# EDGAR Filing Document

**Accession Number:** 0001107414
**File Stem:** 0001410368-26-000313
**Filing Date:** 2026-1
**Character Count:** 13836
**Document Hash:** d05cfeeea930c088a2af2f22bae26842
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001410368-26-000313.hdr.sgml**: 20260108

**ACCESSION NUMBER**: 0001410368-26-000313

**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:** 26517999

**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 Treasury Obligations Money Market Fund (Series ID: S000058519)

| Class ID   | Class Name                                          | Ticker Symbol   |
|:---|:---|:---|
| C000192374 | State Street Treasury Obligations Money Market Fund | TAQXX           |

# 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 Treasury Obligations Money Market Fund

**LEI of Series:** 549300Q6TZ3O71NFFG47

**EDGAR Series Identifier:** S000058519

**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:** $6379070270.84

- **Amortized Cost of Portfolio Securities:** $6379070270.84

- **Cash:** $0.00

- **Total Other Assets:** $0.00

- **Total Liabilities:** $21992786.47

- **Net Assets of Series:** $6357077484.37

- **Number of Shares Outstanding (Series):** 6357150644.5700

- **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 | $64839915080.46           | $64839915080.46            | 98.4900%                  | 98.4900%                   |
| 2025-12-02 | $66950837842.24           | $66950837842.24            | 98.5400%                  | 98.5400%                   |
| 2025-12-03 | $64241918097.98           | $64241918097.98            | 98.4700%                  | 98.4700%                   |
| 2025-12-04 | $63384249660.19           | $63384249660.19            | 98.4500%                  | 98.4500%                   |
| 2025-12-05 | $66418461601.25           | $66418461601.25            | 98.5000%                  | 98.5000%                   |
| 2025-12-08 | $66963879067.78           | $66963879067.78            | 98.5200%                  | 98.5200%                   |
| 2025-12-09 | $67394872328.88           | $68394872328.88            | 97.1100%                  | 98.5500%                   |
| 2025-12-10 | $66400446596.91           | $66400446596.91            | 98.5000%                  | 98.5000%                   |
| 2025-12-11 | $66927870085.21           | $67547870085.21            | 97.7900%                  | 98.7000%                   |
| 2025-12-12 | $66707137924.47           | $66957137924.47            | 98.1300%                  | 98.5000%                   |
| 2025-12-15 | $68080323010.14           | $68080323010.14            | 98.5300%                  | 98.5300%                   |
| 2025-12-16 | $70962724744.52           | $70962724744.52            | 98.5900%                  | 98.5900%                   |
| 2025-12-17 | $70496750413.72           | $70496750413.72            | 98.5800%                  | 98.5800%                   |
| 2025-12-18 | $68037043056.68           | $68037043056.68            | 98.5200%                  | 98.5200%                   |
| 2025-12-19 | $68727918102.89           | $68727918102.89            | 98.5200%                  | 98.5200%                   |
| 2025-12-22 | $69767905995.79           | $69767905995.79            | 98.5500%                  | 98.5500%                   |
| 2025-12-23 | $68661288035.41           | $68661288035.41            | 98.5300%                  | 98.5300%                   |
| 2025-12-24 | $69269353407.31           | $69769353407.31            | 98.5300%                  | 99.2400%                   |
| 2025-12-26 | $69053936637.35           | $69553936637.35            | 98.5200%                  | 99.2300%                   |
| 2025-12-29 | $70445551569.11           | $70945551569.11            | 98.5500%                  | 99.2500%                   |
| 2025-12-30 | $68759847744.94           | $69259847744.94            | 98.5200%                  | 99.2300%                   |
| 2025-12-31 | $70661913932.77           | $70661913932.77            | 99.2600%                  | 99.2600%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2025-12-01 | 4.0400%             |
| 2025-12-02 | 4.0400%             |
| 2025-12-03 | 4.0300%             |
| 2025-12-04 | 4.0200%             |
| 2025-12-05 | 3.9800%             |
| 2025-12-08 | 3.9800%             |
| 2025-12-09 | 3.9700%             |
| 2025-12-10 | 3.9700%             |
| 2025-12-11 | 3.9500%             |
| 2025-12-12 | 3.8900%             |
| 2025-12-15 | 3.8800%             |
| 2025-12-16 | 3.8500%             |
| 2025-12-17 | 3.8400%             |
| 2025-12-18 | 3.8300%             |
| 2025-12-19 | 3.8200%             |
| 2025-12-22 | 3.8200%             |
| 2025-12-23 | 3.8200%             |
| 2025-12-24 | 3.8100%             |
| 2025-12-26 | 3.8300%             |
| 2025-12-29 | 3.8300%             |
| 2025-12-30 | 3.8300%             |
| 2025-12-31 | 3.8500%             |

### Daily Net Asset Value per Share (Series)
| Date       | Net Asset Value per Share   |
|:---|:---|
| 2025-12-01 | 1.0001                      |
|  |  |
| 2025-12-02 | 1.0001                      |
|  |  |
| 2025-12-03 | 1.0002                      |
|  |  |
| 2025-12-04 | 1.0002                      |
|  |  |
| 2025-12-05 | 1.0002                      |
|  |  |
| 2025-12-08 | 1.0002                      |
|  |  |
| 2025-12-09 | 1.0001                      |
|  |  |
| 2025-12-10 | 1.0002                      |
|  |  |
| 2025-12-11 | 1.0002                      |
|  |  |
| 2025-12-12 | 1.0002                      |
|  |  |
| 2025-12-15 | 1.0002                      |
|  |  |
| 2025-12-16 | 1.0003                      |
|  |  |
| 2025-12-17 | 1.0003                      |
|  |  |
| 2025-12-18 | 1.0003                      |
|  |  |
| 2025-12-19 | 1.0002                      |
|  |  |
| 2025-12-22 | 1.0002                      |
|  |  |
| 2025-12-23 | 1.0002                      |
|  |  |
| 2025-12-24 | 1.0002                      |
|  |  |
| 2025-12-26 | 1.0002                      |
|  |  |
| 2025-12-29 | 1.0002                      |
|  |  |
| 2025-12-30 | 1.0002                      |
|  |  |
| 2025-12-31 | 1.0002                      |
|  |  |

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

### Class: A

- **Minimum Initial Investment:** $1000000000.00

- **Net Assets of Class:** $6357077484.37

- **Number of Shares Outstanding:** 6357150644.5700

- **Expense Reimbursement/Waiver:** 174948.00

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2025-12-01 | 1.0001          |
|  |  |
| 2025-12-02 | 1.0001          |
|  |  |
| 2025-12-03 | 1.0002          |
|  |  |
| 2025-12-04 | 1.0002          |
|  |  |
| 2025-12-05 | 1.0002          |
|  |  |
| 2025-12-08 | 1.0002          |
|  |  |
| 2025-12-09 | 1.0001          |
|  |  |
| 2025-12-10 | 1.0002          |
|  |  |
| 2025-12-11 | 1.0002          |
|  |  |
| 2025-12-12 | 1.0002          |
|  |  |
| 2025-12-15 | 1.0002          |
|  |  |
| 2025-12-16 | 1.0003          |
|  |  |
| 2025-12-17 | 1.0003          |
|  |  |
| 2025-12-18 | 1.0003          |
|  |  |
| 2025-12-19 | 1.0002          |
|  |  |
| 2025-12-22 | 1.0002          |
|  |  |
| 2025-12-23 | 1.0002          |
|  |  |
| 2025-12-24 | 1.0002          |
|  |  |
| 2025-12-26 | 1.0002          |
|  |  |
| 2025-12-29 | 1.0002          |
|  |  |
| 2025-12-30 | 1.0002          |
|  |  |
| 2025-12-31 | 1.0002          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2025-12-01 | $32422349.64              | $16209295.33            |
| 2025-12-02 | $14.01                    | $0.01                   |
| 2025-12-03 | $0.00                     | $3296.13                |
| 2025-12-04 | $0.00                     | $0.00                   |
| 2025-12-05 | $0.00                     | $0.00                   |
| 2025-12-08 | $1467358223.00            | $240139.00              |
| 2025-12-09 | $0.00                     | $18024254.00            |
| 2025-12-10 | $0.00                     | $0.00                   |
| 2025-12-11 | $1128621251.00            | $147963383.00           |
| 2025-12-12 | $0.00                     | $13402396.00            |
| 2025-12-15 | $0.00                     | $0.00                   |
| 2025-12-16 | $0.00                     | $21102172.00            |
| 2025-12-17 | $0.00                     | $4393658.00             |
| 2025-12-18 | $0.00                     | $1604958674.61          |
| 2025-12-19 | $0.00                     | $0.00                   |
| 2025-12-22 | $0.00                     | $0.00                   |
| 2025-12-23 | $0.00                     | $0.00                   |
| 2025-12-24 | $0.00                     | $0.00                   |
| 2025-12-26 | $0.00                     | $0.00                   |
| 2025-12-29 | $1324000000.00            | $1054861186.10          |
| 2025-12-30 | $0.00                     | $175000000.00           |
| 2025-12-31 | $0.00                     | $0.00                   |

**Total Gross Subscriptions (Month):** $3952401837.65

**Total Gross Redemptions (Month):** $3056158454.18

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2025-12-01 | 3.9600%           |
| 2025-12-02 | 3.9600%           |
| 2025-12-03 | 3.9500%           |
| 2025-12-04 | 3.9400%           |
| 2025-12-05 | 3.9000%           |
| 2025-12-08 | 3.9000%           |
| 2025-12-09 | 3.8900%           |
| 2025-12-10 | 3.8900%           |
| 2025-12-11 | 3.8700%           |
| 2025-12-12 | 3.8100%           |
| 2025-12-15 | 3.8000%           |
| 2025-12-16 | 3.7700%           |
| 2025-12-17 | 3.7600%           |
| 2025-12-18 | 3.7500%           |
| 2025-12-19 | 3.7400%           |
| 2025-12-22 | 3.7400%           |
| 2025-12-23 | 3.7400%           |
| 2025-12-24 | 3.7300%           |
| 2025-12-26 | 3.7500%           |
| 2025-12-29 | 3.7500%           |
| 2025-12-30 | 3.7500%           |
| 2025-12-31 | 3.7700%           |

**Beneficial/Record Owner Categories**
| Category                  | Other Category   | Record Owner %   | Beneficial Owner %   |
|:---|:---|:---|:---|
| Non-financial corporation |  | 99.9900%         | 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: FSSgAK183, C.3 - LEI: N/A, C.5 - Other ID: FSSgAK183
- **C.18 - Value (incl. sponsor support):** $6379070270.84
- **C.18.a - Value (excl. sponsor support):** $6379070270.84
- **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