# EDGAR Filing Document

**Accession Number:** 0000889512
**File Stem:** 0001193125-25-273529
**Filing Date:** 2025-11
**Character Count:** 7630
**Document Hash:** 543e03706da741f0c7382f62c1332d30
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-25-273529.hdr.sgml**: 20251110

**ACCESSION NUMBER**: 0001193125-25-273529

**CONFORMED SUBMISSION TYPE**: 485BXT

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20251110

**DATE AS OF CHANGE**: 20251110

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** LEGG MASON PARTNERS INSTITUTIONAL TRUST
- **CENTRAL INDEX KEY:** 0000889512

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** MD
- **FISCAL YEAR END:** 0831

**FILING VALUES:**
- **FORM TYPE:** 485BXT
- **SEC ACT:** 1940 Act
- **SEC FILE NUMBER:** 811-06740
- **FILM NUMBER:** 251465006

**BUSINESS ADDRESS:**
- **STREET 1:** LEGG MASON & CO., LLC
- **STREET 2:** 620 EIGHTH AVENUE
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10018
- **BUSINESS PHONE:** 1-877-721-1926

**MAIL ADDRESS:**
- **STREET 1:** LEGG MASON & CO., LLC
- **STREET 2:** 620 EIGHTH AVENUE
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10018

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** CITIFUNDS INSTITUTIONAL TRUST
- **DATE OF NAME CHANGE:** 19981030
**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** LEGG MASON PARTNERS INSTITUTIONAL TRUST
- **CENTRAL INDEX KEY:** 0000889512

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** MD
- **FISCAL YEAR END:** 0831

**FILING VALUES:**
- **FORM TYPE:** 485BXT
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 033-49552
- **FILM NUMBER:** 251465005

**BUSINESS ADDRESS:**
- **STREET 1:** LEGG MASON & CO., LLC
- **STREET 2:** 620 EIGHTH AVENUE
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10018
- **BUSINESS PHONE:** 1-877-721-1926

**MAIL ADDRESS:**
- **STREET 1:** LEGG MASON & CO., LLC
- **STREET 2:** 620 EIGHTH AVENUE
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10018

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** CITIFUNDS INSTITUTIONAL TRUST
- **DATE OF NAME CHANGE:** 19981030

## Series and Classes Contracts Data

### Western Asset Institutional U.S. Treasury Reserves (Series ID: S000008910)

| Class ID   | Class Name                   | Ticker Symbol   |
|:---|:---|:---|
| C000024239 | Institutional Shares         | CIIXX           |
| C000089733 | Investor Shares              | LTRXX           |
| C000091745 | Administrative Shares        | LTAXX           |
| C000266548 | Digital Institutional Shares |  |

**As filed with the U.S. Securities and Exchange Commission on November 10, 2025** 

**Securities Act File No. 033-49552** 

**Investment Company Act File No. 811-06740** 

**UNITED STATES** 

**SECURITIES AND EXCHANGE COMMISSION** 

**Washington, D.C. 20549** 

**FORM N-1A** 

**REGISTRATION STATEMENT** 

***UNDER***

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| | |
|:---|:---|
| ***THE SECURITIES ACT OF 1933*** | ☒ |
| **Pre-Effective Amendment No.** |  |
| **Post-Effective Amendment No. 155** | ☒ |

---

**and/or** 

**REGISTRATION STATEMENT** 

***UNDER***

---

| | |
|:---|:---|
| ***THE INVESTMENT COMPANY ACT OF 1940*** | ☒ |

---

**Amendment No. 161** 

## Legg Mason Partners Institutional Trust\*
**(Exact Name of Registrant as Specified in Charter)** 

**One Madison Avenue** 

**New York, NY 10010** 

**(Address of Principal Executive Offices) (Zip Code)** 

**Registrant's telephone number, including area code: (800) 625-4554** 

---

| | | |
|:---|:---|:---|
| **Name and address of agent for service:** | ***Copy to:*** |  |
| **Marc De Oliveira** | **Bryan Chegwidden, Esq.** | **Adam M. Schlichtmann, Esq.** |
| **Franklin Templeton** | **Ropes & Gray LLP** | **Ropes & Gray LLP** |
| **100 First Stamford Place** | **1211 Avenue of the Americas** | **Prudential Tower, 800 Boylston Street** |
| **Stamford, Connecticut 06902** | **New York, New York 10036** | **Boston, Massachusetts 02199** |

---

**Continuous** 

**(Approximate Date of Proposed Offering)** 

It is proposed that this filing will become effective:

☐ immediately upon filing pursuant to paragraph (b)

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;☒ on December 9, 2025 <u> </u> pursuant to paragraph (b)

☐ 60 days after filing pursuant to paragraph (a)(1)

☐ on<u> </u> pursuant to paragraph (a)(1)

☐ 75 days after filing pursuant to paragraph (a)(2)

☐ on<u> </u> pursuant to paragraph (a)(2) of Rule 485.

If appropriate, check the following box:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;☒ This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

\* This Post-Effective Amendment No. 155 (this "Amendment") to the Registration Statement of Legg Mason Partners Institutional Trust on Form N-1A (the "Registration Statement") is being filed pursuant to Rule 485(b) under the Securities Act of 1933, as amended (the "Securities Act"), solely to designate December 9, 2025 as the new effective date for Post-Effective Amendment No. 154 to the Registration Statement ("Post-Effective Amendment No. 154"), filed pursuant to Rule 485(a) under the Securities Act on September 15, 2025. This Amendment relates solely to Western Asset Institutional U.S. Treasury Reserves and is not intended to amend or supersede any information contained in Post-Effective Amendment No. 154. 

This Amendment incorporates by reference the information contained in Parts A, B and C of [Post-Effective Amendment No. 154](http://www.sec.gov/Archives/edgar/data/889512/000119312525203245/d87127d485apos.htm).

------

**SIGNATURES** 

Pursuant to the requirements of the Securities Act of 1933, as amended (the "Securities Act"), and the Investment Company Act of 1940, as amended, the Registrant, LEGG MASON PARTNERS INSTITUTIONAL TRUST, certifies that it meets all the requirements for the effectiveness of this Post-Effective Amendment to its Registration Statement pursuant to Rule 485(b)(1)(iii) under the Securities Act and has duly caused this Post-Effective Amendment to its Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Baltimore, State of Maryland on this 10th day of November, 2025.

**LEGG MASON PARTNERS INSTITUTIONAL<br>TRUST,** on behalf of its series:<br>

---

| | |
|:---|:---|
| **Western Asset Institutional U.S. Treasury Reserves** | **Western Asset Institutional U.S. Treasury Reserves** |
| By: | /s/ Jane E. Trust |
|  | Jane E. Trust |
|  | President and Chief Executive Officer |

---

WITNESS our hands on the date set forth below.

Pursuant to the requirements of the Securities Act, this Post-Effective Amendment to the Registration Statement has been signed below by the following persons in the capacities indicated below on this 10<sup>th</sup> day of November, 2025.

---

| | |
|:---|:---|
| **Signature** | **Title** |
| /s/ Jane E. Trust<br> Jane E. Trust | President, Chief Executive Officer and Trustee |
| /s/ Christopher Berarducci<br> Christopher Berarducci | Principal Financial Officer and Treasurer |
| /s/ Robert Abeles, Jr.\*<br> Robert Abeles, Jr. | Trustee |
| /s/ Jane F. Dasher\*<br> Jane F. Dasher | Trustee |
| /s/ Anita L. DeFrantz\*<br> Anita L. DeFrantz | Trustee |
| /s/ Susan B. Kerley\*<br> Susan B. Kerley | Trustee |
| /s/ Ronald L. Olson\*<br> Ronald L. Olson | Trustee |
| /s/ Avedick B. Poladian\*<br> Avedick B. Poladian | Trustee |
| /s/ William E.B. Siart\*<br> William E.B. Siart | Trustee |

---

------

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| | |
|:---|:---|
| /s/ Jaynie M. Studenmund\*<br> Jaynie M. Studenmund | Trustee |
| /s/ Peter J. Taylor\*<br> Peter J. Taylor | Trustee |
| /s/ Michael Larson\*<br> Michael Larson | Trustee |

---

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| | |
|:---|:---|
| \*By: | /s/ Jane E. Trust |
|  | Jane E. Trust |

---

\* Attorney in Fact, pursuant to Power of Attorney.