# EDGAR Filing Document

**Accession Number:** 0001107414
**File Stem:** 0001410368-25-021441
**Filing Date:** 2025-11
**Character Count:** 14094
**Document Hash:** a6ee263e2fc432e7ca3776982516a294
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001410368-25-021441.hdr.sgml**: 20251107

**ACCESSION NUMBER**: 0001410368-25-021441

**CONFORMED SUBMISSION TYPE**: N-MFP3

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20251031

**FILED AS OF DATE**: 20251107

**DATE AS OF CHANGE**: 20251107

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** STATE STREET INSTITUTIONAL INVESTMENT TRUST
- **CENTRAL INDEX KEY:** 0001107414

**ORGANIZATION NAME:**
- **EIN:** 046910804
- **STATE OF INCORPORATION:** MA
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** N-MFP3
- **SEC ACT:** 1940 Act
- **SEC FILE NUMBER:** 811-09819
- **FILM NUMBER:** 251461100

**BUSINESS ADDRESS:**
- **STREET 1:** ONE CONGRESS STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02114
- **BUSINESS PHONE:** 6176643920

**MAIL ADDRESS:**
- **STREET 1:** ONE CONGRESS STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02114

## Series and Classes Contracts Data

### State Street Federal Treasury Plus Money Market Fund (Series ID: S000086382)

| Class ID   | Class Name      | Ticker Symbol   |
|:---|:---|:---|
| C000251885 | Advantage Class | ATPXX           |

# Form N-MFP3: Monthly Schedule of Portfolio Holdings

## N-MFP: Filer Information
**Submission Type:** N-MFP3
**CIK:** 0001107414

### General Information

**Report for (YYYY-MM-DD):** 2025-10-31

**Registrant Full Name:** STATE STREET INSTITUTIONAL INVESTMENT TRUST

**CIK Number of Registrant:** 0001107414

**LEI of Registrant:** 549300P1E098W6ES7M39

**Name of Series:** State Street Federal Treasury Plus Money Market Fund

**LEI of Series:** 984500FCIE7E84F01E90

**EDGAR Series Identifier:** S000086382

**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            | SSGA Funds Management, Inc.                     | 801-60103         |
| Independent Public Accountant | Ernst & Young  LLP<br>City: Boston<br>State: MA |  |
| Administrator                 | SSGA Funds Management, Inc.                     |  |
| Transfer Agent                | SS&C GIDS, Inc.<br>CIK: 0000027048              | 084-00448         |

### Fund Characteristics & Assets

- **Securities Act File Number:** 333-30810

- **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?:** No

- **WAM:** 1 days

- **WAL:** 1 days

- **Total Value of Portfolio Securities:** $64368502.02

- **Amortized Cost of Portfolio Securities:** $64368502.02

- **Cash:** $0.00

- **Total Other Assets:** $0.00

- **Total Liabilities:** $269434.40

- **Net Assets of Series:** $64099067.62

- **Number of Shares Outstanding (Series):** 64099052.2000

- **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 (%)   |
|:---|:---|:---|:---|:---|
| 2025-10-01 | $63249094641.34           | $63249094641.34            | 97.5100%                  | 97.5100%                   |
| 2025-10-02 | $63824634970.79           | $63824634970.79            | 97.5300%                  | 97.5300%                   |
| 2025-10-03 | $57355246605.45           | $57355246605.45            | 97.2500%                  | 97.2500%                   |
| 2025-10-06 | $57340706611.81           | $57340706611.81            | 97.2500%                  | 97.2500%                   |
| 2025-10-07 | $56572321150.56           | $56572321150.56            | 97.2100%                  | 97.2100%                   |
| 2025-10-08 | $57506931040.94           | $57506931040.94            | 97.2500%                  | 97.2500%                   |
| 2025-10-09 | $55367113840.98           | $55367113840.98            | 97.1500%                  | 97.1500%                   |
| 2025-10-10 | $55318327687.44           | $55318327687.44            | 97.1300%                  | 97.1300%                   |
| 2025-10-13 | $0.00                     | $0.00                      | 0.0000%                   | 0.0000%                    |
| 2025-10-14 | $55421912859.54           | $55421912859.54            | 97.1400%                  | 97.1400%                   |
| 2025-10-15 | $56001789216.15           | $56001789216.15            | 97.1700%                  | 97.1700%                   |
| 2025-10-16 | $54892830326.09           | $54892830326.09            | 97.1100%                  | 97.1100%                   |
| 2025-10-17 | $53953144008.21           | $53953144008.21            | 97.0500%                  | 97.0500%                   |
| 2025-10-20 | $54928741467.33           | $55038741467.33            | 97.1000%                  | 97.3000%                   |
| 2025-10-21 | $54752680460.41           | $54862680460.41            | 97.0900%                  | 97.2900%                   |
| 2025-10-22 | $54477672850.79           | $54707672850.79            | 97.0800%                  | 97.4900%                   |
| 2025-10-23 | $52684659636.57           | $52794659636.57            | 96.9800%                  | 97.1800%                   |
| 2025-10-24 | $53015897710.44           | $53015897710.44            | 97.1800%                  | 97.1800%                   |
| 2025-10-27 | $53596672413.59           | $53596672413.59            | 97.2100%                  | 97.2100%                   |
| 2025-10-28 | $53817628518.11           | $53817628518.11            | 97.2200%                  | 97.2200%                   |
| 2025-10-29 | $53731917801.24           | $53731917801.24            | 97.2100%                  | 97.2100%                   |
| 2025-10-30 | $50454100160.72           | $50454100160.72            | 97.0300%                  | 97.0300%                   |
| 2025-10-31 | $50231182458.02           | $50231182458.02            | 97.2000%                  | 97.2000%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2025-10-01 | 4.1700%             |
| 2025-10-02 | 4.1700%             |
| 2025-10-03 | 4.1700%             |
| 2025-10-06 | 4.1600%             |
| 2025-10-07 | 4.1600%             |
| 2025-10-08 | 4.1500%             |
| 2025-10-09 | 4.1500%             |
| 2025-10-10 | 4.1300%             |
| 2025-10-13 | 0.0000%             |
| 2025-10-14 | 4.1400%             |
| 2025-10-15 | 4.1400%             |
| 2025-10-16 | 4.1400%             |
| 2025-10-17 | 4.1500%             |
| 2025-10-20 | 4.1500%             |
| 2025-10-21 | 4.1400%             |
| 2025-10-22 | 4.1400%             |
| 2025-10-23 | 4.1400%             |
| 2025-10-24 | 4.1300%             |
| 2025-10-27 | 4.1300%             |
| 2025-10-28 | 4.1300%             |
| 2025-10-29 | 4.1300%             |
| 2025-10-30 | 4.1200%             |
| 2025-10-31 | 4.1000%             |

### Daily Net Asset Value per Share (Series)
| Date       | Net Asset Value per Share   |
|:---|:---|
| 2025-10-01 | 1.0002                      |
|  |  |
| 2025-10-02 | 1.0002                      |
|  |  |
| 2025-10-03 | 1.0002                      |
|  |  |
| 2025-10-06 | 1.0002                      |
|  |  |
| 2025-10-07 | 1.0002                      |
|  |  |
| 2025-10-08 | 1.0002                      |
|  |  |
| 2025-10-09 | 1.0001                      |
|  |  |
| 2025-10-10 | 1.0002                      |
|  |  |
| 2025-10-13 | 0.0000                      |
|  |  |
| 2025-10-14 | 1.0002                      |
|  |  |
| 2025-10-15 | 1.0001                      |
|  |  |
| 2025-10-16 | 1.0002                      |
|  |  |
| 2025-10-17 | 1.0001                      |
|  |  |
| 2025-10-20 | 1.0002                      |
|  |  |
| 2025-10-21 | 1.0002                      |
|  |  |
| 2025-10-22 | 1.0002                      |
|  |  |
| 2025-10-23 | 1.0001                      |
|  |  |
| 2025-10-24 | 1.0002                      |
|  |  |
| 2025-10-27 | 1.0002                      |
|  |  |
| 2025-10-28 | 1.0002                      |
|  |  |
| 2025-10-29 | 1.0001                      |
|  |  |
| 2025-10-30 | 1.0002                      |
|  |  |
| 2025-10-31 | 1.0002                      |
|  |  |

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

### Class: Advantage Class

- **Minimum Initial Investment:** $1000000.00

- **Net Assets of Class:** $64099067.62

- **Number of Shares Outstanding:** 64099052.2000

- **Expense Reimbursement/Waiver:** 5186.00

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2025-10-01 | 1.0002          |
|  |  |
| 2025-10-02 | 1.0002          |
|  |  |
| 2025-10-03 | 1.0002          |
|  |  |
| 2025-10-06 | 1.0002          |
|  |  |
| 2025-10-07 | 1.0002          |
|  |  |
| 2025-10-08 | 1.0002          |
|  |  |
| 2025-10-09 | 1.0001          |
|  |  |
| 2025-10-10 | 1.0002          |
|  |  |
| 2025-10-13 | 0.0000          |
|  |  |
| 2025-10-14 | 1.0002          |
|  |  |
| 2025-10-15 | 1.0001          |
|  |  |
| 2025-10-16 | 1.0002          |
|  |  |
| 2025-10-17 | 1.0001          |
|  |  |
| 2025-10-20 | 1.0002          |
|  |  |
| 2025-10-21 | 1.0002          |
|  |  |
| 2025-10-22 | 1.0002          |
|  |  |
| 2025-10-23 | 1.0001          |
|  |  |
| 2025-10-24 | 1.0002          |
|  |  |
| 2025-10-27 | 1.0002          |
|  |  |
| 2025-10-28 | 1.0002          |
|  |  |
| 2025-10-29 | 1.0001          |
|  |  |
| 2025-10-30 | 1.0002          |
|  |  |
| 2025-10-31 | 1.0002          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2025-10-01 | $281927.86                | $154029.47              |
| 2025-10-02 | $300362.76                | $235968.84              |
| 2025-10-03 | $180048.78                | $396852.24              |
| 2025-10-06 | $1950000.00               | $28340.00               |
| 2025-10-07 | $822326.83                | $459440.94              |
| 2025-10-08 | $910850.00                | $47277.50               |
| 2025-10-09 | $808000.00                | $174366.67              |
| 2025-10-10 | $1341783.56               | $383326.03              |
| 2025-10-13 | $0.00                     | $0.00                   |
| 2025-10-14 | $13333.33                 | $851704.51              |
| 2025-10-15 | $445100.00                | $1433853.86             |
| 2025-10-16 | $372900.00                | $124800.72              |
| 2025-10-17 | $1399.59                  | $278052.26              |
| 2025-10-20 | $1396800.00               | $326286.00              |
| 2025-10-21 | $810425.00                | $386886.93              |
| 2025-10-22 | $481733.37                | $312645.30              |
| 2025-10-23 | $51500.00                 | $183500.00              |
| 2025-10-24 | $90404.68                 | $95081.52               |
| 2025-10-27 | $150500.00                | $2061615.57             |
| 2025-10-28 | $1068730.61               | $2130577.12             |
| 2025-10-29 | $5500.00                  | $163764.15              |
| 2025-10-30 | $662000.00                | $377120.00              |
| 2025-10-31 | $392516.48                | $1060674.34             |

**Total Gross Subscriptions (Month):** $12538142.85

**Total Gross Redemptions (Month):** $11666163.97

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2025-10-01 | 3.7800%           |
| 2025-10-02 | 3.7800%           |
| 2025-10-03 | 3.7800%           |
| 2025-10-06 | 3.7700%           |
| 2025-10-07 | 3.7700%           |
| 2025-10-08 | 3.7600%           |
| 2025-10-09 | 3.7600%           |
| 2025-10-10 | 3.7400%           |
| 2025-10-13 | 0.0000%           |
| 2025-10-14 | 3.7500%           |
| 2025-10-15 | 3.7500%           |
| 2025-10-16 | 3.7500%           |
| 2025-10-17 | 3.7600%           |
| 2025-10-20 | 3.7600%           |
| 2025-10-21 | 3.7500%           |
| 2025-10-22 | 3.7500%           |
| 2025-10-23 | 3.7500%           |
| 2025-10-24 | 3.7400%           |
| 2025-10-27 | 3.7400%           |
| 2025-10-28 | 3.7400%           |
| 2025-10-29 | 3.7400%           |
| 2025-10-30 | 3.7300%           |
| 2025-10-31 | 3.7100%           |

**Beneficial/Record Owner Categories**
| Category      | Other Category   | Record Owner %   | Beneficial Owner %   |
|:---|:---|:---|:---|
| Broker-dealer |  | 99.8400%         | 0.0000%              |

## Part C: Schedule of Portfolio Securities

### Security 1: State Street Treasury Plus Money Market Portfolio

- **C.1 - Title:** State Street Treasury Plus Money Market Portfolio
- **C.6 - Investment Category:** Investment Company
- **Identifiers:** C.3 - CUSIP: FSSgAK1AW, C.3 - LEI: N/A, C.5 - Other ID: FSSgAK1AW
- **C.18 - Value (incl. sponsor support):** $64368502.02
- **C.18.a - Value (excl. sponsor support):** $64368502.02
- **C.19 - Percentage of Net Assets:** 100.0000%
- **C.17 - Yield as of Reporting Date:** 0.0000%
- **C.11 - Maturity Date (WAM):** 2025-11-03
- **C.12 - Maturity Date (WAL):** 2025-11-03
- **C.13 - Final Legal Maturity Date:** 2025-11-03
- **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:** STATE STREET INSTITUTIONAL INVESTMENT TRUST

**Date:** 2025-11-07

**By:** /s/ Chad Hallett

**Name of Signing Officer:** Chad Hallett

**Title of Signing Officer:** Deputy Treasurer