# EDGAR Filing Document

**Accession Number:** 0001060517
**File Stem:** 0001410368-26-042927
**Filing Date:** 2026-5
**Character Count:** 18024
**Document Hash:** fdc84e1d51a5e50b19eaa14319f80b3a
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001410368-26-042927.hdr.sgml**: 20260507

**ACCESSION NUMBER**: 0001410368-26-042927

**CONFORMED SUBMISSION TYPE**: N-MFP3

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20260430

**FILED AS OF DATE**: 20260507

**DATE AS OF CHANGE**: 20260507

**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:** 26952708

**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 Institutional Fund (Series ID: S000084282)

| Class ID   | Class Name           | Ticker Symbol   |
|:---|:---|:---|
| C000248579 | Institutional Shares | SIOXX           |
| C000271489 | Token-Enabled Shares | TOKXX           |

# 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):** 2026-04-30

**Registrant Full Name:** UBS Series Funds

**CIK Number of Registrant:** 0001060517

**LEI of Registrant:** 54930058UKPXVB81RJ71

**Name of Series:** UBS Select 100% US Treasury Institutional Fund

**LEI of Series:** 529900KWG787B4G5P791

**EDGAR Series Identifier:** S000084282

**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:** $7678001226.37

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

- **Cash:** $0.00

- **Total Other Assets:** $64913.31

- **Total Liabilities:** $23466549.37

- **Net Assets of Series:** $7654599590.31

- **Number of Shares Outstanding (Series):** 7654402420.4200

- **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 (%)   |
|:---|:---|:---|:---|:---|
| 2026-04-01 | $17883589176.78           | $17883589176.78            | 99.9200%                  | 99.9200%                   |
| 2026-04-02 | $17917479452.71           | $17917479452.71            | 99.9100%                  | 99.9100%                   |
| 2026-04-03 | $0.00                     | $0.00                      | 0.0000%                   | 0.0000%                    |
| 2026-04-06 | $17966031796.31           | $17966031796.31            | 99.9100%                  | 99.9100%                   |
| 2026-04-07 | $17679126391.48           | $17679126391.48            | 99.9100%                  | 99.9100%                   |
| 2026-04-08 | $17697593498.48           | $17697593498.48            | 99.9100%                  | 99.9100%                   |
| 2026-04-09 | $17815143470.01           | $17815143470.01            | 99.9100%                  | 99.9100%                   |
| 2026-04-10 | $17825966178.92           | $17825966178.92            | 99.9100%                  | 99.9100%                   |
| 2026-04-13 | $17685733318.95           | $17685733318.95            | 99.9000%                  | 99.9000%                   |
| 2026-04-14 | $17317754069.39           | $17317754069.39            | 99.9000%                  | 99.9000%                   |
| 2026-04-15 | $17485133616.02           | $17485133616.02            | 99.9100%                  | 99.9100%                   |
| 2026-04-16 | $17410644184.89           | $17410644184.89            | 99.9000%                  | 99.9000%                   |
| 2026-04-17 | $17423698668.60           | $17423698668.60            | 99.9000%                  | 99.9000%                   |
| 2026-04-20 | $17707911949.95           | $17707911949.95            | 99.9000%                  | 99.9000%                   |
| 2026-04-21 | $17385021543.72           | $17385021543.72            | 99.9000%                  | 99.9000%                   |
| 2026-04-22 | $17606474913.96           | $17606474913.96            | 99.9000%                  | 99.9000%                   |
| 2026-04-23 | $17397978068.34           | $17397978068.34            | 99.9000%                  | 99.9000%                   |
| 2026-04-24 | $17489170870.42           | $17489170870.42            | 99.8900%                  | 99.8900%                   |
| 2026-04-27 | $17978017005.53           | $17978017005.53            | 99.9000%                  | 99.9000%                   |
| 2026-04-28 | $17552354181.78           | $17552354181.78            | 99.8900%                  | 99.8900%                   |
| 2026-04-29 | $18522301091.34           | $18522301091.34            | 99.9000%                  | 99.9000%                   |
| 2026-04-30 | $17431760123.21           | $17431760123.21            | 99.9900%                  | 99.9900%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2026-04-01 | 3.7000%             |
| 2026-04-02 | 3.6900%             |
| 2026-04-03 | 0.0000%             |
| 2026-04-06 | 3.6900%             |
| 2026-04-07 | 3.6900%             |
| 2026-04-08 | 3.6900%             |
| 2026-04-09 | 3.6900%             |
| 2026-04-10 | 3.6900%             |
| 2026-04-13 | 3.6900%             |
| 2026-04-14 | 3.6900%             |
| 2026-04-15 | 3.6900%             |
| 2026-04-16 | 3.6900%             |
| 2026-04-17 | 3.6900%             |
| 2026-04-20 | 3.6900%             |
| 2026-04-21 | 3.6900%             |
| 2026-04-22 | 3.6900%             |
| 2026-04-23 | 3.6900%             |
| 2026-04-24 | 3.6900%             |
| 2026-04-27 | 3.6900%             |
| 2026-04-28 | 3.6900%             |
| 2026-04-29 | 3.6900%             |
| 2026-04-30 | 3.6900%             |

### Daily Net Asset Value per Share (Series)
| Date       | Net Asset Value per Share   |
|:---|:---|
| 2026-04-01 | 1.0000                      |
|  |  |
| 2026-04-02 | 1.0000                      |
|  |  |
| 2026-04-03 | 0.0000                      |
|  |  |
| 2026-04-06 | 1.0000                      |
|  |  |
| 2026-04-07 | 1.0000                      |
|  |  |
| 2026-04-08 | 1.0000                      |
|  |  |
| 2026-04-09 | 1.0000                      |
|  |  |
| 2026-04-10 | 1.0000                      |
|  |  |
| 2026-04-13 | 1.0000                      |
|  |  |
| 2026-04-14 | 1.0000                      |
|  |  |
| 2026-04-15 | 1.0000                      |
|  |  |
| 2026-04-16 | 1.0000                      |
|  |  |
| 2026-04-17 | 1.0000                      |
|  |  |
| 2026-04-20 | 1.0000                      |
|  |  |
| 2026-04-21 | 1.0000                      |
|  |  |
| 2026-04-22 | 1.0000                      |
|  |  |
| 2026-04-23 | 1.0000                      |
|  |  |
| 2026-04-24 | 1.0000                      |
|  |  |
| 2026-04-27 | 1.0000                      |
|  |  |
| 2026-04-28 | 1.0000                      |
|  |  |
| 2026-04-29 | 1.0000                      |
|  |  |
| 2026-04-30 | 1.0000                      |
|  |  |

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

### Class: Institutional

- **Minimum Initial Investment:** $1.00

- **Net Assets of Class:** $7654499590.31

- **Number of Shares Outstanding:** 7654302420.4200

- **Expense Reimbursement/Waiver:** 145137.00

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2026-04-01 | 1.0000          |
|  |  |
| 2026-04-02 | 1.0000          |
|  |  |
| 2026-04-03 | 0.0000          |
|  |  |
| 2026-04-06 | 1.0000          |
|  |  |
| 2026-04-07 | 1.0000          |
|  |  |
| 2026-04-08 | 1.0000          |
|  |  |
| 2026-04-09 | 1.0000          |
|  |  |
| 2026-04-10 | 1.0000          |
|  |  |
| 2026-04-13 | 1.0000          |
|  |  |
| 2026-04-14 | 1.0000          |
|  |  |
| 2026-04-15 | 1.0000          |
|  |  |
| 2026-04-16 | 1.0000          |
|  |  |
| 2026-04-17 | 1.0000          |
|  |  |
| 2026-04-20 | 1.0000          |
|  |  |
| 2026-04-21 | 1.0000          |
|  |  |
| 2026-04-22 | 1.0000          |
|  |  |
| 2026-04-23 | 1.0000          |
|  |  |
| 2026-04-24 | 1.0000          |
|  |  |
| 2026-04-27 | 1.0000          |
|  |  |
| 2026-04-28 | 1.0000          |
|  |  |
| 2026-04-29 | 1.0000          |
|  |  |
| 2026-04-30 | 1.0000          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2026-04-01 | $107122928.85             | $84122791.86            |
| 2026-04-02 | $77854503.77              | $69436486.15            |
| 2026-04-03 | $0.00                     | $0.00                   |
| 2026-04-06 | $80360851.16              | $136945568.55           |
| 2026-04-07 | $61060350.90              | $60961604.14            |
| 2026-04-08 | $107864247.84             | $54189210.18            |
| 2026-04-09 | $112191882.67             | $56621476.93            |
| 2026-04-10 | $54053612.80              | $99947824.39            |
| 2026-04-13 | $31108085.94              | $174014564.94           |
| 2026-04-14 | $37956889.96              | $216343322.17           |
| 2026-04-15 | $47042706.78              | $105654516.88           |
| 2026-04-16 | $46641719.06              | $89708731.42            |
| 2026-04-17 | $51427172.23              | $83818442.21            |
| 2026-04-20 | $29770152.44              | $52312369.23            |
| 2026-04-21 | $49154451.79              | $35600853.38            |
| 2026-04-22 | $89261183.07              | $41401290.55            |
| 2026-04-23 | $37101421.31              | $49403804.78            |
| 2026-04-24 | $117018449.37             | $39240468.03            |
| 2026-04-27 | $46928670.75              | $75406114.25            |
| 2026-04-28 | $29374587.46              | $40940494.39            |
| 2026-04-29 | $37426527.98              | $41272510.23            |
| 2026-04-30 | $66276896.14              | $53200772.07            |

**Total Gross Subscriptions (Month):** $1316997292.27

**Total Gross Redemptions (Month):** $1660543216.73

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2026-04-01 | 3.5200%           |
| 2026-04-02 | 3.5100%           |
| 2026-04-03 | 0.0000%           |
| 2026-04-06 | 3.5100%           |
| 2026-04-07 | 3.5100%           |
| 2026-04-08 | 3.5100%           |
| 2026-04-09 | 3.5100%           |
| 2026-04-10 | 3.5100%           |
| 2026-04-13 | 3.5100%           |
| 2026-04-14 | 3.5100%           |
| 2026-04-15 | 3.5100%           |
| 2026-04-16 | 3.5100%           |
| 2026-04-17 | 3.5100%           |
| 2026-04-20 | 3.5100%           |
| 2026-04-21 | 3.5100%           |
| 2026-04-22 | 3.5100%           |
| 2026-04-23 | 3.5100%           |
| 2026-04-24 | 3.5100%           |
| 2026-04-27 | 3.5100%           |
| 2026-04-28 | 3.5100%           |
| 2026-04-29 | 3.5100%           |
| 2026-04-30 | 3.5100%           |

### Class: Token-Enabled Shares

- **Minimum Initial Investment:** $0.00

- **Net Assets of Class:** $100000.00

- **Number of Shares Outstanding:** 100000.0000

- **Expense Reimbursement/Waiver:** 1.00

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2026-04-01 | 1.0000          |
|  |  |
| 2026-04-02 | 1.0000          |
|  |  |
| 2026-04-03 | 0.0000          |
|  |  |
| 2026-04-06 | 1.0000          |
|  |  |
| 2026-04-07 | 1.0000          |
|  |  |
| 2026-04-08 | 1.0000          |
|  |  |
| 2026-04-09 | 1.0000          |
|  |  |
| 2026-04-10 | 1.0000          |
|  |  |
| 2026-04-13 | 1.0000          |
|  |  |
| 2026-04-14 | 1.0000          |
|  |  |
| 2026-04-15 | 1.0000          |
|  |  |
| 2026-04-16 | 1.0000          |
|  |  |
| 2026-04-17 | 1.0000          |
|  |  |
| 2026-04-20 | 1.0000          |
|  |  |
| 2026-04-21 | 1.0000          |
|  |  |
| 2026-04-22 | 1.0000          |
|  |  |
| 2026-04-23 | 1.0000          |
|  |  |
| 2026-04-24 | 1.0000          |
|  |  |
| 2026-04-27 | 1.0000          |
|  |  |
| 2026-04-28 | 1.0000          |
|  |  |
| 2026-04-29 | 1.0000          |
|  |  |
| 2026-04-30 | 1.0000          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2026-04-01 | $0.00                     | $0.00                   |
| 2026-04-02 | $0.00                     | $0.00                   |
| 2026-04-03 | $0.00                     | $0.00                   |
| 2026-04-06 | $0.00                     | $0.00                   |
| 2026-04-07 | $0.00                     | $0.00                   |
| 2026-04-08 | $0.00                     | $0.00                   |
| 2026-04-09 | $0.00                     | $0.00                   |
| 2026-04-10 | $0.00                     | $0.00                   |
| 2026-04-13 | $0.00                     | $0.00                   |
| 2026-04-14 | $0.00                     | $0.00                   |
| 2026-04-15 | $0.00                     | $0.00                   |
| 2026-04-16 | $0.00                     | $0.00                   |
| 2026-04-17 | $0.00                     | $0.00                   |
| 2026-04-20 | $0.00                     | $0.00                   |
| 2026-04-21 | $0.00                     | $0.00                   |
| 2026-04-22 | $0.00                     | $0.00                   |
| 2026-04-23 | $0.00                     | $0.00                   |
| 2026-04-24 | $0.00                     | $0.00                   |
| 2026-04-27 | $0.00                     | $0.00                   |
| 2026-04-28 | $0.00                     | $0.00                   |
| 2026-04-29 | $0.00                     | $0.00                   |
| 2026-04-30 | $0.00                     | $0.00                   |

**Total Gross Subscriptions (Month):** $0.00

**Total Gross Redemptions (Month):** $0.00

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2026-04-01 | 3.5200%           |
| 2026-04-02 | 3.5100%           |
| 2026-04-03 | 0.0000%           |
| 2026-04-06 | 3.5100%           |
| 2026-04-07 | 3.5100%           |
| 2026-04-08 | 3.5100%           |
| 2026-04-09 | 3.5100%           |
| 2026-04-10 | 3.5100%           |
| 2026-04-13 | 3.5100%           |
| 2026-04-14 | 3.5100%           |
| 2026-04-15 | 3.5100%           |
| 2026-04-16 | 3.5100%           |
| 2026-04-17 | 3.5100%           |
| 2026-04-20 | 3.5100%           |
| 2026-04-21 | 3.5100%           |
| 2026-04-22 | 3.5100%           |
| 2026-04-23 | 3.5100%           |
| 2026-04-24 | 3.5100%           |
| 2026-04-27 | 3.5100%           |
| 2026-04-28 | 3.5100%           |
| 2026-04-29 | 3.5100%           |
| 2026-04-30 | 3.5100%           |

**Beneficial/Record Owner Categories**
| Category                  | Other Category   | Record Owner %   | Beneficial Owner %   |
|:---|:---|:---|:---|
| Non-financial corporation |  | 100.0000%        | 0.0000%              |

## 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):** $7678001226.37
- **C.18.a - Value (excl. sponsor support):** $7678001226.37
- **C.19 - Percentage of Net Assets:** 100.0000%
- **C.17 - Yield as of Reporting Date:** 0.0000%
- **C.11 - Maturity Date (WAM):** 2026-05-01
- **C.12 - Maturity Date (WAL):** 2026-05-01
- **C.13 - Final Legal Maturity Date:** 2026-05-01
- **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:** 2026-05-07

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

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

**Title of Signing Officer:** Vice President