# EDGAR Filing Document

**Accession Number:** 0001060517
**File Stem:** 0001410368-26-057293
**Filing Date:** 2026-6
**Character Count:** 16757
**Document Hash:** 60974529f71ebc72b38fee7516eed75c
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001410368-26-057293.hdr.sgml**: 20260605

**ACCESSION NUMBER**: 0001410368-26-057293

**CONFORMED SUBMISSION TYPE**: N-MFP3

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20260531

**FILED AS OF DATE**: 20260605

**DATE AS OF CHANGE**: 20260605

**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:** 261068600

**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):** 2026-05-31

**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:** $9316744478.84

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

- **Cash:** $0.00

- **Total Other Assets:** $48497.45

- **Total Liabilities:** $28805373.97

- **Net Assets of Series:** $9287987602.32

- **Number of Shares Outstanding (Series):** 9287783144.7600

- **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 (%)   |
|:---|:---|:---|:---|:---|
| 2026-05-01 | $17590632888.67           | $17590632888.67            | 99.9900%                  | 99.9900%                   |
| 2026-05-04 | $18059786225.56           | $18059786225.56            | 99.9900%                  | 99.9900%                   |
| 2026-05-05 | $17747430029.04           | $17747430029.04            | 99.9900%                  | 99.9900%                   |
| 2026-05-06 | $18414068850.19           | $18414068850.19            | 99.9900%                  | 99.9900%                   |
| 2026-05-07 | $17560079099.33           | $17560079099.33            | 99.9900%                  | 99.9900%                   |
| 2026-05-08 | $17673684129.47           | $17673684129.47            | 99.9800%                  | 99.9800%                   |
| 2026-05-11 | $18015815968.26           | $18015815968.26            | 99.9800%                  | 99.9800%                   |
| 2026-05-12 | $17679166162.93           | $17679166162.93            | 99.9800%                  | 99.9800%                   |
| 2026-05-13 | $17847646712.83           | $17847646712.83            | 99.9800%                  | 99.9800%                   |
| 2026-05-14 | $17709803856.11           | $17709803856.11            | 99.9800%                  | 99.9800%                   |
| 2026-05-15 | $17841277802.81           | $17841277802.81            | 99.9900%                  | 99.9900%                   |
| 2026-05-18 | $18305127028.28           | $18305127028.28            | 99.9900%                  | 99.9900%                   |
| 2026-05-19 | $17957072625.46           | $17957072625.46            | 99.9800%                  | 99.9800%                   |
| 2026-05-20 | $18034645015.73           | $18034645015.73            | 99.9800%                  | 99.9800%                   |
| 2026-05-21 | $17880514252.81           | $17880514252.81            | 99.9800%                  | 99.9800%                   |
| 2026-05-22 | $17855207636.45           | $17855207636.45            | 99.9800%                  | 99.9800%                   |
| 2026-05-26 | $17817261048.00           | $17817261048.00            | 99.9800%                  | 99.9800%                   |
| 2026-05-27 | $18065914231.94           | $18065914231.94            | 99.9800%                  | 99.9800%                   |
| 2026-05-28 | $17883528495.44           | $17883528495.44            | 99.9800%                  | 99.9800%                   |
| 2026-05-29 | $17790264832.60           | $17790264832.60            | 99.9700%                  | 99.9700%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2026-05-01 | 3.6800%             |
| 2026-05-04 | 3.6800%             |
| 2026-05-05 | 3.6800%             |
| 2026-05-06 | 3.6700%             |
| 2026-05-07 | 3.6700%             |
| 2026-05-08 | 3.6700%             |
| 2026-05-11 | 3.6700%             |
| 2026-05-12 | 3.6700%             |
| 2026-05-13 | 3.6700%             |
| 2026-05-14 | 3.6800%             |
| 2026-05-15 | 3.6800%             |
| 2026-05-18 | 3.6800%             |
| 2026-05-19 | 3.6800%             |
| 2026-05-20 | 3.6800%             |
| 2026-05-21 | 3.6800%             |
| 2026-05-22 | 3.6800%             |
| 2026-05-26 | 3.6700%             |
| 2026-05-27 | 3.6700%             |
| 2026-05-28 | 3.6800%             |
| 2026-05-29 | 3.6800%             |

### Daily Net Asset Value per Share (Series)
| Date       | Net Asset Value per Share   |
|:---|:---|
| 2026-05-01 | 1.0000                      |
|  |  |
| 2026-05-04 | 1.0000                      |
|  |  |
| 2026-05-05 | 1.0001                      |
|  |  |
| 2026-05-06 | 1.0001                      |
|  |  |
| 2026-05-07 | 1.0000                      |
|  |  |
| 2026-05-08 | 1.0001                      |
|  |  |
| 2026-05-11 | 1.0000                      |
|  |  |
| 2026-05-12 | 1.0000                      |
|  |  |
| 2026-05-13 | 1.0000                      |
|  |  |
| 2026-05-14 | 1.0000                      |
|  |  |
| 2026-05-15 | 1.0000                      |
|  |  |
| 2026-05-18 | 1.0001                      |
|  |  |
| 2026-05-19 | 1.0001                      |
|  |  |
| 2026-05-20 | 1.0001                      |
|  |  |
| 2026-05-21 | 1.0001                      |
|  |  |
| 2026-05-22 | 1.0000                      |
|  |  |
| 2026-05-26 | 1.0000                      |
|  |  |
| 2026-05-27 | 1.0000                      |
|  |  |
| 2026-05-28 | 1.0000                      |
|  |  |
| 2026-05-29 | 1.0000                      |
|  |  |

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

### Class: Class P

- **Minimum Initial Investment:** $1.00

- **Net Assets of Class:** $560058893.26

- **Number of Shares Outstanding:** 560045636.5300

- **Expense Reimbursement/Waiver:** 26656.00

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2026-05-01 | 1.0000          |
|  |  |
| 2026-05-04 | 1.0000          |
|  |  |
| 2026-05-05 | 1.0001          |
|  |  |
| 2026-05-06 | 1.0001          |
|  |  |
| 2026-05-07 | 1.0001          |
|  |  |
| 2026-05-08 | 1.0001          |
|  |  |
| 2026-05-11 | 1.0000          |
|  |  |
| 2026-05-12 | 1.0000          |
|  |  |
| 2026-05-13 | 1.0000          |
|  |  |
| 2026-05-14 | 1.0000          |
|  |  |
| 2026-05-15 | 1.0000          |
|  |  |
| 2026-05-18 | 1.0001          |
|  |  |
| 2026-05-19 | 1.0001          |
|  |  |
| 2026-05-20 | 1.0001          |
|  |  |
| 2026-05-21 | 1.0001          |
|  |  |
| 2026-05-22 | 1.0000          |
|  |  |
| 2026-05-26 | 1.0000          |
|  |  |
| 2026-05-27 | 1.0000          |
|  |  |
| 2026-05-28 | 1.0000          |
|  |  |
| 2026-05-29 | 1.0000          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2026-05-01 | $6973806.62               | $4709620.02             |
| 2026-05-04 | $14664242.63              | $9872828.87             |
| 2026-05-05 | $13135348.00              | $11920357.12            |
| 2026-05-06 | $3738159.38               | $5244014.60             |
| 2026-05-07 | $5897798.83               | $2716438.83             |
| 2026-05-08 | $3247449.36               | $3723042.62             |
| 2026-05-11 | $4309915.35               | $3424523.61             |
| 2026-05-12 | $5949334.62               | $2546099.73             |
| 2026-05-13 | $9695730.88               | $7436727.28             |
| 2026-05-14 | $2827093.06               | $4299011.61             |
| 2026-05-15 | $12810038.41              | $2659831.17             |
| 2026-05-18 | $4628623.72               | $4553712.47             |
| 2026-05-19 | $2956033.64               | $9624145.25             |
| 2026-05-20 | $2084629.20               | $16274730.10            |
| 2026-05-21 | $4961575.50               | $3865729.88             |
| 2026-05-22 | $5366760.44               | $4470425.62             |
| 2026-05-26 | $4914043.81               | $9436941.77             |
| 2026-05-27 | $2299406.97               | $8266397.89             |
| 2026-05-28 | $3683985.70               | $8995530.84             |
| 2026-05-29 | $5389099.87               | $2751913.23             |

**Total Gross Subscriptions (Month):** $119533075.99

**Total Gross Redemptions (Month):** $126792022.51

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2026-05-01 | 3.5400%           |
| 2026-05-04 | 3.5400%           |
| 2026-05-05 | 3.5400%           |
| 2026-05-06 | 3.5300%           |
| 2026-05-07 | 3.5300%           |
| 2026-05-08 | 3.5300%           |
| 2026-05-11 | 3.5300%           |
| 2026-05-12 | 3.5300%           |
| 2026-05-13 | 3.5300%           |
| 2026-05-14 | 3.5400%           |
| 2026-05-15 | 3.5400%           |
| 2026-05-18 | 3.5400%           |
| 2026-05-19 | 3.5400%           |
| 2026-05-20 | 3.5400%           |
| 2026-05-21 | 3.5400%           |
| 2026-05-22 | 3.5400%           |
| 2026-05-26 | 3.5300%           |
| 2026-05-27 | 3.5300%           |
| 2026-05-28 | 3.5400%           |
| 2026-05-29 | 3.5400%           |

### Class: Class T

- **Minimum Initial Investment:** $5000000.00

- **Net Assets of Class:** $8727928709.06

- **Number of Shares Outstanding:** 8727737508.2300

- **Expense Reimbursement/Waiver:** 402597.00

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2026-05-01 | 1.0000          |
|  |  |
| 2026-05-04 | 1.0000          |
|  |  |
| 2026-05-05 | 1.0001          |
|  |  |
| 2026-05-06 | 1.0001          |
|  |  |
| 2026-05-07 | 1.0000          |
|  |  |
| 2026-05-08 | 1.0001          |
|  |  |
| 2026-05-11 | 1.0000          |
|  |  |
| 2026-05-12 | 1.0000          |
|  |  |
| 2026-05-13 | 1.0000          |
|  |  |
| 2026-05-14 | 1.0000          |
|  |  |
| 2026-05-15 | 1.0000          |
|  |  |
| 2026-05-18 | 1.0001          |
|  |  |
| 2026-05-19 | 1.0001          |
|  |  |
| 2026-05-20 | 1.0001          |
|  |  |
| 2026-05-21 | 1.0001          |
|  |  |
| 2026-05-22 | 1.0000          |
|  |  |
| 2026-05-26 | 1.0000          |
|  |  |
| 2026-05-27 | 1.0000          |
|  |  |
| 2026-05-28 | 1.0000          |
|  |  |
| 2026-05-29 | 1.0000          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2026-05-01 | $111854114.91             | $36364449.35            |
| 2026-05-04 | $114152970.50             | $23329255.46            |
| 2026-05-05 | $19027000.81              | $16098526.35            |
| 2026-05-06 | $38198750.07              | $18809479.47            |
| 2026-05-07 | $93644607.87              | $309627768.48           |
| 2026-05-08 | $94148178.79              | $5577140.28             |
| 2026-05-11 | $13784522.67              | $12455290.31            |
| 2026-05-12 | $17501001.05              | $22921081.27            |
| 2026-05-13 | $30241270.39              | $33818352.51            |
| 2026-05-14 | $67444272.90              | $9933430.58             |
| 2026-05-15 | $12756998.94              | $31864076.59            |
| 2026-05-18 | $43707993.89              | $15074938.53            |
| 2026-05-19 | $11692740.34              | $17353349.42            |
| 2026-05-20 | $10066779.30              | $24153287.23            |
| 2026-05-21 | $33053391.16              | $14668508.88            |
| 2026-05-22 | $8438120.34               | $28707856.81            |
| 2026-05-26 | $53524592.71              | $55564447.25            |
| 2026-05-27 | $90155702.18              | $58314834.05            |
| 2026-05-28 | $61350747.02              | $71481797.35            |
| 2026-05-29 | $2067973.16               | $44650252.05            |

**Total Gross Subscriptions (Month):** $926811729.00

**Total Gross Redemptions (Month):** $850768122.22

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2026-05-01 | 3.5400%           |
| 2026-05-04 | 3.5400%           |
| 2026-05-05 | 3.5400%           |
| 2026-05-06 | 3.5300%           |
| 2026-05-07 | 3.5300%           |
| 2026-05-08 | 3.5300%           |
| 2026-05-11 | 3.5300%           |
| 2026-05-12 | 3.5300%           |
| 2026-05-13 | 3.5300%           |
| 2026-05-14 | 3.5400%           |
| 2026-05-15 | 3.5400%           |
| 2026-05-18 | 3.5400%           |
| 2026-05-19 | 3.5400%           |
| 2026-05-20 | 3.5400%           |
| 2026-05-21 | 3.5400%           |
| 2026-05-22 | 3.5400%           |
| 2026-05-26 | 3.5300%           |
| 2026-05-27 | 3.5300%           |
| 2026-05-28 | 3.5400%           |
| 2026-05-29 | 3.5400%           |

## 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):** $9316744478.84
- **C.18.a - Value (excl. sponsor support):** $9316744478.84
- **C.19 - Percentage of Net Assets:** 100.0000%
- **C.17 - Yield as of Reporting Date:** 0.0000%
- **C.11 - Maturity Date (WAM):** 2026-06-01
- **C.12 - Maturity Date (WAL):** 2026-06-01
- **C.13 - Final Legal Maturity Date:** 2026-06-01
- **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:** 2026-06-05

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

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

**Title of Signing Officer:** Vice President