# EDGAR Filing Document

**Accession Number:** 0001060517
**File Stem:** 0001410368-26-034965
**Filing Date:** 2026-4
**Character Count:** 14359
**Document Hash:** 9dafd413a2321642acaf9349e9088eb3
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001410368-26-034965.hdr.sgml**: 20260407

**ACCESSION NUMBER**: 0001410368-26-034965

**CONFORMED SUBMISSION TYPE**: N-MFP3

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20260331

**FILED AS OF DATE**: 20260407

**DATE AS OF CHANGE**: 20260407

**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:** 26843741

**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):** 2026-03-31

**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:** $22761829321.19

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

- **Cash:** $0.00

- **Total Other Assets:** $0.00

- **Total Liabilities:** $69836526.70

- **Net Assets of Series:** $22691992794.49

- **Number of Shares Outstanding (Series):** 22691200542.3900

- **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 (%)   |
|:---|:---|:---|:---|:---|
| 2026-03-02 | $42589274985.29           | $42589274985.29            | 99.8800%                  | 99.8800%                   |
| 2026-03-03 | $43010424814.43           | $43010424814.43            | 99.8800%                  | 99.8800%                   |
| 2026-03-04 | $43037766417.32           | $43037766417.32            | 99.8800%                  | 99.8800%                   |
| 2026-03-05 | $42304103741.75           | $42304103741.75            | 99.8800%                  | 99.8800%                   |
| 2026-03-06 | $42862670782.66           | $42862670782.66            | 99.8700%                  | 99.8700%                   |
| 2026-03-09 | $43779474788.47           | $43779474788.47            | 99.8800%                  | 99.8800%                   |
| 2026-03-10 | $43469339891.03           | $43469339891.03            | 99.8700%                  | 99.8700%                   |
| 2026-03-11 | $43322214538.44           | $43322214538.44            | 99.8700%                  | 99.8700%                   |
| 2026-03-12 | $42175818525.78           | $42175818525.78            | 99.8700%                  | 99.8700%                   |
| 2026-03-13 | $42228238288.19           | $42228238288.19            | 99.8500%                  | 99.8500%                   |
| 2026-03-16 | $41972716179.20           | $41972716179.20            | 99.8700%                  | 99.8700%                   |
| 2026-03-17 | $42136464908.37           | $42136464908.37            | 99.8700%                  | 99.8700%                   |
| 2026-03-18 | $42768262665.51           | $42768262665.51            | 99.8700%                  | 99.8700%                   |
| 2026-03-19 | $42072003582.63           | $42072003582.63            | 99.8600%                  | 99.8600%                   |
| 2026-03-20 | $41909309451.03           | $41909309451.03            | 99.8500%                  | 99.8500%                   |
| 2026-03-23 | $43227765953.06           | $43227765953.06            | 99.8600%                  | 99.8600%                   |
| 2026-03-24 | $42718674187.47           | $42718674187.47            | 99.8600%                  | 99.8600%                   |
| 2026-03-25 | $42754654411.77           | $42754654411.77            | 99.8600%                  | 99.8600%                   |
| 2026-03-26 | $41308187325.77           | $41308187325.77            | 99.8500%                  | 99.8500%                   |
| 2026-03-27 | $41237547999.68           | $41237547999.68            | 99.8300%                  | 99.8300%                   |
| 2026-03-30 | $41727410094.29           | $41727410094.29            | 99.8400%                  | 99.8400%                   |
| 2026-03-31 | $41136618595.38           | $41136618595.38            | 99.8600%                  | 99.8600%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2026-03-02 | 3.7400%             |
| 2026-03-03 | 3.7400%             |
| 2026-03-04 | 3.7400%             |
| 2026-03-05 | 3.7300%             |
| 2026-03-06 | 3.7200%             |
| 2026-03-09 | 3.7200%             |
| 2026-03-10 | 3.7200%             |
| 2026-03-11 | 3.7100%             |
| 2026-03-12 | 3.7100%             |
| 2026-03-13 | 3.7100%             |
| 2026-03-16 | 3.7100%             |
| 2026-03-17 | 3.7100%             |
| 2026-03-18 | 3.7100%             |
| 2026-03-19 | 3.7100%             |
| 2026-03-20 | 3.7100%             |
| 2026-03-23 | 3.7100%             |
| 2026-03-24 | 3.7100%             |
| 2026-03-25 | 3.7100%             |
| 2026-03-26 | 3.7100%             |
| 2026-03-27 | 3.7100%             |
| 2026-03-30 | 3.7200%             |
| 2026-03-31 | 3.7200%             |

### Daily Net Asset Value per Share (Series)
| Date       | Net Asset Value per Share   |
|:---|:---|
| 2026-03-02 | 1.0001                      |
|  |  |
| 2026-03-03 | 1.0001                      |
|  |  |
| 2026-03-04 | 1.0001                      |
|  |  |
| 2026-03-05 | 1.0001                      |
|  |  |
| 2026-03-06 | 1.0001                      |
|  |  |
| 2026-03-09 | 1.0001                      |
|  |  |
| 2026-03-10 | 1.0001                      |
|  |  |
| 2026-03-11 | 1.0001                      |
|  |  |
| 2026-03-12 | 1.0001                      |
|  |  |
| 2026-03-13 | 1.0001                      |
|  |  |
| 2026-03-16 | 1.0001                      |
|  |  |
| 2026-03-17 | 1.0001                      |
|  |  |
| 2026-03-18 | 1.0001                      |
|  |  |
| 2026-03-19 | 1.0001                      |
|  |  |
| 2026-03-20 | 1.0000                      |
|  |  |
| 2026-03-23 | 1.0000                      |
|  |  |
| 2026-03-24 | 1.0000                      |
|  |  |
| 2026-03-25 | 1.0001                      |
|  |  |
| 2026-03-26 | 1.0000                      |
|  |  |
| 2026-03-27 | 1.0001                      |
|  |  |
| 2026-03-30 | 1.0001                      |
|  |  |
| 2026-03-31 | 1.0001                      |
|  |  |

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

### Class: Single Class

- **Minimum Initial Investment:** $50000000.00

- **Net Assets of Class:** $22691992794.49

- **Number of Shares Outstanding:** 22691200542.3900

- **Expense Reimbursement/Waiver:** 768498.14

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2026-03-02 | 1.0001          |
|  |  |
| 2026-03-03 | 1.0001          |
|  |  |
| 2026-03-04 | 1.0001          |
|  |  |
| 2026-03-05 | 1.0001          |
|  |  |
| 2026-03-06 | 1.0001          |
|  |  |
| 2026-03-09 | 1.0001          |
|  |  |
| 2026-03-10 | 1.0001          |
|  |  |
| 2026-03-11 | 1.0001          |
|  |  |
| 2026-03-12 | 1.0001          |
|  |  |
| 2026-03-13 | 1.0001          |
|  |  |
| 2026-03-16 | 1.0001          |
|  |  |
| 2026-03-17 | 1.0001          |
|  |  |
| 2026-03-18 | 1.0001          |
|  |  |
| 2026-03-19 | 1.0001          |
|  |  |
| 2026-03-20 | 1.0000          |
|  |  |
| 2026-03-23 | 1.0000          |
|  |  |
| 2026-03-24 | 1.0000          |
|  |  |
| 2026-03-25 | 1.0001          |
|  |  |
| 2026-03-26 | 1.0000          |
|  |  |
| 2026-03-27 | 1.0001          |
|  |  |
| 2026-03-30 | 1.0001          |
|  |  |
| 2026-03-31 | 1.0001          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2026-03-02 | $694879430.61             | $477479348.79           |
| 2026-03-03 | $308903078.41             | $163071296.38           |
| 2026-03-04 | $83757576.68              | $463337894.40           |
| 2026-03-05 | $398442035.58             | $304882790.52           |
| 2026-03-06 | $948166424.53             | $375108767.81           |
| 2026-03-09 | $867687254.10             | $347462089.96           |
| 2026-03-10 | $397963427.06             | $488593322.85           |
| 2026-03-11 | $389888040.91             | $819938377.91           |
| 2026-03-12 | $637404372.23             | $896505508.37           |
| 2026-03-13 | $625482413.76             | $497310433.52           |
| 2026-03-16 | $63603900.10              | $630601230.19           |
| 2026-03-17 | $514215171.24             | $231722944.91           |
| 2026-03-18 | $927320706.07             | $609494798.78           |
| 2026-03-19 | $352781683.52             | $382913545.61           |
| 2026-03-20 | $683052184.32             | $822872445.36           |
| 2026-03-23 | $890706637.63             | $202463758.59           |
| 2026-03-24 | $465977629.88             | $572795316.95           |
| 2026-03-25 | $376174526.34             | $739099434.15           |
| 2026-03-26 | $91351570.99              | $845755460.01           |
| 2026-03-27 | $599423675.44             | $581730584.68           |
| 2026-03-30 | $492533857.68             | $387732880.58           |
| 2026-03-31 | $631912668.83             | $942832747.69           |

**Total Gross Subscriptions (Month):** $11441628265.91

**Total Gross Redemptions (Month):** $11783704978.01

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2026-03-02 | 3.6000%           |
| 2026-03-03 | 3.6000%           |
| 2026-03-04 | 3.6000%           |
| 2026-03-05 | 3.5900%           |
| 2026-03-06 | 3.5800%           |
| 2026-03-09 | 3.5800%           |
| 2026-03-10 | 3.5800%           |
| 2026-03-11 | 3.5700%           |
| 2026-03-12 | 3.5700%           |
| 2026-03-13 | 3.5700%           |
| 2026-03-16 | 3.5700%           |
| 2026-03-17 | 3.5700%           |
| 2026-03-18 | 3.5700%           |
| 2026-03-19 | 3.5700%           |
| 2026-03-20 | 3.5700%           |
| 2026-03-23 | 3.5700%           |
| 2026-03-24 | 3.5700%           |
| 2026-03-25 | 3.5700%           |
| 2026-03-26 | 3.5700%           |
| 2026-03-27 | 3.5700%           |
| 2026-03-30 | 3.5800%           |
| 2026-03-31 | 3.5800%           |

**Beneficial/Record Owner Categories**
| Category                  | Other Category   | Record Owner %   | Beneficial Owner %   |
|:---|:---|:---|:---|
| Non-financial corporation |  | 5.6800%          | 0.0000%              |
| Broker-dealer             |  | 7.3500%          | 0.0000%              |
| Other                     | IND FID AS EXEC  | 6.2400%          | 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):** $22761829321.19
- **C.18.a - Value (excl. sponsor support):** $22761829321.19
- **C.19 - Percentage of Net Assets:** 100.0000%
- **C.17 - Yield as of Reporting Date:** 0.0000%
- **C.11 - Maturity Date (WAM):** 2026-04-01
- **C.12 - Maturity Date (WAL):** 2026-04-01
- **C.13 - Final Legal Maturity Date:** 2026-04-01
- **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:** 2026-04-07

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

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

**Title of Signing Officer:** Vice President