# EDGAR Filing Document

**Accession Number:** 0001060517
**File Stem:** 0001410368-26-042918
**Filing Date:** 2026-5
**Character Count:** 14357
**Document Hash:** 063bfe7deb58734ebe18bad7ae51844b
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001410368-26-042918.hdr.sgml**: 20260507

**ACCESSION NUMBER**: 0001410368-26-042918

**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:** 26952689

**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 Treasury Preferred Fund (Series ID: S000018677)

| Class ID   | Class Name                         | Ticker Symbol   |
|:---|:---|:---|
| C000051800 | UBS Select Treasury Preferred Fund | STPXX           |

# 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 Treasury Preferred Fund

**LEI of Series:** 549300DXQ8KM8WHPPG39

**EDGAR Series Identifier:** S000018677

**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:** $22726512959.61

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

- **Cash:** $0.00

- **Total Other Assets:** $0.00

- **Total Liabilities:** $64202148.20

- **Net Assets of Series:** $22662310811.41

- **Number of Shares Outstanding (Series):** 22661518559.2800

- **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 | $40613488822.85           | $40613488822.85            | 99.8600%                  | 99.8600%                   |
| 2026-04-02 | $40865037850.10           | $40865037850.10            | 99.8400%                  | 99.8400%                   |
| 2026-04-03 | $0.00                     | $0.00                      | 0.0000%                   | 0.0000%                    |
| 2026-04-06 | $40728519143.42           | $40728519143.42            | 99.8500%                  | 99.8500%                   |
| 2026-04-07 | $41143368214.18           | $41143368214.18            | 99.8500%                  | 99.8500%                   |
| 2026-04-08 | $41597121800.44           | $41597121800.44            | 99.8500%                  | 99.8500%                   |
| 2026-04-09 | $41086501200.20           | $41086501200.20            | 99.8400%                  | 99.8400%                   |
| 2026-04-10 | $41903560730.09           | $41903560730.09            | 99.8300%                  | 99.8300%                   |
| 2026-04-13 | $41265261663.62           | $41265261663.62            | 99.8400%                  | 99.8400%                   |
| 2026-04-14 | $40241554717.18           | $40241554717.18            | 99.8300%                  | 99.8300%                   |
| 2026-04-15 | $40819714686.54           | $40819714686.54            | 99.8400%                  | 99.8400%                   |
| 2026-04-16 | $40526562237.00           | $40526562237.00            | 99.8400%                  | 99.8400%                   |
| 2026-04-17 | $40153261153.00           | $40153261153.00            | 99.8300%                  | 99.8300%                   |
| 2026-04-20 | $41555748289.48           | $41555748289.48            | 99.8400%                  | 99.8400%                   |
| 2026-04-21 | $40220673054.60           | $40220673054.60            | 99.8300%                  | 99.8300%                   |
| 2026-04-22 | $40653283000.62           | $40653283000.62            | 99.8300%                  | 99.8300%                   |
| 2026-04-23 | $39366708404.56           | $39366708404.56            | 99.8200%                  | 99.8200%                   |
| 2026-04-24 | $39360750523.71           | $39360750523.71            | 99.8100%                  | 99.8100%                   |
| 2026-04-27 | $40117075666.04           | $40117075666.04            | 99.8200%                  | 99.8200%                   |
| 2026-04-28 | $40467734414.82           | $40467734414.82            | 99.8200%                  | 99.8200%                   |
| 2026-04-29 | $41131744876.71           | $41131744876.71            | 99.8200%                  | 99.8200%                   |
| 2026-04-30 | $40515233294.55           | $40515233294.55            | 99.9800%                  | 99.9800%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2026-04-01 | 3.7100%             |
| 2026-04-02 | 3.7100%             |
| 2026-04-03 | 0.0000%             |
| 2026-04-06 | 3.7100%             |
| 2026-04-07 | 3.7000%             |
| 2026-04-08 | 3.7000%             |
| 2026-04-09 | 3.7000%             |
| 2026-04-10 | 3.6900%             |
| 2026-04-13 | 3.6900%             |
| 2026-04-14 | 3.6900%             |
| 2026-04-15 | 3.7000%             |
| 2026-04-16 | 3.7000%             |
| 2026-04-17 | 3.7100%             |
| 2026-04-20 | 3.7100%             |
| 2026-04-21 | 3.7100%             |
| 2026-04-22 | 3.7000%             |
| 2026-04-23 | 3.7000%             |
| 2026-04-24 | 3.7100%             |
| 2026-04-27 | 3.7100%             |
| 2026-04-28 | 3.7100%             |
| 2026-04-29 | 3.7100%             |
| 2026-04-30 | 3.7100%             |

### Daily Net Asset Value per Share (Series)
| Date       | Net Asset Value per Share   |
|:---|:---|
| 2026-04-01 | 1.0000                      |
|  |  |
| 2026-04-02 | 1.0001                      |
|  |  |
| 2026-04-03 | 0.0000                      |
|  |  |
| 2026-04-06 | 1.0000                      |
|  |  |
| 2026-04-07 | 1.0001                      |
|  |  |
| 2026-04-08 | 1.0001                      |
|  |  |
| 2026-04-09 | 1.0001                      |
|  |  |
| 2026-04-10 | 1.0001                      |
|  |  |
| 2026-04-13 | 1.0001                      |
|  |  |
| 2026-04-14 | 1.0001                      |
|  |  |
| 2026-04-15 | 1.0001                      |
|  |  |
| 2026-04-16 | 1.0001                      |
|  |  |
| 2026-04-17 | 1.0001                      |
|  |  |
| 2026-04-20 | 1.0001                      |
|  |  |
| 2026-04-21 | 1.0000                      |
|  |  |
| 2026-04-22 | 1.0001                      |
|  |  |
| 2026-04-23 | 1.0000                      |
|  |  |
| 2026-04-24 | 1.0001                      |
|  |  |
| 2026-04-27 | 1.0000                      |
|  |  |
| 2026-04-28 | 1.0001                      |
|  |  |
| 2026-04-29 | 1.0000                      |
|  |  |
| 2026-04-30 | 1.0001                      |
|  |  |

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

### Class: Single Class

- **Minimum Initial Investment:** $50000000.00

- **Net Assets of Class:** $22662310811.41

- **Number of Shares Outstanding:** 22661518559.2800

- **Expense Reimbursement/Waiver:** 733275.56

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2026-04-01 | 1.0000          |
|  |  |
| 2026-04-02 | 1.0001          |
|  |  |
| 2026-04-03 | 0.0000          |
|  |  |
| 2026-04-06 | 1.0000          |
|  |  |
| 2026-04-07 | 1.0001          |
|  |  |
| 2026-04-08 | 1.0001          |
|  |  |
| 2026-04-09 | 1.0001          |
|  |  |
| 2026-04-10 | 1.0001          |
|  |  |
| 2026-04-13 | 1.0001          |
|  |  |
| 2026-04-14 | 1.0001          |
|  |  |
| 2026-04-15 | 1.0001          |
|  |  |
| 2026-04-16 | 1.0001          |
|  |  |
| 2026-04-17 | 1.0001          |
|  |  |
| 2026-04-20 | 1.0001          |
|  |  |
| 2026-04-21 | 1.0000          |
|  |  |
| 2026-04-22 | 1.0001          |
|  |  |
| 2026-04-23 | 1.0000          |
|  |  |
| 2026-04-24 | 1.0001          |
|  |  |
| 2026-04-27 | 1.0000          |
|  |  |
| 2026-04-28 | 1.0001          |
|  |  |
| 2026-04-29 | 1.0000          |
|  |  |
| 2026-04-30 | 1.0001          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2026-04-01 | $267510482.82             | $1021635151.91          |
| 2026-04-02 | $385943232.40             | $145392271.31           |
| 2026-04-03 | $0.00                     | $0.00                   |
| 2026-04-06 | $182533589.25             | $458953184.21           |
| 2026-04-07 | $642386270.80             | $128440252.87           |
| 2026-04-08 | $320973065.84             | $225224775.81           |
| 2026-04-09 | $281425051.29             | $178709593.39           |
| 2026-04-10 | $1034369220.29            | $213252417.92           |
| 2026-04-13 | $145505053.81             | $861006419.22           |
| 2026-04-14 | $216066038.32             | $926169837.73           |
| 2026-04-15 | $815612708.30             | $459997720.47           |
| 2026-04-16 | $370239857.25             | $262018895.84           |
| 2026-04-17 | $320610620.83             | $577798150.71           |
| 2026-04-20 | $1227851261.61            | $262770250.94           |
| 2026-04-21 | $182107493.49             | $1475595556.28          |
| 2026-04-22 | $205998872.31             | $130746262.41           |
| 2026-04-23 | $130202387.35             | $535534161.71           |
| 2026-04-24 | $197129031.96             | $189760313.36           |
| 2026-04-27 | $304377964.79             | $220213286.33           |
| 2026-04-28 | $781877378.88             | $196152554.32           |
| 2026-04-29 | $487717174.20             | $151684641.33           |
| 2026-04-30 | $697760141.52             | $606823182.35           |

**Total Gross Subscriptions (Month):** $9198196897.31

**Total Gross Redemptions (Month):** $9227878880.42

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2026-04-01 | 3.5800%           |
| 2026-04-02 | 3.5700%           |
| 2026-04-03 | 0.0000%           |
| 2026-04-06 | 3.5700%           |
| 2026-04-07 | 3.5600%           |
| 2026-04-08 | 3.5600%           |
| 2026-04-09 | 3.5600%           |
| 2026-04-10 | 3.5500%           |
| 2026-04-13 | 3.5500%           |
| 2026-04-14 | 3.5500%           |
| 2026-04-15 | 3.5600%           |
| 2026-04-16 | 3.5600%           |
| 2026-04-17 | 3.5700%           |
| 2026-04-20 | 3.5700%           |
| 2026-04-21 | 3.5700%           |
| 2026-04-22 | 3.5600%           |
| 2026-04-23 | 3.5600%           |
| 2026-04-24 | 3.5700%           |
| 2026-04-27 | 3.5700%           |
| 2026-04-28 | 3.5700%           |
| 2026-04-29 | 3.5700%           |
| 2026-04-30 | 3.5700%           |

**Beneficial/Record Owner Categories**
| Category                  | Other Category   | Record Owner %   | Beneficial Owner %   |
|:---|:---|:---|:---|
| Non-financial corporation |  | 10.0600%         | 0.0000%              |
| Broker-dealer             |  | 7.2800%          | 0.0000%              |
| Other                     | IND FID AS EXEC  | 7.2900%          | 0.0000%              |

## Part C: Schedule of Portfolio Securities

### Security 1: Treasury Master Fund

- **C.1 - Title:** Treasury Master Fund
- **C.6 - Investment Category:** Investment Company
- **Identifiers:** C.3 - CUSIP: 81699K911, C.3 - LEI: 549300XQ6V293JKF0677, C.5 - Other ID: 81699K911
- **C.18 - Value (incl. sponsor support):** $22726512959.61
- **C.18.a - Value (excl. sponsor support):** $22726512959.61
- **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