIAXTNCMYQ69
- **C.18 - Value (incl. sponsor support):** $6766472372.52
- **C.18.a - Value (excl. sponsor support):** $6766472372.52
- **C.19 - Percentage of Net Assets:** 100.0000%
- **C.17 - Yield as of Reporting Date:** 0.0000%
- **C.11 - Maturity Date (WAM):** 2025-06-02
- **C.12 - Maturity Date (WAL):** 2025-06-02
- **C.13 - Final Legal Maturity Date:** 2025-06-02
- **Characteristics:** C.9 Eligible Security? Yes, C.14 Has Demand Feature? No, C.15 Has Guarantee? No, C.16 Has Enhancement? No, C.22 Is an Illiquid Security? No, C.20 Is a Daily Liquid Asset? Yes, C.21 Is a Weekly Liquid Asset? Yes, C.23 Categorized at Level 3? No

## N-MFP: Signatures

**Registrant:** UBS Series Funds

**Date:** 2025-06-06

**By:** /s/Rose Ann Bubloski

**Name of Signing Officer:** Rose Ann Bubloski

**Title of Signing Officer:** Vice President