# EDGAR Filing Document

**Accession Number:** 0001060517
**File Stem:** 0001410368-26-057291
**Filing Date:** 2026-6
**Character Count:** 13142
**Document Hash:** 6d1709af20193de179a6b6ed232c984d
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001410368-26-057291.hdr.sgml**: 20260605

**ACCESSION NUMBER**: 0001410368-26-057291

**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:** 261068595

**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 Reserves Fund (Series ID: S000052306)

| Class ID   | Class Name              | Ticker Symbol   |
|:---|:---|:---|
| C000164452 | UBS Prime Reserves Fund | UPRXX           |

# 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 Prime Reserves Fund

**LEI of Series:** 549300SZFUYVRC9F4568

**EDGAR Series Identifier:** S000052306

**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:** $14353234854.56

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

- **Cash:** $0.00

- **Total Other Assets:** $0.00

- **Total Liabilities:** $45056667.89

- **Net Assets of Series:** $14308178186.67

- **Number of Shares Outstanding (Series):** 14307329388.7500

- **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 | $11397664782.33           | $12492514958.46            | 48.5200%                  | 53.1800%                   |
| 2026-05-04 | $11305274371.21           | $12456929449.21            | 48.1100%                  | 53.0100%                   |
| 2026-05-05 | $11434414306.57           | $12508120497.07            | 48.5500%                  | 53.1100%                   |
| 2026-05-06 | $11398415802.21           | $12492063918.41            | 48.4400%                  | 53.0900%                   |
| 2026-05-07 | $11720397223.61           | $12786998754.21            | 49.1500%                  | 53.6200%                   |
| 2026-05-08 | $11585036458.41           | $12398732366.21            | 48.8800%                  | 52.3100%                   |
| 2026-05-11 | $11125885941.85           | $12448386221.85            | 47.1600%                  | 52.7600%                   |
| 2026-05-12 | $11236749345.50           | $12390349502.90            | 47.4900%                  | 52.3700%                   |
| 2026-05-13 | $11078990541.70           | $12429579173.00            | 46.8000%                  | 52.5100%                   |
| 2026-05-14 | $10933116803.11           | $12380662277.63            | 45.9500%                  | 52.0300%                   |
| 2026-05-15 | $11084922610.33           | $12174529209.54            | 47.1500%                  | 51.7800%                   |
| 2026-05-18 | $10900087745.14           | $12190751353.26            | 46.1900%                  | 51.6600%                   |
| 2026-05-19 | $11342242573.14           | $12200922202.30            | 47.9900%                  | 51.6200%                   |
| 2026-05-20 | $10763124765.72           | $12172352618.72            | 45.7300%                  | 51.7200%                   |
| 2026-05-21 | $10874472886.40           | $12249763842.50            | 46.1100%                  | 51.9400%                   |
| 2026-05-22 | $11147756285.01           | $12293236556.51            | 47.1700%                  | 52.0100%                   |
| 2026-05-26 | $11356186924.86           | $12271831609.86            | 47.9200%                  | 51.7900%                   |
| 2026-05-27 | $11219293926.37           | $12258167174.57            | 47.5400%                  | 51.9400%                   |
| 2026-05-28 | $11040110912.22           | $12181973632.57            | 46.7800%                  | 51.6200%                   |
| 2026-05-29 | $10893842147.18           | $12035797564.65            | 46.4400%                  | 51.3000%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2026-05-01 | 3.8000%             |
| 2026-05-04 | 3.8000%             |
| 2026-05-05 | 3.8000%             |
| 2026-05-06 | 3.7900%             |
| 2026-05-07 | 3.7900%             |
| 2026-05-08 | 3.7800%             |
| 2026-05-11 | 3.7800%             |
| 2026-05-12 | 3.7800%             |
| 2026-05-13 | 3.7800%             |
| 2026-05-14 | 3.7800%             |
| 2026-05-15 | 3.7700%             |
| 2026-05-18 | 3.7700%             |
| 2026-05-19 | 3.7700%             |
| 2026-05-20 | 3.7600%             |
| 2026-05-21 | 3.7600%             |
| 2026-05-22 | 3.7500%             |
| 2026-05-26 | 3.7500%             |
| 2026-05-27 | 3.7600%             |
| 2026-05-28 | 3.7700%             |
| 2026-05-29 | 3.7900%             |

### Daily Net Asset Value per Share (Series)
| Date       | Net Asset Value per Share   |
|:---|:---|
| 2026-05-01 | 0.9999                      |
|  |  |
| 2026-05-04 | 1.0000                      |
|  |  |
| 2026-05-05 | 1.0000                      |
|  |  |
| 2026-05-06 | 1.0000                      |
|  |  |
| 2026-05-07 | 1.0000                      |
|  |  |
| 2026-05-08 | 0.9999                      |
|  |  |
| 2026-05-11 | 1.0000                      |
|  |  |
| 2026-05-12 | 1.0000                      |
|  |  |
| 2026-05-13 | 1.0000                      |
|  |  |
| 2026-05-14 | 1.0000                      |
|  |  |
| 2026-05-15 | 0.9999                      |
|  |  |
| 2026-05-18 | 1.0000                      |
|  |  |
| 2026-05-19 | 1.0000                      |
|  |  |
| 2026-05-20 | 1.0000                      |
|  |  |
| 2026-05-21 | 1.0000                      |
|  |  |
| 2026-05-22 | 0.9999                      |
|  |  |
| 2026-05-26 | 1.0000                      |
|  |  |
| 2026-05-27 | 1.0000                      |
|  |  |
| 2026-05-28 | 1.0000                      |
|  |  |
| 2026-05-29 | 0.9999                      |
|  |  |

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

### Class: Single Class

- **Minimum Initial Investment:** $1000000.00

- **Net Assets of Class:** $14308178186.67

- **Number of Shares Outstanding:** 14307329388.7500

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2026-05-01 | 0.9999          |
|  |  |
| 2026-05-04 | 1.0000          |
|  |  |
| 2026-05-05 | 1.0000          |
|  |  |
| 2026-05-06 | 1.0000          |
|  |  |
| 2026-05-07 | 1.0000          |
|  |  |
| 2026-05-08 | 0.9999          |
|  |  |
| 2026-05-11 | 1.0000          |
|  |  |
| 2026-05-12 | 1.0000          |
|  |  |
| 2026-05-13 | 1.0000          |
|  |  |
| 2026-05-14 | 1.0000          |
|  |  |
| 2026-05-15 | 0.9999          |
|  |  |
| 2026-05-18 | 1.0000          |
|  |  |
| 2026-05-19 | 1.0000          |
|  |  |
| 2026-05-20 | 1.0000          |
|  |  |
| 2026-05-21 | 1.0000          |
|  |  |
| 2026-05-22 | 0.9999          |
|  |  |
| 2026-05-26 | 1.0000          |
|  |  |
| 2026-05-27 | 1.0000          |
|  |  |
| 2026-05-28 | 1.0000          |
|  |  |
| 2026-05-29 | 0.9999          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2026-05-01 | $148787050.79             | $57693642.55            |
| 2026-05-04 | $162953914.13             | $76382524.42            |
| 2026-05-05 | $86187557.41              | $76681393.18            |
| 2026-05-06 | $73868249.93              | $71623924.05            |
| 2026-05-07 | $119418825.15             | $69455685.72            |
| 2026-05-08 | $102511604.54             | $59757805.79            |
| 2026-05-11 | $77292205.78              | $122366611.22           |
| 2026-05-12 | $62116503.75              | $80413990.05            |
| 2026-05-13 | $81630050.16              | $101169694.57           |
| 2026-05-14 | $67975467.51              | $116264694.39           |
| 2026-05-15 | $82922450.11              | $73403794.60            |
| 2026-05-18 | $117448524.81             | $67264263.85            |
| 2026-05-19 | $73748071.47              | $94675435.08            |
| 2026-05-20 | $60233780.38              | $94691860.61            |
| 2026-05-21 | $76838026.14              | $95810100.74            |
| 2026-05-22 | $149704040.56             | $82419339.89            |
| 2026-05-26 | $102848938.90             | $138673562.34           |
| 2026-05-27 | $83320044.56              | $99050558.03            |
| 2026-05-28 | $91689266.55              | $96709479.06            |
| 2026-05-29 | $60537737.26              | $77824143.22            |

**Total Gross Subscriptions (Month):** $1882032309.89

**Total Gross Redemptions (Month):** $1752332503.36

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2026-05-01 | 3.6200%           |
| 2026-05-04 | 3.6200%           |
| 2026-05-05 | 3.6200%           |
| 2026-05-06 | 3.6100%           |
| 2026-05-07 | 3.6100%           |
| 2026-05-08 | 3.6000%           |
| 2026-05-11 | 3.6000%           |
| 2026-05-12 | 3.6000%           |
| 2026-05-13 | 3.6000%           |
| 2026-05-14 | 3.6000%           |
| 2026-05-15 | 3.5900%           |
| 2026-05-18 | 3.5900%           |
| 2026-05-19 | 3.5900%           |
| 2026-05-20 | 3.5800%           |
| 2026-05-21 | 3.5800%           |
| 2026-05-22 | 3.5700%           |
| 2026-05-26 | 3.5700%           |
| 2026-05-27 | 3.5800%           |
| 2026-05-28 | 3.5900%           |
| 2026-05-29 | 3.6100%           |

## 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):** $14353234854.56
- **C.18.a - Value (excl. sponsor support):** $14353234854.56
- **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