# EDGAR Filing Document

**Accession Number:** 0001060517
**File Stem:** 0001410368-26-042925
**Filing Date:** 2026-5
**Character Count:** 17774
**Document Hash:** 774336afebd86c6d1b48c537692c8468
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001410368-26-042925.hdr.sgml**: 20260507

**ACCESSION NUMBER**: 0001410368-26-042925

**CONFORMED SUBMISSION TYPE**: N-MFP3

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20260430

**FILED AS OF DATE**: 20260507

**DATE AS OF CHANGE**: 20260507

**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:** 26952706

**BUSINESS ADDRESS:**
- **STREET 1:** C/O UBS ASSET MANAGEMENT (AMERICAS) LLC
- **STREET 2:** 1285 AVENUE OF THE AMERICAS
- **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:** 1285 AVENUE OF THE AMERICAS
- **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 Preferred Fund (Series ID: S000084283)

| Class ID   | Class Name   | Ticker Symbol   |
|:---|:---|:---|
| C000248580 | Class P      | STAXX           |
| C000250059 | Class T      | SOPXX           |

# 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):** 2026-04-30

**Registrant Full Name:** UBS Series Funds

**CIK Number of Registrant:** 0001060517

**LEI of Registrant:** 54930058UKPXVB81RJ71

**Name of Series:** UBS Select 100% US Treasury Preferred Fund

**LEI of Series:** 529900FTKZBAKZ4ON106

**EDGAR Series Identifier:** S000084283

**Total number of share classes in the series:** 2

**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:** $9247043888.58

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

- **Cash:** $0.00

- **Total Other Assets:** $42587.93

- **Total Liabilities:** $27888695.99

- **Net Assets of Series:** $9219197780.52

- **Number of Shares Outstanding (Series):** 9218998484.5000

- **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 (%)   |
|:---|:---|:---|:---|:---|
| 2026-04-01 | $17883589176.78           | $17883589176.78            | 99.9200%                  | 99.9200%                   |
| 2026-04-02 | $17917479452.71           | $17917479452.71            | 99.9100%                  | 99.9100%                   |
| 2026-04-03 | $0.00                     | $0.00                      | 0.0000%                   | 0.0000%                    |
| 2026-04-06 | $17966031796.31           | $17966031796.31            | 99.9100%                  | 99.9100%                   |
| 2026-04-07 | $17679126391.48           | $17679126391.48            | 99.9100%                  | 99.9100%                   |
| 2026-04-08 | $17697593498.48           | $17697593498.48            | 99.9100%                  | 99.9100%                   |
| 2026-04-09 | $17815143470.01           | $17815143470.01            | 99.9100%                  | 99.9100%                   |
| 2026-04-10 | $17825966178.92           | $17825966178.92            | 99.9100%                  | 99.9100%                   |
| 2026-04-13 | $17685733318.95           | $17685733318.95            | 99.9000%                  | 99.9000%                   |
| 2026-04-14 | $17317754069.39           | $17317754069.39            | 99.9000%                  | 99.9000%                   |
| 2026-04-15 | $17485133616.02           | $17485133616.02            | 99.9100%                  | 99.9100%                   |
| 2026-04-16 | $17410644184.89           | $17410644184.89            | 99.9000%                  | 99.9000%                   |
| 2026-04-17 | $17423698668.60           | $17423698668.60            | 99.9000%                  | 99.9000%                   |
| 2026-04-20 | $17707911949.95           | $17707911949.95            | 99.9000%                  | 99.9000%                   |
| 2026-04-21 | $17385021543.72           | $17385021543.72            | 99.9000%                  | 99.9000%                   |
| 2026-04-22 | $17606474913.96           | $17606474913.96            | 99.9000%                  | 99.9000%                   |
| 2026-04-23 | $17397978068.34           | $17397978068.34            | 99.9000%                  | 99.9000%                   |
| 2026-04-24 | $17489170870.42           | $17489170870.42            | 99.8900%                  | 99.8900%                   |
| 2026-04-27 | $17978017005.53           | $17978017005.53            | 99.9000%                  | 99.9000%                   |
| 2026-04-28 | $17552354181.78           | $17552354181.78            | 99.8900%                  | 99.8900%                   |
| 2026-04-29 | $18522301091.34           | $18522301091.34            | 99.9000%                  | 99.9000%                   |
| 2026-04-30 | $17431760123.21           | $17431760123.21            | 99.9900%                  | 99.9900%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2026-04-01 | 3.7000%             |
| 2026-04-02 | 3.6900%             |
| 2026-04-03 | 0.0000%             |
| 2026-04-06 | 3.6900%             |
| 2026-04-07 | 3.6900%             |
| 2026-04-08 | 3.6900%             |
| 2026-04-09 | 3.6900%             |
| 2026-04-10 | 3.6900%             |
| 2026-04-13 | 3.6900%             |
| 2026-04-14 | 3.6900%             |
| 2026-04-15 | 3.6900%             |
| 2026-04-16 | 3.6900%             |
| 2026-04-17 | 3.6900%             |
| 2026-04-20 | 3.6900%             |
| 2026-04-21 | 3.6900%             |
| 2026-04-22 | 3.6900%             |
| 2026-04-23 | 3.6900%             |
| 2026-04-24 | 3.6900%             |
| 2026-04-27 | 3.6900%             |
| 2026-04-28 | 3.6900%             |
| 2026-04-29 | 3.6900%             |
| 2026-04-30 | 3.6900%             |

### Daily Net Asset Value per Share (Series)
| Date       | Net Asset Value per Share   |
|:---|:---|
| 2026-04-01 | 1.0000                      |
|  |  |
| 2026-04-02 | 1.0000                      |
|  |  |
| 2026-04-03 | 0.0000                      |
|  |  |
| 2026-04-06 | 1.0000                      |
|  |  |
| 2026-04-07 | 1.0000                      |
|  |  |
| 2026-04-08 | 1.0000                      |
|  |  |
| 2026-04-09 | 1.0000                      |
|  |  |
| 2026-04-10 | 1.0000                      |
|  |  |
| 2026-04-13 | 1.0000                      |
|  |  |
| 2026-04-14 | 1.0000                      |
|  |  |
| 2026-04-15 | 1.0000                      |
|  |  |
| 2026-04-16 | 1.0000                      |
|  |  |
| 2026-04-17 | 1.0000                      |
|  |  |
| 2026-04-20 | 1.0000                      |
|  |  |
| 2026-04-21 | 1.0000                      |
|  |  |
| 2026-04-22 | 1.0000                      |
|  |  |
| 2026-04-23 | 1.0000                      |
|  |  |
| 2026-04-24 | 1.0000                      |
|  |  |
| 2026-04-27 | 1.0000                      |
|  |  |
| 2026-04-28 | 1.0000                      |
|  |  |
| 2026-04-29 | 1.0000                      |
|  |  |
| 2026-04-30 | 1.0000                      |
|  |  |

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

### Class: Class P

- **Minimum Initial Investment:** $1.00

- **Net Assets of Class:** $567317518.96

- **Number of Shares Outstanding:** 567304583.0500

- **Expense Reimbursement/Waiver:** 35842.00

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2026-04-01 | 1.0000          |
|  |  |
| 2026-04-02 | 1.0000          |
|  |  |
| 2026-04-03 | 0.0000          |
|  |  |
| 2026-04-06 | 1.0000          |
|  |  |
| 2026-04-07 | 1.0000          |
|  |  |
| 2026-04-08 | 1.0000          |
|  |  |
| 2026-04-09 | 1.0000          |
|  |  |
| 2026-04-10 | 1.0000          |
|  |  |
| 2026-04-13 | 1.0000          |
|  |  |
| 2026-04-14 | 1.0000          |
|  |  |
| 2026-04-15 | 1.0000          |
|  |  |
| 2026-04-16 | 1.0000          |
|  |  |
| 2026-04-17 | 1.0000          |
|  |  |
| 2026-04-20 | 1.0000          |
|  |  |
| 2026-04-21 | 1.0000          |
|  |  |
| 2026-04-22 | 1.0000          |
|  |  |
| 2026-04-23 | 1.0000          |
|  |  |
| 2026-04-24 | 1.0000          |
|  |  |
| 2026-04-27 | 1.0000          |
|  |  |
| 2026-04-28 | 1.0000          |
|  |  |
| 2026-04-29 | 1.0000          |
|  |  |
| 2026-04-30 | 1.0000          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2026-04-01 | $15758661.61              | $4376097.87             |
| 2026-04-02 | $17646355.92              | $9150653.50             |
| 2026-04-03 | $0.00                     | $0.00                   |
| 2026-04-06 | $5416738.50               | $7005237.68             |
| 2026-04-07 | $2015793.23               | $10615908.83            |
| 2026-04-08 | $1560853.56               | $15868437.81            |
| 2026-04-09 | $26257185.91              | $6677512.03             |
| 2026-04-10 | $8218842.10               | $5883591.19             |
| 2026-04-13 | $5162107.58               | $4592336.26             |
| 2026-04-14 | $2445065.39               | $21817768.32            |
| 2026-04-15 | $1820346.61               | $13001660.44            |
| 2026-04-16 | $12169832.09              | $5900300.82             |
| 2026-04-17 | $6781780.12               | $2965931.40             |
| 2026-04-20 | $17741648.74              | $4810915.05             |
| 2026-04-21 | $9689823.52               | $3823770.00             |
| 2026-04-22 | $10119888.93              | $9509788.82             |
| 2026-04-23 | $6448488.44               | $27470372.90            |
| 2026-04-24 | $2904255.62               | $8072966.01             |
| 2026-04-27 | $24195870.27              | $8784758.60             |
| 2026-04-28 | $6201397.81               | $9394374.80             |
| 2026-04-29 | $1817989.55               | $4751307.29             |
| 2026-04-30 | $6630473.38               | $6381624.03             |

**Total Gross Subscriptions (Month):** $191003398.88

**Total Gross Redemptions (Month):** $190855313.65

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2026-04-01 | 3.5600%           |
| 2026-04-02 | 3.5500%           |
| 2026-04-03 | 0.0000%           |
| 2026-04-06 | 3.5500%           |
| 2026-04-07 | 3.5500%           |
| 2026-04-08 | 3.5500%           |
| 2026-04-09 | 3.5500%           |
| 2026-04-10 | 3.5500%           |
| 2026-04-13 | 3.5500%           |
| 2026-04-14 | 3.5500%           |
| 2026-04-15 | 3.5500%           |
| 2026-04-16 | 3.5500%           |
| 2026-04-17 | 3.5500%           |
| 2026-04-20 | 3.5500%           |
| 2026-04-21 | 3.5500%           |
| 2026-04-22 | 3.5500%           |
| 2026-04-23 | 3.5500%           |
| 2026-04-24 | 3.5500%           |
| 2026-04-27 | 3.5500%           |
| 2026-04-28 | 3.5500%           |
| 2026-04-29 | 3.5500%           |
| 2026-04-30 | 3.5500%           |

### Class: Class T

- **Minimum Initial Investment:** $5000000.00

- **Net Assets of Class:** $8651880261.56

- **Number of Shares Outstanding:** 8651693901.4500

- **Expense Reimbursement/Waiver:** 549297.00

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2026-04-01 | 1.0000          |
|  |  |
| 2026-04-02 | 1.0000          |
|  |  |
| 2026-04-03 | 0.0000          |
|  |  |
| 2026-04-06 | 1.0000          |
|  |  |
| 2026-04-07 | 1.0000          |
|  |  |
| 2026-04-08 | 1.0000          |
|  |  |
| 2026-04-09 | 1.0000          |
|  |  |
| 2026-04-10 | 1.0000          |
|  |  |
| 2026-04-13 | 1.0000          |
|  |  |
| 2026-04-14 | 1.0000          |
|  |  |
| 2026-04-15 | 1.0000          |
|  |  |
| 2026-04-16 | 1.0000          |
|  |  |
| 2026-04-17 | 1.0000          |
|  |  |
| 2026-04-20 | 1.0000          |
|  |  |
| 2026-04-21 | 1.0000          |
|  |  |
| 2026-04-22 | 1.0000          |
|  |  |
| 2026-04-23 | 1.0000          |
|  |  |
| 2026-04-24 | 1.0000          |
|  |  |
| 2026-04-27 | 1.0000          |
|  |  |
| 2026-04-28 | 1.0000          |
|  |  |
| 2026-04-29 | 1.0000          |
|  |  |
| 2026-04-30 | 1.0000          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2026-04-01 | $49812020.82              | $20613249.10            |
| 2026-04-02 | $44192713.93              | $34303949.79            |
| 2026-04-03 | $0.00                     | $0.00                   |
| 2026-04-06 | $34165734.88              | $102405969.77           |
| 2026-04-07 | $3984650.28               | $23352944.97            |
| 2026-04-08 | $2892259.20               | $25141712.75            |
| 2026-04-09 | $59210387.74              | $19271815.11            |
| 2026-04-10 | $77795183.44              | $27860449.97            |
| 2026-04-13 | $34862934.97              | $207782458.06           |
| 2026-04-14 | $58883204.71              | $56088222.39            |
| 2026-04-15 | $79376526.96              | $12711787.67            |
| 2026-04-16 | $47516720.02              | $77337597.28            |
| 2026-04-17 | $53081796.03              | $16323027.64            |
| 2026-04-20 | $51785784.34              | $94706982.05            |
| 2026-04-21 | $10806840.33              | $17231231.32            |
| 2026-04-22 | $11733167.21              | $8535526.65             |
| 2026-04-23 | $10927356.76              | $21172243.01            |
| 2026-04-24 | $23457061.78              | $9632494.48             |
| 2026-04-27 | $3380623.25               | $38500857.55            |
| 2026-04-28 | $17040793.24              | $60236953.76            |
| 2026-04-29 | $17451963.03              | $19643678.25            |
| 2026-04-30 | $45210156.03              | $22397125.19            |

**Total Gross Subscriptions (Month):** $737567878.95

**Total Gross Redemptions (Month):** $915250276.76

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2026-04-01 | 3.5600%           |
| 2026-04-02 | 3.5500%           |
| 2026-04-03 | 0.0000%           |
| 2026-04-06 | 3.5500%           |
| 2026-04-07 | 3.5500%           |
| 2026-04-08 | 3.5500%           |
| 2026-04-09 | 3.5500%           |
| 2026-04-10 | 3.5500%           |
| 2026-04-13 | 3.5500%           |
| 2026-04-14 | 3.5500%           |
| 2026-04-15 | 3.5500%           |
| 2026-04-16 | 3.5500%           |
| 2026-04-17 | 3.5500%           |
| 2026-04-20 | 3.5500%           |
| 2026-04-21 | 3.5500%           |
| 2026-04-22 | 3.5500%           |
| 2026-04-23 | 3.5500%           |
| 2026-04-24 | 3.5500%           |
| 2026-04-27 | 3.5500%           |
| 2026-04-28 | 3.5500%           |
| 2026-04-29 | 3.5500%           |
| 2026-04-30 | 3.5500%           |

## 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: 5299000M97HC3J8TJ387
- **C.18 - Value (incl. sponsor support):** $9247043888.58
- **C.18.a - Value (excl. sponsor support):** $9247043888.58
- **C.19 - Percentage of Net Assets:** 100.0000%
- **C.17 - Yield as of Reporting Date:** 0.0000%
- **C.11 - Maturity Date (WAM):** 2026-05-01
- **C.12 - Maturity Date (WAL):** 2026-05-01
- **C.13 - Final Legal Maturity Date:** 2026-05-01
- **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:** 2026-05-07

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

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

**Title of Signing Officer:** Vice President