# EDGAR Filing Document

**Accession Number:** 0001107414
**File Stem:** 0001410368-26-042649
**Filing Date:** 2026-5
**Character Count:** 13853
**Document Hash:** 1879e8a1c170b49eaf3f196e0f27c944
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001410368-26-042649.hdr.sgml**: 20260507

**ACCESSION NUMBER**: 0001410368-26-042649

**CONFORMED SUBMISSION TYPE**: N-MFP3

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20260430

**FILED AS OF DATE**: 20260507

**DATE AS OF CHANGE**: 20260507

**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:** 26951462

**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):** 2026-04-30

**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:** $4052900046.67

- **Amortized Cost of Portfolio Securities:** $4052900046.67

- **Cash:** $0.00

- **Total Other Assets:** $0.00

- **Total Liabilities:** $11944001.34

- **Net Assets of Series:** $4040956045.33

- **Number of Shares Outstanding (Series):** 4041030792.0200

- **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 (%)   |
|:---|:---|:---|:---|:---|
| 2026-04-01 | $69553118187.14           | $69553118187.14            | 98.4800%                  | 98.4800%                   |
| 2026-04-02 | $68724878336.41           | $69199878336.41            | 97.3800%                  | 98.0600%                   |
| 2026-04-03 | $0.00                     | $0.00                      | 0.0000%                   | 0.0000%                    |
| 2026-04-06 | $71612758106.90           | $72087758106.90            | 97.5000%                  | 98.1400%                   |
| 2026-04-07 | $70314737884.44           | $70789737884.44            | 97.4500%                  | 98.1100%                   |
| 2026-04-08 | $69472230503.17           | $69697230503.17            | 97.7600%                  | 98.0800%                   |
| 2026-04-09 | $67799462516.03           | $68049462516.03            | 97.6700%                  | 98.0300%                   |
| 2026-04-10 | $69055034337.01           | $69305034337.01            | 97.3800%                  | 97.7300%                   |
| 2026-04-13 | $71039624181.54           | $71569624181.54            | 97.4600%                  | 98.1900%                   |
| 2026-04-14 | $70453091647.63           | $70703091647.63            | 97.4400%                  | 97.7900%                   |
| 2026-04-15 | $71933556221.34           | $71933556221.34            | 97.8300%                  | 97.8300%                   |
| 2026-04-16 | $71651936769.15           | $71901936769.15            | 97.4800%                  | 97.8200%                   |
| 2026-04-17 | $70127017820.47           | $70377017820.47            | 97.4100%                  | 97.7600%                   |
| 2026-04-20 | $72466915703.60           | $72826915703.60            | 97.5000%                  | 97.9800%                   |
| 2026-04-21 | $72955388391.93           | $73315388391.93            | 97.5100%                  | 97.9900%                   |
| 2026-04-22 | $72257865279.85           | $72367865279.85            | 97.8200%                  | 97.9700%                   |
| 2026-04-23 | $68466415490.15           | $68576415490.15            | 97.7000%                  | 97.8500%                   |
| 2026-04-24 | $67591843311.04           | $67591843311.04            | 97.8100%                  | 97.8100%                   |
| 2026-04-27 | $68187940181.78           | $68187940181.78            | 97.8300%                  | 97.8300%                   |
| 2026-04-28 | $71237765638.86           | $71237765638.86            | 97.9200%                  | 97.9200%                   |
| 2026-04-29 | $73616300231.04           | $73616300231.04            | 97.9800%                  | 97.9800%                   |
| 2026-04-30 | $75221047027.56           | $75221047027.56            | 98.1700%                  | 98.1700%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2026-04-01 | 3.7100%             |
| 2026-04-02 | 3.7100%             |
| 2026-04-03 | 0.0000%             |
| 2026-04-06 | 3.7100%             |
| 2026-04-07 | 3.7000%             |
| 2026-04-08 | 3.7000%             |
| 2026-04-09 | 3.7000%             |
| 2026-04-10 | 3.6900%             |
| 2026-04-13 | 3.6900%             |
| 2026-04-14 | 3.6900%             |
| 2026-04-15 | 3.7000%             |
| 2026-04-16 | 3.7000%             |
| 2026-04-17 | 3.7100%             |
| 2026-04-20 | 3.7100%             |
| 2026-04-21 | 3.7100%             |
| 2026-04-22 | 3.7000%             |
| 2026-04-23 | 3.7000%             |
| 2026-04-24 | 3.7100%             |
| 2026-04-27 | 3.7100%             |
| 2026-04-28 | 3.7100%             |
| 2026-04-29 | 3.7100%             |
| 2026-04-30 | 3.7100%             |

### Daily Net Asset Value per Share (Series)
| Date       | Net Asset Value per Share   |
|:---|:---|
| 2026-04-01 | 0.9999                      |
|  |  |
| 2026-04-02 | 0.9999                      |
|  |  |
| 2026-04-03 | 0.0000                      |
|  |  |
| 2026-04-06 | 0.9999                      |
|  |  |
| 2026-04-07 | 0.9999                      |
|  |  |
| 2026-04-08 | 0.9999                      |
|  |  |
| 2026-04-09 | 0.9999                      |
|  |  |
| 2026-04-10 | 0.9999                      |
|  |  |
| 2026-04-13 | 0.9999                      |
|  |  |
| 2026-04-14 | 0.9999                      |
|  |  |
| 2026-04-15 | 0.9999                      |
|  |  |
| 2026-04-16 | 0.9999                      |
|  |  |
| 2026-04-17 | 1.0000                      |
|  |  |
| 2026-04-20 | 1.0000                      |
|  |  |
| 2026-04-21 | 0.9999                      |
|  |  |
| 2026-04-22 | 1.0000                      |
|  |  |
| 2026-04-23 | 0.9999                      |
|  |  |
| 2026-04-24 | 1.0000                      |
|  |  |
| 2026-04-27 | 0.9999                      |
|  |  |
| 2026-04-28 | 0.9999                      |
|  |  |
| 2026-04-29 | 0.9999                      |
|  |  |
| 2026-04-30 | 1.0000                      |
|  |  |

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

### Class: A

- **Minimum Initial Investment:** $1000000000.00

- **Net Assets of Class:** $4040956045.33

- **Number of Shares Outstanding:** 4041030792.0200

- **Expense Reimbursement/Waiver:** 112114.00

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2026-04-01 | 0.9999          |
|  |  |
| 2026-04-02 | 0.9999          |
|  |  |
| 2026-04-03 | 0.0000          |
|  |  |
| 2026-04-06 | 0.9999          |
|  |  |
| 2026-04-07 | 0.9999          |
|  |  |
| 2026-04-08 | 0.9999          |
|  |  |
| 2026-04-09 | 0.9999          |
|  |  |
| 2026-04-10 | 0.9999          |
|  |  |
| 2026-04-13 | 0.9999          |
|  |  |
| 2026-04-14 | 0.9999          |
|  |  |
| 2026-04-15 | 0.9999          |
|  |  |
| 2026-04-16 | 0.9999          |
|  |  |
| 2026-04-17 | 1.0000          |
|  |  |
| 2026-04-20 | 1.0000          |
|  |  |
| 2026-04-21 | 0.9999          |
|  |  |
| 2026-04-22 | 1.0000          |
|  |  |
| 2026-04-23 | 0.9999          |
|  |  |
| 2026-04-24 | 1.0000          |
|  |  |
| 2026-04-27 | 0.9999          |
|  |  |
| 2026-04-28 | 0.9999          |
|  |  |
| 2026-04-29 | 0.9999          |
|  |  |
| 2026-04-30 | 1.0000          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2026-04-01 | $59824764.62              | $8999672.53             |
| 2026-04-02 | $1.90                     | $51112635.09            |
| 2026-04-03 | $0.00                     | $0.00                   |
| 2026-04-06 | $436607.34                | $0.00                   |
| 2026-04-07 | $0.00                     | $1243400000.00          |
| 2026-04-08 | $5000000.00               | $16573308.00            |
| 2026-04-09 | $0.00                     | $332737.00              |
| 2026-04-10 | $0.00                     | $5605587.00             |
| 2026-04-13 | $841985441.00             | $113217618.00           |
| 2026-04-14 | $0.00                     | $0.00                   |
| 2026-04-15 | $0.00                     | $56979989.00            |
| 2026-04-16 | $0.00                     | $0.00                   |
| 2026-04-17 | $5100000.00               | $0.00                   |
| 2026-04-20 | $0.00                     | $39305458.00            |
| 2026-04-21 | $1977888189.12            | $313146524.00           |
| 2026-04-22 | $0.00                     | $70967676.00            |
| 2026-04-23 | $0.00                     | $398260356.00           |
| 2026-04-24 | $0.00                     | $0.00                   |
| 2026-04-27 | $0.00                     | $0.00                   |
| 2026-04-28 | $4.00                     | $267645502.00           |
| 2026-04-29 | $282909712.00             | $773404004.00           |
| 2026-04-30 | $0.00                     | $2.00                   |

**Total Gross Subscriptions (Month):** $3173144719.98

**Total Gross Redemptions (Month):** $3358951068.62

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2026-04-01 | 3.6300%           |
| 2026-04-02 | 3.6300%           |
| 2026-04-03 | 0.0000%           |
| 2026-04-06 | 3.6300%           |
| 2026-04-07 | 3.6200%           |
| 2026-04-08 | 3.6200%           |
| 2026-04-09 | 3.6200%           |
| 2026-04-10 | 3.6100%           |
| 2026-04-13 | 3.6100%           |
| 2026-04-14 | 3.6100%           |
| 2026-04-15 | 3.6200%           |
| 2026-04-16 | 3.6200%           |
| 2026-04-17 | 3.6300%           |
| 2026-04-20 | 3.6300%           |
| 2026-04-21 | 3.6300%           |
| 2026-04-22 | 3.6200%           |
| 2026-04-23 | 3.6200%           |
| 2026-04-24 | 3.6300%           |
| 2026-04-27 | 3.6300%           |
| 2026-04-28 | 3.6300%           |
| 2026-04-29 | 3.6300%           |
| 2026-04-30 | 3.6300%           |

**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: 5493008OWE0VKOXO4934, C.5 - Other ID: FSSgAK183
- **C.18 - Value (incl. sponsor support):** $4052900046.67
- **C.18.a - Value (excl. sponsor support):** $4052900046.67
- **C.19 - Percentage of Net Assets:** 100.0000%
- **C.17 - Yield as of Reporting Date:** 0.0000%
- **C.11 - Maturity Date (WAM):** 2026-05-01
- **C.12 - Maturity Date (WAL):** 2026-05-01
- **C.13 - Final Legal Maturity Date:** 2026-05-01
- **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:** 2026-05-07

**By:** /s/ Chad Hallett

**Name of Signing Officer:** Chad Hallett

**Title of Signing Officer:** Deputy Treasurer