# EDGAR Filing Document

**Accession Number:** 0001060517
**File Stem:** 0001410368-26-034973
**Filing Date:** 2026-4
**Character Count:** 17775
**Document Hash:** 8bc510f48d5c0f5b74ea6eb9ad75d774
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001410368-26-034973.hdr.sgml**: 20260407

**ACCESSION NUMBER**: 0001410368-26-034973

**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:** 26843753

**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):** 2026-03-31

**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:** $9425355273.10

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

- **Cash:** $0.00

- **Total Other Assets:** $42054.63

- **Total Liabilities:** $28664600.89

- **Net Assets of Series:** $9396732726.84

- **Number of Shares Outstanding (Series):** 9396532797.0800

- **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 | $17889271877.46           | $17889271877.46            | 99.9300%                  | 99.9300%                   |
| 2026-03-03 | $17780955792.49           | $17780955792.49            | 99.9300%                  | 99.9300%                   |
| 2026-03-04 | $17995676595.42           | $17995676595.42            | 99.9300%                  | 99.9300%                   |
| 2026-03-05 | $17848740399.34           | $17848740399.34            | 99.9300%                  | 99.9300%                   |
| 2026-03-06 | $17885550745.70           | $17885550745.70            | 99.9300%                  | 99.9300%                   |
| 2026-03-09 | $18113143739.31           | $18113143739.31            | 99.9300%                  | 99.9300%                   |
| 2026-03-10 | $17972151500.91           | $17972151500.91            | 99.9200%                  | 99.9200%                   |
| 2026-03-11 | $18230881957.70           | $18230881957.70            | 99.9200%                  | 99.9200%                   |
| 2026-03-12 | $18123918549.51           | $18123918549.51            | 99.9200%                  | 99.9200%                   |
| 2026-03-13 | $18356458571.25           | $18356458571.25            | 99.9200%                  | 99.9200%                   |
| 2026-03-16 | $18422221264.62           | $18422221264.62            | 99.9300%                  | 99.9300%                   |
| 2026-03-17 | $18048397611.78           | $18048397611.78            | 99.9200%                  | 99.9200%                   |
| 2026-03-18 | $18314987401.10           | $18314987401.10            | 99.9200%                  | 99.9200%                   |
| 2026-03-19 | $18231905050.66           | $18231905050.66            | 99.9200%                  | 99.9200%                   |
| 2026-03-20 | $18021921666.56           | $18021921666.56            | 99.9200%                  | 99.9200%                   |
| 2026-03-23 | $18209294953.48           | $18209294953.48            | 99.9200%                  | 99.9200%                   |
| 2026-03-24 | $17873459827.61           | $17873459827.61            | 99.9100%                  | 99.9100%                   |
| 2026-03-25 | $17979897450.59           | $17979897450.59            | 99.9100%                  | 99.9100%                   |
| 2026-03-26 | $18020509092.41           | $18020509092.41            | 99.9100%                  | 99.9100%                   |
| 2026-03-27 | $17929891424.71           | $17929891424.71            | 99.9100%                  | 99.9100%                   |
| 2026-03-30 | $18070124997.50           | $18070124997.50            | 99.9100%                  | 99.9100%                   |
| 2026-03-31 | $17783469598.92           | $17783469598.92            | 99.9200%                  | 99.9200%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2026-03-02 | 3.7000%             |
| 2026-03-03 | 3.7000%             |
| 2026-03-04 | 3.6900%             |
| 2026-03-05 | 3.6900%             |
| 2026-03-06 | 3.6900%             |
| 2026-03-09 | 3.6900%             |
| 2026-03-10 | 3.6900%             |
| 2026-03-11 | 3.6900%             |
| 2026-03-12 | 3.6900%             |
| 2026-03-13 | 3.6900%             |
| 2026-03-16 | 3.6900%             |
| 2026-03-17 | 3.6900%             |
| 2026-03-18 | 3.6900%             |
| 2026-03-19 | 3.6900%             |
| 2026-03-20 | 3.6900%             |
| 2026-03-23 | 3.6900%             |
| 2026-03-24 | 3.6900%             |
| 2026-03-25 | 3.6900%             |
| 2026-03-26 | 3.7000%             |
| 2026-03-27 | 3.7000%             |
| 2026-03-30 | 3.7000%             |
| 2026-03-31 | 3.7000%             |

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

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

### Class: Class P

- **Minimum Initial Investment:** $1.00

- **Net Assets of Class:** $567169473.79

- **Number of Shares Outstanding:** 567156497.8200

- **Expense Reimbursement/Waiver:** 20681.00

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

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2026-03-02 | $3022846.31               | $31256628.84            |
| 2026-03-03 | $5828382.48               | $6363261.29             |
| 2026-03-04 | $7025781.57               | $6804593.47             |
| 2026-03-05 | $10043564.97              | $2510595.08             |
| 2026-03-06 | $6905894.17               | $1253117.84             |
| 2026-03-09 | $1468798.53               | $7118556.46             |
| 2026-03-10 | $2562321.88               | $4764720.80             |
| 2026-03-11 | $28221964.03              | $4058278.64             |
| 2026-03-12 | $5010140.00               | $10228559.60            |
| 2026-03-13 | $9561820.27               | $6459074.47             |
| 2026-03-16 | $6927041.56               | $3591672.39             |
| 2026-03-17 | $3612848.83               | $4231351.18             |
| 2026-03-18 | $13971054.85              | $3339482.52             |
| 2026-03-19 | $19252327.81              | $3169402.65             |
| 2026-03-20 | $5585240.84               | $1537008.34             |
| 2026-03-23 | $7668973.55               | $8085584.29             |
| 2026-03-24 | $14895506.64              | $9061609.48             |
| 2026-03-25 | $10721774.24              | $6656903.94             |
| 2026-03-26 | $4172526.26               | $3021645.00             |
| 2026-03-27 | $1344459.08               | $5514834.15             |
| 2026-03-30 | $2375658.82               | $4831091.12             |
| 2026-03-31 | $4409367.20               | $2326512.10             |

**Total Gross Subscriptions (Month):** $174588293.89

**Total Gross Redemptions (Month):** $136184483.65

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2026-03-02 | 3.5600%           |
| 2026-03-03 | 3.5600%           |
| 2026-03-04 | 3.5500%           |
| 2026-03-05 | 3.5500%           |
| 2026-03-06 | 3.5500%           |
| 2026-03-09 | 3.5500%           |
| 2026-03-10 | 3.5500%           |
| 2026-03-11 | 3.5500%           |
| 2026-03-12 | 3.5500%           |
| 2026-03-13 | 3.5500%           |
| 2026-03-16 | 3.5500%           |
| 2026-03-17 | 3.5500%           |
| 2026-03-18 | 3.5500%           |
| 2026-03-19 | 3.5500%           |
| 2026-03-20 | 3.5500%           |
| 2026-03-23 | 3.5500%           |
| 2026-03-24 | 3.5500%           |
| 2026-03-25 | 3.5500%           |
| 2026-03-26 | 3.5600%           |
| 2026-03-27 | 3.5600%           |
| 2026-03-30 | 3.5600%           |
| 2026-03-31 | 3.5600%           |

### Class: Class T

- **Minimum Initial Investment:** $5000000.00

- **Net Assets of Class:** $8829563253.05

- **Number of Shares Outstanding:** 8829376299.2600

- **Expense Reimbursement/Waiver:** 333168.00

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

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2026-03-02 | $26119830.38              | $20597580.76            |
| 2026-03-03 | $14809401.12              | $3291328.98             |
| 2026-03-04 | $3950027.70               | $3702569.82             |
| 2026-03-05 | $33856610.27              | $11810715.09            |
| 2026-03-06 | $22444039.09              | $32066128.80            |
| 2026-03-09 | $112102493.85             | $35041051.48            |
| 2026-03-10 | $20064891.13              | $5433326.24             |
| 2026-03-11 | $10968009.57              | $19223990.11            |
| 2026-03-12 | $116987325.45             | $27328812.16            |
| 2026-03-13 | $231219126.25             | $5793249.35             |
| 2026-03-16 | $5788099.46               | $26692219.85            |
| 2026-03-17 | $6800961.43               | $170822737.95           |
| 2026-03-18 | $149834876.74             | $26183596.59            |
| 2026-03-19 | $79586612.19              | $106994169.27           |
| 2026-03-20 | $38414029.54              | $252987246.95           |
| 2026-03-23 | $34134659.83              | $65321385.23            |
| 2026-03-24 | $66967924.03              | $53481556.62            |
| 2026-03-25 | $4905925.87               | $12123716.21            |
| 2026-03-26 | $1007498.54               | $11749218.01            |
| 2026-03-27 | $24958402.81              | $16499329.75            |
| 2026-03-30 | $19842477.93              | $24954354.25            |
| 2026-03-31 | $71013682.43              | $39481263.95            |

**Total Gross Subscriptions (Month):** $1095776905.61

**Total Gross Redemptions (Month):** $971579547.42

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2026-03-02 | 3.5600%           |
| 2026-03-03 | 3.5600%           |
| 2026-03-04 | 3.5500%           |
| 2026-03-05 | 3.5500%           |
| 2026-03-06 | 3.5500%           |
| 2026-03-09 | 3.5500%           |
| 2026-03-10 | 3.5500%           |
| 2026-03-11 | 3.5500%           |
| 2026-03-12 | 3.5500%           |
| 2026-03-13 | 3.5500%           |
| 2026-03-16 | 3.5500%           |
| 2026-03-17 | 3.5500%           |
| 2026-03-18 | 3.5500%           |
| 2026-03-19 | 3.5500%           |
| 2026-03-20 | 3.5500%           |
| 2026-03-23 | 3.5500%           |
| 2026-03-24 | 3.5500%           |
| 2026-03-25 | 3.5500%           |
| 2026-03-26 | 3.5600%           |
| 2026-03-27 | 3.5600%           |
| 2026-03-30 | 3.5600%           |
| 2026-03-31 | 3.5600%           |

## 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):** $9425355273.10
- **C.18.a - Value (excl. sponsor support):** $9425355273.10
- **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