# EDGAR Filing Document

**Accession Number:** 0001107414
**File Stem:** 0001410368-26-000310
**Filing Date:** 2026-1
**Character Count:** 13735
**Document Hash:** d138cacdcecb7b5b3f28907f2f1e84c2
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001410368-26-000310.hdr.sgml**: 20260108

**ACCESSION NUMBER**: 0001410368-26-000310

**CONFORMED SUBMISSION TYPE**: N-MFP3

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20251231

**FILED AS OF DATE**: 20260108

**DATE AS OF CHANGE**: 20260108

**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:** 26517998

**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 Government Money Market Fund (Series ID: S000086383)

| Class ID   | Class Name      | Ticker Symbol   |
|:---|:---|:---|
| C000251886 | Advantage Class | AGFXX           |

# 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):** 2025-12-31

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

**CIK Number of Registrant:** 0001107414

**LEI of Registrant:** 549300P1E098W6ES7M39

**Name of Series:** State Street Federal Government Money Market Fund

**LEI of Series:** 98450099C3D5363FC713

**EDGAR Series Identifier:** S000086383

**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:** $164407731.04

- **Amortized Cost of Portfolio Securities:** $164407731.04

- **Cash:** $0.00

- **Total Other Assets:** $0.00

- **Total Liabilities:** $686389.28

- **Net Assets of Series:** $163721341.76

- **Number of Shares Outstanding (Series):** 163721161.3700

- **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 (%)   |
|:---|:---|:---|:---|:---|
| 2025-12-01 | $189570434837.93          | $191517364659.65           | 84.5900%                  | 85.4600%                   |
| 2025-12-02 | $188016626006.48          | $189463702181.58           | 84.4800%                  | 85.1300%                   |
| 2025-12-03 | $189034811819.33          | $190481965675.59           | 84.5500%                  | 85.1900%                   |
| 2025-12-04 | $188712066842.10          | $190159410579.50           | 84.4300%                  | 85.0800%                   |
| 2025-12-05 | $181329277809.99          | $182776801226.59           | 83.8900%                  | 84.5600%                   |
| 2025-12-08 | $181597140069.43          | $183401051038.83           | 83.9100%                  | 84.7500%                   |
| 2025-12-09 | $189230440291.48          | $191534406704.20           | 84.2700%                  | 85.2900%                   |
| 2025-12-10 | $185756379801.05          | $187560837729.16           | 84.2100%                  | 85.0300%                   |
| 2025-12-11 | $190375986149.02          | $193045605501.86           | 84.3500%                  | 85.5300%                   |
| 2025-12-12 | $191721249420.08          | $194276054602.09           | 84.2500%                  | 85.3700%                   |
| 2025-12-15 | $187963039692.65          | $189768244227.53           | 84.2700%                  | 85.0800%                   |
| 2025-12-16 | $185376338552.98          | $187181653575.66           | 84.0100%                  | 84.8300%                   |
| 2025-12-17 | $186684911228.09          | $188490570911.37           | 84.0700%                  | 84.8800%                   |
| 2025-12-18 | $184176678853.52          | $185982369276.28           | 83.7300%                  | 84.5500%                   |
| 2025-12-19 | $177352668992.23          | $179158561283.03           | 83.1900%                  | 84.0400%                   |
| 2025-12-22 | $183022182946.11          | $185949646455.00           | 83.6400%                  | 84.9700%                   |
| 2025-12-23 | $184759013901.45          | $187686621926.16           | 83.7700%                  | 85.0900%                   |
| 2025-12-24 | $180766718870.20          | $184194731754.29           | 83.4600%                  | 85.0400%                   |
| 2025-12-26 | $182995199599.81          | $186870744397.41           | 83.6200%                  | 85.3900%                   |
| 2025-12-29 | $186951656501.58          | $190924925275.20           | 83.9100%                  | 85.6900%                   |
| 2025-12-30 | $185556131306.29          | $189914759238.45           | 83.6800%                  | 85.6500%                   |
| 2025-12-31 | $189677429813.63          | $193087179809.97           | 84.3400%                  | 85.8600%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2025-12-01 | 4.0500%             |
| 2025-12-02 | 4.0500%             |
| 2025-12-03 | 4.0500%             |
| 2025-12-04 | 4.0400%             |
| 2025-12-05 | 4.0000%             |
| 2025-12-08 | 3.9900%             |
| 2025-12-09 | 3.9800%             |
| 2025-12-10 | 3.9800%             |
| 2025-12-11 | 3.9700%             |
| 2025-12-12 | 3.9000%             |
| 2025-12-15 | 3.8900%             |
| 2025-12-16 | 3.8700%             |
| 2025-12-17 | 3.8500%             |
| 2025-12-18 | 3.8400%             |
| 2025-12-19 | 3.8400%             |
| 2025-12-22 | 3.8300%             |
| 2025-12-23 | 3.8300%             |
| 2025-12-24 | 3.8300%             |
| 2025-12-26 | 3.8400%             |
| 2025-12-29 | 3.8400%             |
| 2025-12-30 | 3.8500%             |
| 2025-12-31 | 3.8600%             |

### Daily Net Asset Value per Share (Series)
| Date       | Net Asset Value per Share   |
|:---|:---|
| 2025-12-01 | 1.0002                      |
|  |  |
| 2025-12-02 | 1.0002                      |
|  |  |
| 2025-12-03 | 1.0002                      |
|  |  |
| 2025-12-04 | 1.0002                      |
|  |  |
| 2025-12-05 | 1.0002                      |
|  |  |
| 2025-12-08 | 1.0002                      |
|  |  |
| 2025-12-09 | 1.0002                      |
|  |  |
| 2025-12-10 | 1.0003                      |
|  |  |
| 2025-12-11 | 1.0003                      |
|  |  |
| 2025-12-12 | 1.0003                      |
|  |  |
| 2025-12-15 | 1.0003                      |
|  |  |
| 2025-12-16 | 1.0003                      |
|  |  |
| 2025-12-17 | 1.0003                      |
|  |  |
| 2025-12-18 | 1.0003                      |
|  |  |
| 2025-12-19 | 1.0003                      |
|  |  |
| 2025-12-22 | 1.0003                      |
|  |  |
| 2025-12-23 | 1.0003                      |
|  |  |
| 2025-12-24 | 1.0003                      |
|  |  |
| 2025-12-26 | 1.0003                      |
|  |  |
| 2025-12-29 | 1.0003                      |
|  |  |
| 2025-12-30 | 1.0003                      |
|  |  |
| 2025-12-31 | 1.0002                      |
|  |  |

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

### Class: Advantage Class

- **Minimum Initial Investment:** $1000000.00

- **Net Assets of Class:** $163721341.76

- **Number of Shares Outstanding:** 163721161.3700

- **Expense Reimbursement/Waiver:** 9737.00

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2025-12-01 | 1.0002          |
|  |  |
| 2025-12-02 | 1.0002          |
|  |  |
| 2025-12-03 | 1.0002          |
|  |  |
| 2025-12-04 | 1.0002          |
|  |  |
| 2025-12-05 | 1.0002          |
|  |  |
| 2025-12-08 | 1.0002          |
|  |  |
| 2025-12-09 | 1.0002          |
|  |  |
| 2025-12-10 | 1.0003          |
|  |  |
| 2025-12-11 | 1.0003          |
|  |  |
| 2025-12-12 | 1.0003          |
|  |  |
| 2025-12-15 | 1.0003          |
|  |  |
| 2025-12-16 | 1.0003          |
|  |  |
| 2025-12-17 | 1.0003          |
|  |  |
| 2025-12-18 | 1.0003          |
|  |  |
| 2025-12-19 | 1.0003          |
|  |  |
| 2025-12-22 | 1.0003          |
|  |  |
| 2025-12-23 | 1.0003          |
|  |  |
| 2025-12-24 | 1.0003          |
|  |  |
| 2025-12-26 | 1.0003          |
|  |  |
| 2025-12-29 | 1.0003          |
|  |  |
| 2025-12-30 | 1.0003          |
|  |  |
| 2025-12-31 | 1.0002          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2025-12-01 | $1086920.31               | $161634.22              |
| 2025-12-02 | $1250210.73               | $1177396.34             |
| 2025-12-03 | $956238.00                | $334370.88              |
| 2025-12-04 | $87623.00                 | $425541.34              |
| 2025-12-05 | $666579.98                | $501541.43              |
| 2025-12-08 | $8546901.25               | $2477995.81             |
| 2025-12-09 | $1578026.08               | $617159.95              |
| 2025-12-10 | $253880.00                | $790281.72              |
| 2025-12-11 | $1505100.00               | $252266.21              |
| 2025-12-12 | $1922526.26               | $452126.68              |
| 2025-12-15 | $2270087.50               | $376761.92              |
| 2025-12-16 | $343091.67                | $458718.72              |
| 2025-12-17 | $435250.00                | $66181.18               |
| 2025-12-18 | $1131430.48               | $802352.40              |
| 2025-12-19 | $752570.00                | $237496.91              |
| 2025-12-22 | $682768.68                | $677293.05              |
| 2025-12-23 | $2004555.00               | $5010291.93             |
| 2025-12-24 | $1084600.00               | $453575.00              |
| 2025-12-26 | $127008.94                | $432140.89              |
| 2025-12-29 | $594770.39                | $1484920.95             |
| 2025-12-30 | $736400.00                | $1595829.03             |
| 2025-12-31 | $709000.00                | $1141179.08             |

**Total Gross Subscriptions (Month):** $28725538.27

**Total Gross Redemptions (Month):** $19927055.64

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2025-12-01 | 3.6600%           |
| 2025-12-02 | 3.6600%           |
| 2025-12-03 | 3.6600%           |
| 2025-12-04 | 3.6500%           |
| 2025-12-05 | 3.6100%           |
| 2025-12-08 | 3.6000%           |
| 2025-12-09 | 3.5900%           |
| 2025-12-10 | 3.5900%           |
| 2025-12-11 | 3.5800%           |
| 2025-12-12 | 3.5100%           |
| 2025-12-15 | 3.5000%           |
| 2025-12-16 | 3.4800%           |
| 2025-12-17 | 3.4600%           |
| 2025-12-18 | 3.4500%           |
| 2025-12-19 | 3.4500%           |
| 2025-12-22 | 3.4400%           |
| 2025-12-23 | 3.4400%           |
| 2025-12-24 | 3.4400%           |
| 2025-12-26 | 3.4500%           |
| 2025-12-29 | 3.4500%           |
| 2025-12-30 | 3.4600%           |
| 2025-12-31 | 3.4700%           |

**Beneficial/Record Owner Categories**
| Category      | Other Category   | Record Owner %   | Beneficial Owner %   |
|:---|:---|:---|:---|
| Broker-dealer |  | 99.9300%         | 0.0000%              |

## Part C: Schedule of Portfolio Securities

### Security 1: State Street U.S. Government Money Market Portfolio

- **C.1 - Title:** State Street U.S. Government Money Market Portfolio
- **C.6 - Investment Category:** Investment Company
- **Identifiers:** C.3 - CUSIP: FSSgAK1AV, C.3 - LEI: N/A, C.5 - Other ID: FSSgAK1AV
- **C.18 - Value (incl. sponsor support):** $164407731.04
- **C.18.a - Value (excl. sponsor support):** $164407731.04
- **C.19 - Percentage of Net Assets:** 100.0000%
- **C.17 - Yield as of Reporting Date:** 0.0000%
- **C.11 - Maturity Date (WAM):** 2026-01-02
- **C.12 - Maturity Date (WAL):** 2026-01-02
- **C.13 - Final Legal Maturity Date:** 2026-01-02
- **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:** 2026-01-08

**By:** /s/ Chad Hallett

**Name of Signing Officer:** Chad Hallett

**Title of Signing Officer:** Deputy Treasurer