# EDGAR Filing Document

**Accession Number:** 0001107414
**File Stem:** 0001410368-26-057218
**Filing Date:** 2026-6
**Character Count:** 13123
**Document Hash:** 18a5da0abc50a5afa6151610e9134e3e
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001410368-26-057218.hdr.sgml**: 20260605

**ACCESSION NUMBER**: 0001410368-26-057218

**CONFORMED SUBMISSION TYPE**: N-MFP3

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20260531

**FILED AS OF DATE**: 20260605

**DATE AS OF CHANGE**: 20260605

**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:** 261067180

**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):** 2026-05-31

**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:** $3617374318.72

- **Amortized Cost of Portfolio Securities:** $3617374318.72

- **Cash:** $0.00

- **Total Other Assets:** $0.00

- **Total Liabilities:** $11924955.36

- **Net Assets of Series:** $3605449363.36

- **Number of Shares Outstanding (Series):** 3605524110.0500

- **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 (%)   |
|:---|:---|:---|:---|:---|
| 2026-05-01 | $76520796776.95           | $76620796776.95            | 98.1800%                  | 98.3100%                   |
| 2026-05-04 | $85233519081.72           | $85558519081.72            | 98.1200%                  | 98.5000%                   |
| 2026-05-05 | $86325564791.72           | $86650564791.72            | 98.1400%                  | 98.5100%                   |
| 2026-05-06 | $85201077499.43           | $85526077499.43            | 98.1200%                  | 98.4900%                   |
| 2026-05-07 | $72955915411.32           | $73760915411.32            | 97.5500%                  | 98.6300%                   |
| 2026-05-08 | $70183573450.39           | $70183573450.39            | 98.1500%                  | 98.1500%                   |
| 2026-05-11 | $71299733624.69           | $71299733624.69            | 97.8800%                  | 97.8800%                   |
| 2026-05-12 | $74015248114.77           | $74015248114.77            | 97.9600%                  | 97.9600%                   |
| 2026-05-13 | $71761379084.78           | $71761379084.78            | 97.9000%                  | 97.9000%                   |
| 2026-05-14 | $70591911977.69           | $70591911977.69            | 97.8600%                  | 97.8600%                   |
| 2026-05-15 | $70424992496.50           | $70424992496.50            | 97.8400%                  | 97.8400%                   |
| 2026-05-18 | $72334842526.88           | $72334842526.88            | 97.9000%                  | 97.9000%                   |
| 2026-05-19 | $72465368351.47           | $72465368351.47            | 97.9100%                  | 97.9100%                   |
| 2026-05-20 | $72269887039.35           | $72269887039.35            | 97.9000%                  | 97.9000%                   |
| 2026-05-21 | $71265356192.85           | $71265356192.85            | 97.8700%                  | 97.8700%                   |
| 2026-05-22 | $70028798614.57           | $70028798614.57            | 97.8000%                  | 97.8000%                   |
| 2026-05-26 | $70668486174.03           | $70668486174.03            | 97.8400%                  | 97.8400%                   |
| 2026-05-27 | $73762757121.93           | $73762757121.93            | 97.9200%                  | 97.9200%                   |
| 2026-05-28 | $73301847911.75           | $73301847911.75            | 97.9000%                  | 97.9000%                   |
| 2026-05-29 | $76773156744.97           | $76773156744.97            | 97.9800%                  | 97.9800%                   |

### 7-Day Gross Yield
| Date       | 7-Day Gross Yield   |
|:---|:---|
| 2026-05-01 | 3.7000%             |
| 2026-05-04 | 3.6900%             |
| 2026-05-05 | 3.6900%             |
| 2026-05-06 | 3.6900%             |
| 2026-05-07 | 3.6800%             |
| 2026-05-08 | 3.6800%             |
| 2026-05-11 | 3.6700%             |
| 2026-05-12 | 3.6700%             |
| 2026-05-13 | 3.6700%             |
| 2026-05-14 | 3.6700%             |
| 2026-05-15 | 3.6600%             |
| 2026-05-18 | 3.6600%             |
| 2026-05-19 | 3.6600%             |
| 2026-05-20 | 3.6500%             |
| 2026-05-21 | 3.6500%             |
| 2026-05-22 | 3.6400%             |
| 2026-05-26 | 3.6500%             |
| 2026-05-27 | 3.6600%             |
| 2026-05-28 | 3.6700%             |
| 2026-05-29 | 3.6800%             |

### Daily Net Asset Value per Share (Series)
| Date       | Net Asset Value per Share   |
|:---|:---|
| 2026-05-01 | 1.0000                      |
|  |  |
| 2026-05-04 | 1.0000                      |
|  |  |
| 2026-05-05 | 1.0000                      |
|  |  |
| 2026-05-06 | 1.0000                      |
|  |  |
| 2026-05-07 | 1.0000                      |
|  |  |
| 2026-05-08 | 1.0000                      |
|  |  |
| 2026-05-11 | 0.9999                      |
|  |  |
| 2026-05-12 | 1.0000                      |
|  |  |
| 2026-05-13 | 1.0000                      |
|  |  |
| 2026-05-14 | 0.9999                      |
|  |  |
| 2026-05-15 | 0.9999                      |
|  |  |
| 2026-05-18 | 1.0000                      |
|  |  |
| 2026-05-19 | 1.0000                      |
|  |  |
| 2026-05-20 | 1.0000                      |
|  |  |
| 2026-05-21 | 0.9999                      |
|  |  |
| 2026-05-22 | 0.9999                      |
|  |  |
| 2026-05-26 | 0.9999                      |
|  |  |
| 2026-05-27 | 0.9999                      |
|  |  |
| 2026-05-28 | 0.9999                      |
|  |  |
| 2026-05-29 | 0.9999                      |
|  |  |

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

### Class: A

- **Minimum Initial Investment:** $1000000000.00

- **Net Assets of Class:** $3605449363.36

- **Number of Shares Outstanding:** 3605524110.0500

- **Expense Reimbursement/Waiver:** 113243.00

**Daily Net Asset Value per Share (Class)**
| Date       | NAV per Share   |
|:---|:---|
| 2026-05-01 | 1.0000          |
|  |  |
| 2026-05-04 | 1.0000          |
|  |  |
| 2026-05-05 | 1.0000          |
|  |  |
| 2026-05-06 | 1.0000          |
|  |  |
| 2026-05-07 | 1.0000          |
|  |  |
| 2026-05-08 | 1.0000          |
|  |  |
| 2026-05-11 | 0.9999          |
|  |  |
| 2026-05-12 | 1.0000          |
|  |  |
| 2026-05-13 | 1.0000          |
|  |  |
| 2026-05-14 | 0.9999          |
|  |  |
| 2026-05-15 | 0.9999          |
|  |  |
| 2026-05-18 | 1.0000          |
|  |  |
| 2026-05-19 | 1.0000          |
|  |  |
| 2026-05-20 | 1.0000          |
|  |  |
| 2026-05-21 | 0.9999          |
|  |  |
| 2026-05-22 | 0.9999          |
|  |  |
| 2026-05-26 | 0.9999          |
|  |  |
| 2026-05-27 | 0.9999          |
|  |  |
| 2026-05-28 | 0.9999          |
|  |  |
| 2026-05-29 | 0.9999          |
|  |  |

**Daily Shareholder Flows**
| Date       | Gross Subscriptions ($)   | Gross Redemptions ($)   |
|:---|:---|:---|
| 2026-05-01 | $22457028.89              | $62983848.36            |
| 2026-05-04 | $12.92                    | $0.00                   |
| 2026-05-05 | $0.00                     | $70594018.23            |
| 2026-05-06 | $0.00                     | $707942.00              |
| 2026-05-07 | $0.00                     | $0.00                   |
| 2026-05-08 | $0.00                     | $0.00                   |
| 2026-05-11 | $0.00                     | $0.00                   |
| 2026-05-12 | $0.00                     | $526590.00              |
| 2026-05-13 | $0.00                     | $0.00                   |
| 2026-05-14 | $0.00                     | $0.00                   |
| 2026-05-15 | $0.00                     | $0.00                   |
| 2026-05-18 | $0.00                     | $0.00                   |
| 2026-05-19 | $0.00                     | $0.00                   |
| 2026-05-20 | $0.00                     | $0.00                   |
| 2026-05-21 | $0.00                     | $0.00                   |
| 2026-05-22 | $0.00                     | $100000000.00           |
| 2026-05-26 | $0.00                     | $5759054.19             |
| 2026-05-27 | $0.00                     | $0.00                   |
| 2026-05-28 | $0.00                     | $149392271.00           |
| 2026-05-29 | $0.00                     | $68000000.00            |

**Total Gross Subscriptions (Month):** $22457041.81

**Total Gross Redemptions (Month):** $457963723.78

**7-Day Net Yield (Class)**
| Date       | 7-Day Net Yield   |
|:---|:---|
| 2026-05-01 | 3.6200%           |
| 2026-05-04 | 3.6100%           |
| 2026-05-05 | 3.6100%           |
| 2026-05-06 | 3.6100%           |
| 2026-05-07 | 3.6000%           |
| 2026-05-08 | 3.6000%           |
| 2026-05-11 | 3.5900%           |
| 2026-05-12 | 3.5900%           |
| 2026-05-13 | 3.5900%           |
| 2026-05-14 | 3.5900%           |
| 2026-05-15 | 3.5800%           |
| 2026-05-18 | 3.5800%           |
| 2026-05-19 | 3.5800%           |
| 2026-05-20 | 3.5700%           |
| 2026-05-21 | 3.5700%           |
| 2026-05-22 | 3.5600%           |
| 2026-05-26 | 3.5700%           |
| 2026-05-27 | 3.5800%           |
| 2026-05-28 | 3.5900%           |
| 2026-05-29 | 3.6000%           |

**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):** $3617374318.72
- **C.18.a - Value (excl. sponsor support):** $3617374318.72
- **C.19 - Percentage of Net Assets:** 100.0000%
- **C.17 - Yield as of Reporting Date:** 0.0000%
- **C.11 - Maturity Date (WAM):** 2026-06-01
- **C.12 - Maturity Date (WAL):** 2026-06-01
- **C.13 - Final Legal Maturity Date:** 2026-06-01
- **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:** 2026-06-05

**By:** /s/ Chad Hallett

**Name of Signing Officer:** Chad Hallett

**Title of Signing Officer:** Deputy Treasurer