# EDGAR Filing Document

**Accession Number:** 0000804239
**File Stem:** 0001104659-25-105627
**Filing Date:** 2025-11
**Character Count:** 12192
**Document Hash:** 298475fec5114f9eb17cea4d70558a60
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-25-105627.hdr.sgml**: 20251103

**ACCESSION NUMBER**: 0001104659-25-105627

**CONFORMED SUBMISSION TYPE**: 497

**PUBLIC DOCUMENT COUNT**: 4

**FILED AS OF DATE**: 20251103

**DATE AS OF CHANGE**: 20251103

**EFFECTIVENESS DATE**: 20251103

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** SEI INSTITUTIONAL MANAGED TRUST
- **CENTRAL INDEX KEY:** 0000804239

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** PA
- **FISCAL YEAR END:** 0930

**FILING VALUES:**
- **FORM TYPE:** 497
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 033-09504
- **FILM NUMBER:** 251445014

**BUSINESS ADDRESS:**
- **STREET 1:** 2 OLIVER ST
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02109
- **BUSINESS PHONE:** 8003455734

**MAIL ADDRESS:**
- **STREET 1:** SEI INVESTMENTS
- **STREET 2:** 1 FREEDOM VALLEY DRIVE
- **CITY:** OAKS
- **STATE:** PA
- **ZIP:** 19456

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** TRUSTFUNDS INSTITUTIONAL MANAGED TRUST
- **DATE OF NAME CHANGE:** 19890509

## Series and Classes Contracts Data

### SIMT HIGH YIELD BOND FUND (Series ID: S000006673)

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|  |  |  |
|:---|:---|:---|
| Class Name | Ticker Symbol | Class ID   |
| CLASS F    | SHYAX         | C000018196 |
| Class I    | SEIYX         | C000036884 |
| Class Y    | SIYYX         | C000147389 |

---

## Series and Classes Contracts Data

### SIMT HIGH YIELD BOND FUND (Series ID: S000006673)

| Class ID   | Class Name   | Ticker Symbol   |
|:---|:---|:---|
| C000018196 | CLASS F      | SHYAX           |
| C000036884 | Class I      | SEIYX           |
| C000147389 | Class Y      | SIYYX           |

SEI INSTITUTIONAL MANAGED TRUST

High Yield Bond Fund<br>(the "Fund")

Supplement Dated November 3, 2025<br>to the Class F Shares and Class Y Shares Prospectuses, each dated January 31, 2025, as amended February 26, 2025, <br>May 9, 2025, May 29, 2025 and July 1, 2025 (the "Prospectuses")

This Supplement provides new and additional information beyond that contained in the Prospectuses and should be read in conjunction with such Prospectuses.

*The Prospectuses are hereby amended and supplemented to reflect the following changes to the Fund.*

Change in Portfolio Management of the Fund

*T. Rowe Price Associates, Inc. no longer serves as a sub-adviser to the Fund. As such, all references to T. Rowe Price Associates, Inc. are hereby deleted from the Prospectuses.*

*Additionally, Blackstone Credit Systematic Strategies LLC is added as a sub-adviser to the Fund. Accordingly, the Prospectuses are updated as follows:*

*In the Fund Summary for the Fund, under the heading titled "Management," in the chart under the sub-heading titled "Sub-Advisers and Portfolio Managers," the following text is hereby added in the appropriate alphabetical order thereof:*

---

| | | | |
|:---|:---|:---|:---|
| Sub-Adviser | Portfolio Manager | Experience <br>with<br>the Fund | Title with Sub-Adviser |
| Blackstone Credit Systematic <br>Strategies LLC | Adam Dwinells | Since 2025 | Global Head of Corporate Bond Strategies, <br>Technology, and Operations for Liquid <br>Credit Strategies |

---

*In addition, under the section titled "Sub-Advisers," under the heading titled "Sub-Advisers and Portfolio Managers," under the sub-heading titled "High Yield Bond Fund," the following text is hereby added in the appropriate alphabetical order thereof:*

Blackstone Credit Systematic Strategies LLC: Blackstone Credit Systematic Strategies LLC, also known as Blackstone Corporate Bond Strategies (BCBS), located at 345 Park Avenue, 31st Floor, New York, New York 10154, serves as a Sub-Adviser to the High Yield Bond Fund. A team of investment professionals manages the portion of the High Yield Bond Fund's assets allocated to BCBS. Adam Dwinells, Senior Managing Director, Global Head of Corporate Bond Strategies, Technology, and Operations for Liquid Credit Strategies is the lead portfolio manager and has been with the team since 2005.

*There are no other changes to the Prospectuses.*

PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE

SEI-F-1624 (11/25)

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SEI INSTITUTIONAL MANAGED TRUST

High Yield Bond Fund<br>(the "Fund")

Supplement Dated November 3, 2025<br>to the Class I Shares Prospectus, dated January 31, 2025, as amended February 26, 2025, May 9, 2025 and <br>July 1, 2025 (the "Prospectus")

This Supplement provides new and additional information beyond that contained in the Prospectus and should be read in conjunction with such Prospectus.

*The Prospectus is hereby amended and supplemented to reflect the following changes to the Fund.*

Change in Portfolio Management of the Fund

*T. Rowe Price Associates, Inc. no longer serves as a sub-adviser to the Fund. As such, all references to T. Rowe Price Associates, Inc. are hereby deleted from the Prospectus.*

*Additionally, Blackstone Credit Systematic Strategies LLC is added as a sub-adviser to the Fund. Accordingly, the Prospectus is updated as follows:*

*In the Fund Summary for the Fund, under the heading titled "Management," in the chart under the sub-heading titled "Sub-Advisers and Portfolio Managers," the following text is hereby added in the appropriate alphabetical order thereof:*

---

| | | | |
|:---|:---|:---|:---|
| Sub-Adviser | Portfolio Manager | Experience <br>with <br>the Fund | Title with Sub-Adviser |
| Blackstone Credit Systematic Strategies LLC | Adam Dwinells | Since 2025 | Global Head of Corporate Bond Strategies, Technology, and Operations for Liquid Credit Strategies |

---

*In addition, under the section titled "Sub-Advisers," under the heading titled "Sub-Advisers and Portfolio Managers," under the sub-heading titled "High Yield Bond Fund," the following text is hereby added in the appropriate alphabetical order thereof:*

Blackstone Credit Systematic Strategies LLC: Blackstone Credit Systematic Strategies LLC, also known as Blackstone Corporate Bond Strategies (BCBS), located at 345 Park Avenue, 31st Floor, New York, New York 10154, serves as a Sub-Adviser to the High Yield Bond Fund. A team of investment professionals manages the portion of the High Yield Bond Fund's assets allocated to BCBS. Adam Dwinells, Senior Managing Director, Global Head of Corporate Bond Strategies, Technology, and Operations for Liquid Credit Strategies is the lead portfolio manager and has been with the team since 2005.

*There are no other changes to the Prospectus.*

PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE

SEI-F-1625 (11/25)

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SEI INSTITUTIONAL MANAGED TRUST

High Yield Bond Fund<br>(the "Fund")

Supplement Dated November 3, 2025<br>to the Statement of Additional Information (the "SAI") dated January 31, 2025, as amended <br>February 26, 2025, April 11, 2025, May 9, 2025, May 29, 2025, May 30, 2025 and July 1, 2025

This Supplement provides new and additional information beyond that contained in the SAI and should be read in conjunction with such SAI.

*The SAI is hereby amended and supplemented to reflect the following changes to the Fund.*

Change in Portfolio Management of the Fund

*T. Rowe Price Associates, Inc. no longer serves as a sub-adviser to the Fund. As such, all references to T. Rowe Price Associates, Inc. are hereby deleted from the SAI.*

*Additionally, Blackstone Credit Systematic Strategies LLC is added as a sub-adviser to the Fund. Accordingly, the SAI is updated as follows:*

*On the cover page of the SAI, "Blackstone Credit Systematic Strategies LLC" is hereby added in the appropriate alphabetical order thereof.*

*Under the section titled "The Adviser and Sub-Advisers," under the heading titled "The Sub-Advisers," the following text is hereby added in the appropriate alphabetical order thereof:*

BLACKSTONE CREDIT SYSTEMATIC STRATEGIES LLC—Blackstone Credit Systematic Strategies LLC ("BCBS") serves as a Sub-Adviser to a portion of the assets of the High Yield Bond Fund. BCBS is an investment adviser that is part of the Blackstone Credit & Insurance ("BXCI") business unit, one of the world's leading credit investors. Blackstone Inc. is the ultimate parent company of BCBS (together with its affiliates, including BCBS, "Blackstone" or the "Firm") manages global investment strategies focused on real estate, private equity, credit, infrastructure, life sciences, growth equity, secondaries and hedge funds. As of September 30, 2025, Blackstone has total assets under management of more than $1.2 trillion including $321 billion of investor capital in real estate funds, $396 billion in private equity funds, $432 billion in credit & insurance businesses, and $93 billion in multi-asset investing.

*In addition, under the same section, under the heading titled "Portfolio Management," the following text is hereby added in the appropriate alphabetical order thereof:*

BCBS

*Compensation.* SIMC pays BCBS a fee based on the assets under management of the High Yield Bond Fund as set forth in an investment sub-advisory agreement between BCBS and SIMC. BCBS pays its investment professionals out of its total revenues and other resources, including the sub-advisory fees earned with respect to the High Yield Bond Fund. The following information relates to the period ended September 30, 2025.

Blackstone believes that its compensation approach, which includes discretionary cash and equity bonuses, greatly aligns the goals of its investment professionals with those of its investors and is designed to attract and retain top talent. Blackstone professionals' compensation may include a base salary, a discretionary bonus, and participation in carried interest pools from other parts of Blackstone. Compensation is determined based on individual performance, overall Firm performance, the performance of the relevant Blackstone business unit and current market conditions.

*Ownership of Fund Shares.* As of September 30, 2025, BCBS's portfolio managers did not beneficially own any shares of the High Yield Bond Fund.

*Other Accounts.* As of September 30, 2025, in addition to the High Yield Bond Fund, BCBS's portfolio managers were responsible for the day-to-day management of certain other accounts, as follows:

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| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
| | Registered Investment <br>Companies | Registered Investment <br>Companies | Other Pooled <br>Investment Vehicles | Other Pooled <br>Investment Vehicles | Other Accounts | Other Accounts |
| Portfolio Manager | Number of <br>Accounts | Total Assets<br>(in billions) | Number of <br>Accounts | Total Assets<br>(in billions) | Number of <br>Accounts | Total Assets<br>(in billions) |
| Adam Dwinells | 0 | $0 | 5 | $4.2 | 24 | $29.4 |

---

No account listed above is subject to a performance-based advisory fee.

*Conflicts of Interest.* Blackstone has implemented policies and processes to mitigate the effects of any potential conflicts of interest and has established a governance committee to oversee investment allocations and conflicts. Information walls (administered by Blackstone's legal and compliance personnel) exist to prevent the inappropriate flow of information between business groups within

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Blackstone. From time to time, BXCI co-invests alongside other Blackstone groups or in different levels of the capital structure than other Blackstone clients. Blackstone has processes in place to manage these conflicts, which may include review by firmwide or BXCI internal vetting groups or conflicts committees. Blackstone may mitigate conflicts by relying on third parties to validate price and terms for affiliated or portfolio company deals and future voting decisions. Where appropriate under the facts and circumstances of a particular investment, Blackstone may also seek client consent before committing to a transaction.

With respect to investment opportunities and BCBS's allocation policies, it is BCBS's policy and practice to allocate fairly and equitably among clients so as not to advantage one account over another. Conflicts of interest are discussed in greater detail in the BCBS Form ADV.

*There are no other changes to the SAI.*

PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE

SEI-F-1626 (11/25)

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