# EDGAR Filing Document

**Accession Number:** 0001060517
**File Stem:** 0001410368-26-000465
**Filing Date:** 2026-1
**Character Count:** 14159
**Document Hash:** f5e1c1ff1b8ba07e681b826ee71f023c
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001410368-26-000465.hdr.sgml**: 20260108

**ACCESSION NUMBER**: 0001410368-26-000465

**CONFORMED SUBMISSION TYPE**: N-MFP3

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20251231

**FILED AS OF DATE**: 20260108

**DATE AS OF CHANGE**: 20260108

**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:** 26520423

**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 Institutional Fund (Series ID: S000002682)

| Class ID   | Class Name                             | Ticker Symbol   |
|:---|:---|:---|
| C000007334 | UBS Select Treasury Institutional Fund | SETXX           |

# 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):** 2025-12-31

**Registrant Full Name:** UBS Series Funds

**CIK Number of Registrant:** 0001060517

**LEI of Registrant:** 54930058UKPXVB81RJ71

**Name of Series:** UBS Select Treasury Institutional Fund

**LEI of Series:** 549300OA0OSRYE6ZYO90

**EDGAR Series Identifier:** S000002682

**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:** $18824683706.70

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

- **Cash:** $0.00

- **Total Other Assets:** $0.00

- **Total Liabilities:** $61417996.14

- **Net Assets of Series:** $18763265710.56

- **Number of Shares Outstanding (Series):** 18763164244.9900

- **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 (%)   |
|:---|:---|:---|:---|:---|
| 2025-12-01 | $41865978251.56           | $42865978251.56            | 97.5400%                  | 99.8700%                   |
| 2025-12-02 | $41931763914.22           | $42931763914.22            | 97.5400%                  | 99.8700%                   |
| 2025-12-03 | $42231647044.52           | $43231647044.52            | 97.5600%                  | 99.8700%                   |
| 2025-12-04 | $41189999354.99           | $42189999354.99            | 97.4900%                  | 99.8600%                   |
| 2025-12-05 | $41400493300.61           | $42400493300.61            | 97.4900%                  | 99.8500%                   |
| 2025-12-08 | $42369468672.36           | $43369468672.36            | 97.5500%                  | 99.8500%                   |
| 2025-12-09 | $42043837519.16           | $43043837519.16            | 97.5300%                  | 99.8500%                   |
| 2025-12-10 | $43533768607.49           | $43533768607.49            | 99.8500%                  | 99.8500%                   |
| 2025-12-11 | $42471226330.20           | $42471226330.20            | 99.8500%                  | 99.8500%                   |
| 2025-12-12 | $41980459026.43           | $41980459026.43            | 99.8300%                  | 99.8300%                   |
| 2025-12-15 | $41897548549.75           | $41897548549.75            | 99.8400%                  | 99.8400%                   |
| 2025-12-16 | $42052508103.61           | $42052508103.61            | 99.8400%                  | 99.8400%                   |
| 2025-12-17 | $42346709757.10           | $42346709757.10            | 99.8400%                  | 99.8400%                   |
| 2025-12-18 | $41215093458.97           | $41215093458.97            | 99.8300%                  | 99.8300%                   |
| 2025-12-19 | $41429549983.33           | $41429549983.33            | 99.8100%                  | 99.8100%                   |
| 2025-12-22 | $41831569526.91           | $41831569526.91            | 99.8200%                  | 99.8200%                   |
| 2025-12-23 | $42127264479.44           | $42127264479.44            | 99.8200%                  | 99.8200%                   |
| 2025-12-24 | $42636277285.30           | $42636277285.30            | 99.8100%                  | 99.8100%                   |
| 2025-12-26 | $42494306617.08           | $42494306617.08            | 99.8000%                  | 99.8000%                   |
| 2025-12-29 | $42668089192.29           | $42668089192.29            | 99.8000%                  | 99.8000%                   |
| 2025-12-30 | $41957640744.42           | $41957640744.42            | 99.8000%                  | 99.8000%                   |
| 2025-12-31 | $42427372114.32           | $42427372114.32            | 99.7900%                  | 99.7900%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2025-12-01 | 4.0300%             |
| 2025-12-02 | 4.0300%             |
| 2025-12-03 | 4.0200%             |
| 2025-12-04 | 4.0100%             |
| 2025-12-05 | 3.9700%             |
| 2025-12-08 | 3.9700%             |
| 2025-12-09 | 3.9600%             |
| 2025-12-10 | 3.9600%             |
| 2025-12-11 | 3.9400%             |
| 2025-12-12 | 3.8900%             |
| 2025-12-15 | 3.8800%             |
| 2025-12-16 | 3.8600%             |
| 2025-12-17 | 3.8500%             |
| 2025-12-18 | 3.8500%             |
| 2025-12-19 | 3.8300%             |
| 2025-12-22 | 3.8300%             |
| 2025-12-23 | 3.8300%             |
| 2025-12-24 | 3.8200%             |
| 2025-12-26 | 3.8300%             |
| 2025-12-29 | 3.8400%             |
| 2025-12-30 | 3.8400%             |
| 2025-12-31 | 3.8500%             |

### Daily Net Asset Value per Share (Series)
| Date       | Net Asset Value per Share   |
|:---|:---|
| 2025-12-01 | 1.0001                      |
|  |  |
| 2025-12-02 | 1.0002                      |
|  |  |
| 2025-12-03 | 1.0002                      |
|  |  |
| 2025-12-04 | 1.0002                      |
|  |  |
| 2025-12-05 | 1.0002                      |
|  |  |
| 2025-12-08 | 1.0002                      |
|  |  |
| 2025-12-09 | 1.0002                      |
|  |  |
| 2025-12-10 | 1.0003                      |
|  |  |
| 2025-12-11 | 1.0003                      |
|  |  |
| 2025-12-12 | 1.0003                      |
|  |  |
| 2025-12-15 | 1.0003                      |
|  |  |
| 2025-12-16 | 1.0003                      |
|  |  |
| 2025-12-17 | 1.0003                      |
|  |  |
| 2025-12-18 | 1.0003                      |
|  |  |
| 2025-12-19 | 1.0003                      |
|  |  |
| 2025-12-22 | 1.0003                      |
|  |  |
| 2025-12-23 | 1.0003                      |
|  |  |
| 2025-12-24 | 1.0003                      |
|  |  |
| 2025-12-26 | 1.0003                      |
|  |  |
| 2025-12-29 | 1.0003                      |
|  |  |
| 2025-12-30 | 1.0003                      |
|  |  |
| 2025-12-31 | 1.0002                      |
|  |  |

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

### Class: Single Class

- **Minimum Initial Investment:** $1000000.00

- **Net Assets of Class:** $18763265710.56

- **Number of Shares Outstanding:** 18763164244.9900

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2025-12-01 | 1.0001          |
|  |  |
| 2025-12-02 | 1.0002          |
|  |  |
| 2025-12-03 | 1.0002          |
|  |  |
| 2025-12-04 | 1.0002          |
|  |  |
| 2025-12-05 | 1.0002          |
|  |  |
| 2025-12-08 | 1.0002          |
|  |  |
| 2025-12-09 | 1.0002          |
|  |  |
| 2025-12-10 | 1.0003          |
|  |  |
| 2025-12-11 | 1.0003          |
|  |  |
| 2025-12-12 | 1.0003          |
|  |  |
| 2025-12-15 | 1.0003          |
|  |  |
| 2025-12-16 | 1.0003          |
|  |  |
| 2025-12-17 | 1.0003          |
|  |  |
| 2025-12-18 | 1.0003          |
|  |  |
| 2025-12-19 | 1.0003          |
|  |  |
| 2025-12-22 | 1.0003          |
|  |  |
| 2025-12-23 | 1.0003          |
|  |  |
| 2025-12-24 | 1.0003          |
|  |  |
| 2025-12-26 | 1.0003          |
|  |  |
| 2025-12-29 | 1.0003          |
|  |  |
| 2025-12-30 | 1.0003          |
|  |  |
| 2025-12-31 | 1.0002          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2025-12-01 | $493418591.17             | $92793123.62            |
| 2025-12-02 | $119516851.62             | $221047640.91           |
| 2025-12-03 | $114677945.97             | $200999678.39           |
| 2025-12-04 | $113507017.24             | $135827194.75           |
| 2025-12-05 | $259599408.96             | $102282876.59           |
| 2025-12-08 | $89153905.39              | $217809614.69           |
| 2025-12-09 | $170407097.19             | $164382475.39           |
| 2025-12-10 | $244751944.20             | $130049299.28           |
| 2025-12-11 | $71618336.16              | $316763298.04           |
| 2025-12-12 | $106643723.14             | $190008270.19           |
| 2025-12-15 | $493485901.58             | $129668206.52           |
| 2025-12-16 | $260223905.00             | $165238596.88           |
| 2025-12-17 | $133283765.32             | $266112566.10           |
| 2025-12-18 | $177244481.39             | $125788211.76           |
| 2025-12-19 | $247455717.64             | $157781155.62           |
| 2025-12-22 | $134555116.40             | $224845327.40           |
| 2025-12-23 | $169518524.10             | $172497620.45           |
| 2025-12-24 | $112089272.90             | $110793950.74           |
| 2025-12-26 | $193930161.28             | $112402700.51           |
| 2025-12-29 | $177022181.29             | $604989317.11           |
| 2025-12-30 | $175043020.83             | $138147746.57           |
| 2025-12-31 | $237553812.84             | $93081051.77            |

**Total Gross Subscriptions (Month):** $4294700681.61

**Total Gross Redemptions (Month):** $4073309923.28

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2025-12-01 | 3.8600%           |
| 2025-12-02 | 3.8500%           |
| 2025-12-03 | 3.8400%           |
| 2025-12-04 | 3.8300%           |
| 2025-12-05 | 3.8000%           |
| 2025-12-08 | 3.7900%           |
| 2025-12-09 | 3.7800%           |
| 2025-12-10 | 3.7800%           |
| 2025-12-11 | 3.7600%           |
| 2025-12-12 | 3.7100%           |
| 2025-12-15 | 3.7000%           |
| 2025-12-16 | 3.6900%           |
| 2025-12-17 | 3.6700%           |
| 2025-12-18 | 3.6700%           |
| 2025-12-19 | 3.6600%           |
| 2025-12-22 | 3.6500%           |
| 2025-12-23 | 3.6500%           |
| 2025-12-24 | 3.6400%           |
| 2025-12-26 | 3.6500%           |
| 2025-12-29 | 3.6600%           |
| 2025-12-30 | 3.6600%           |
| 2025-12-31 | 3.6700%           |

**Beneficial/Record Owner Categories**
| Category                  | Other Category   | Record Owner %   | Beneficial Owner %   |
|:---|:---|:---|:---|
| Non-financial corporation |  | 6.4200%          | 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):** $18824683706.70
- **C.18.a - Value (excl. sponsor support):** $18824683706.70
- **C.19 - Percentage of Net Assets:** 100.0000%
- **C.17 - Yield as of Reporting Date:** 0.0000%
- **C.11 - Maturity Date (WAM):** 2026-01-02
- **C.12 - Maturity Date (WAL):** 2026-01-02
- **C.13 - Final Legal Maturity Date:** 2026-01-02
- **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:** 2026-01-08

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

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

**Title of Signing Officer:** Vice President