# EDGAR Filing Document

**Accession Number:** 0001060517
**File Stem:** 0001410368-26-000468
**Filing Date:** 2026-1
**Character Count:** 13921
**Document Hash:** 3fde043be41cbe27baaa6012e0b51048
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001410368-26-000468.hdr.sgml**: 20260108

**ACCESSION NUMBER**: 0001410368-26-000468

**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:** 26520426

**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 Prime Preferred Fund (Series ID: S000052307)

| Class ID   | Class Name               | Ticker Symbol   |
|:---|:---|:---|
| C000164453 | UBS Prime Preferred Fund | UPPXX           |

# 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 Prime Preferred Fund

**LEI of Series:** 5493001YQBD9A4ZH6D79

**EDGAR Series Identifier:** S000052307

**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:** Prime

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

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

- **WAM:** 1 days

- **WAL:** 1 days

- **Total Value of Portfolio Securities:** $10163820328.01

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

- **Cash:** $0.00

- **Total Other Assets:** $0.00

- **Total Liabilities:** $33721483.55

- **Net Assets of Series:** $10130098844.46

- **Number of Shares Outstanding (Series):** 10129431124.5910

- **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 | $10810896161.04           | $12945233660.24            | 42.7600%                  | 51.2000%                   |
| 2025-12-02 | $12204074405.06           | $13012689196.56            | 48.1400%                  | 51.3300%                   |
| 2025-12-03 | $11096333679.89           | $13009381020.89            | 43.6300%                  | 51.1500%                   |
| 2025-12-04 | $11005201015.63           | $12878384731.13            | 43.4900%                  | 50.8900%                   |
| 2025-12-05 | $11599630715.73           | $13053154659.73            | 45.7400%                  | 51.4700%                   |
| 2025-12-08 | $11017293324.79           | $13015699112.29            | 43.2900%                  | 51.1500%                   |
| 2025-12-09 | $11969280493.26           | $12862929618.26            | 47.3200%                  | 50.8500%                   |
| 2025-12-10 | $11406580959.02           | $12814984116.52            | 45.1800%                  | 50.7600%                   |
| 2025-12-11 | $11058681869.77           | $12886811832.17            | 43.7000%                  | 50.9300%                   |
| 2025-12-12 | $11566780630.67           | $12850235418.57            | 45.7700%                  | 50.8500%                   |
| 2025-12-15 | $11240530705.16           | $13019017457.26            | 44.6200%                  | 51.6800%                   |
| 2025-12-16 | $11817721829.09           | $13036386385.09            | 46.8800%                  | 51.7100%                   |
| 2025-12-17 | $12130825898.57           | $13149392016.07            | 47.9100%                  | 51.9300%                   |
| 2025-12-18 | $11954519665.29           | $12973158726.79            | 47.5100%                  | 51.5500%                   |
| 2025-12-19 | $12482381449.47           | $13006204823.97            | 49.5700%                  | 51.6500%                   |
| 2025-12-22 | $12221893630.61           | $13005636398.61            | 48.5400%                  | 51.6500%                   |
| 2025-12-23 | $12616088752.11           | $13054928826.11            | 50.0100%                  | 51.7500%                   |
| 2025-12-24 | $12347823360.77           | $13361480577.27            | 48.8300%                  | 52.8400%                   |
| 2025-12-26 | $12605366992.12           | $13409165219.62            | 49.8400%                  | 53.0200%                   |
| 2025-12-29 | $12418941443.96           | $13557682734.96            | 49.0100%                  | 53.5100%                   |
| 2025-12-30 | $12768963492.64           | $13724681316.74            | 50.2400%                  | 54.0000%                   |
| 2025-12-31 | $13087414305.45           | $13968134124.25            | 51.2500%                  | 54.7000%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2025-12-01 | 4.1500%             |
| 2025-12-02 | 4.1500%             |
| 2025-12-03 | 4.1400%             |
| 2025-12-04 | 4.1300%             |
| 2025-12-05 | 4.0900%             |
| 2025-12-08 | 4.0800%             |
| 2025-12-09 | 4.0700%             |
| 2025-12-10 | 4.0700%             |
| 2025-12-11 | 4.0500%             |
| 2025-12-12 | 3.9900%             |
| 2025-12-15 | 3.9600%             |
| 2025-12-16 | 3.9400%             |
| 2025-12-17 | 3.9200%             |
| 2025-12-18 | 3.9100%             |
| 2025-12-19 | 3.9000%             |
| 2025-12-22 | 3.8900%             |
| 2025-12-23 | 3.8900%             |
| 2025-12-24 | 3.8800%             |
| 2025-12-26 | 3.9000%             |
| 2025-12-29 | 3.9100%             |
| 2025-12-30 | 3.9100%             |
| 2025-12-31 | 3.9300%             |

### Daily Net Asset Value per Share (Series)
| Date       | Net Asset Value per Share   |
|:---|:---|
| 2025-12-01 | 1.0001                      |
|  |  |
| 2025-12-02 | 1.0001                      |
|  |  |
| 2025-12-03 | 1.0001                      |
|  |  |
| 2025-12-04 | 1.0001                      |
|  |  |
| 2025-12-05 | 1.0000                      |
|  |  |
| 2025-12-08 | 1.0001                      |
|  |  |
| 2025-12-09 | 1.0001                      |
|  |  |
| 2025-12-10 | 1.0001                      |
|  |  |
| 2025-12-11 | 1.0002                      |
|  |  |
| 2025-12-12 | 1.0001                      |
|  |  |
| 2025-12-15 | 1.0002                      |
|  |  |
| 2025-12-16 | 1.0002                      |
|  |  |
| 2025-12-17 | 1.0002                      |
|  |  |
| 2025-12-18 | 1.0002                      |
|  |  |
| 2025-12-19 | 1.0001                      |
|  |  |
| 2025-12-22 | 1.0002                      |
|  |  |
| 2025-12-23 | 1.0002                      |
|  |  |
| 2025-12-24 | 1.0001                      |
|  |  |
| 2025-12-26 | 1.0001                      |
|  |  |
| 2025-12-29 | 1.0002                      |
|  |  |
| 2025-12-30 | 1.0002                      |
|  |  |
| 2025-12-31 | 1.0001                      |
|  |  |

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

### Class: Single Class

- **Minimum Initial Investment:** $50000000.00

- **Net Assets of Class:** $10130098844.46

- **Number of Shares Outstanding:** 10129431124.5910

- **Expense Reimbursement/Waiver:** 352808.00

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2025-12-01 | 1.0001          |
|  |  |
| 2025-12-02 | 1.0001          |
|  |  |
| 2025-12-03 | 1.0001          |
|  |  |
| 2025-12-04 | 1.0001          |
|  |  |
| 2025-12-05 | 1.0000          |
|  |  |
| 2025-12-08 | 1.0001          |
|  |  |
| 2025-12-09 | 1.0001          |
|  |  |
| 2025-12-10 | 1.0001          |
|  |  |
| 2025-12-11 | 1.0002          |
|  |  |
| 2025-12-12 | 1.0001          |
|  |  |
| 2025-12-15 | 1.0002          |
|  |  |
| 2025-12-16 | 1.0002          |
|  |  |
| 2025-12-17 | 1.0002          |
|  |  |
| 2025-12-18 | 1.0002          |
|  |  |
| 2025-12-19 | 1.0001          |
|  |  |
| 2025-12-22 | 1.0002          |
|  |  |
| 2025-12-23 | 1.0002          |
|  |  |
| 2025-12-24 | 1.0001          |
|  |  |
| 2025-12-26 | 1.0001          |
|  |  |
| 2025-12-29 | 1.0002          |
|  |  |
| 2025-12-30 | 1.0002          |
|  |  |
| 2025-12-31 | 1.0001          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2025-12-01 | $82470294.10              | $92119846.59            |
| 2025-12-02 | $103359165.37             | $64869206.56            |
| 2025-12-03 | $53820008.57              | $51772217.45            |
| 2025-12-04 | $31622051.03              | $52410987.32            |
| 2025-12-05 | $64722395.95              | $60298788.18            |
| 2025-12-08 | $77343906.55              | $87744044.21            |
| 2025-12-09 | $33733738.80              | $60267390.15            |
| 2025-12-10 | $43055158.13              | $66832628.07            |
| 2025-12-11 | $56910287.71              | $63001680.80            |
| 2025-12-12 | $72643906.45              | $52054500.00            |
| 2025-12-15 | $39858851.17              | $89324726.36            |
| 2025-12-16 | $90252406.45              | $64270383.42            |
| 2025-12-17 | $51164341.25              | $64993945.32            |
| 2025-12-18 | $63536770.23              | $67278749.84            |
| 2025-12-19 | $72877549.56              | $91279505.98            |
| 2025-12-22 | $71708542.26              | $85012069.06            |
| 2025-12-23 | $79967900.69              | $55433035.58            |
| 2025-12-24 | $64060959.44              | $47894409.60            |
| 2025-12-26 | $44031102.31              | $41867436.73            |
| 2025-12-29 | $88793360.94              | $82280969.39            |
| 2025-12-30 | $60164381.28              | $44458092.39            |
| 2025-12-31 | $115653013.21             | $43772693.05            |

**Total Gross Subscriptions (Month):** $1461750091.45

**Total Gross Redemptions (Month):** $1429237306.05

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2025-12-01 | 4.0100%           |
| 2025-12-02 | 4.0100%           |
| 2025-12-03 | 4.0000%           |
| 2025-12-04 | 3.9900%           |
| 2025-12-05 | 3.9500%           |
| 2025-12-08 | 3.9400%           |
| 2025-12-09 | 3.9300%           |
| 2025-12-10 | 3.9300%           |
| 2025-12-11 | 3.9100%           |
| 2025-12-12 | 3.8500%           |
| 2025-12-15 | 3.8200%           |
| 2025-12-16 | 3.8000%           |
| 2025-12-17 | 3.7800%           |
| 2025-12-18 | 3.7700%           |
| 2025-12-19 | 3.7600%           |
| 2025-12-22 | 3.7500%           |
| 2025-12-23 | 3.7500%           |
| 2025-12-24 | 3.7400%           |
| 2025-12-26 | 3.7600%           |
| 2025-12-29 | 3.7700%           |
| 2025-12-30 | 3.7700%           |
| 2025-12-31 | 3.7900%           |

## Part C: Schedule of Portfolio Securities

### Security 1: Prime CNAV Master Fund

- **C.1 - Title:** Prime CNAV Master Fund
- **C.6 - Investment Category:** Investment Company
- **Identifiers:** C.3 - CUSIP: 927XQC905, C.3 - LEI: 549300K8VKMIOPMVLW91, C.5 - Other ID: 927XQC905
- **C.18 - Value (incl. sponsor support):** $10163820328.01
- **C.18.a - Value (excl. sponsor support):** $10163820328.01
- **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