# EDGAR Filing Document

**Accession Number:** 0000862084
**File Stem:** 0000862084-26-000023
**Filing Date:** 2026-2
**Character Count:** 14912
**Document Hash:** 5ed0c930e75109a36613e06fab8a165b
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000862084-26-000023.hdr.sgml**: 20260226

**ACCESSION NUMBER**: 0000862084-26-000023

**CONFORMED SUBMISSION TYPE**: NPORT-P

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20251231

**FILED AS OF DATE**: 20260226

**DATE AS OF CHANGE**: 20260226

**PERIOD START**: 20251231

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** VANGUARD INSTITUTIONAL INDEX FUNDS
- **CENTRAL INDEX KEY:** 0000862084

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** NPORT-P
- **SEC ACT:** 1940 Act
- **SEC FILE NUMBER:** 811-06093
- **FILM NUMBER:** 26688278

**BUSINESS ADDRESS:**
- **STREET 1:** PO BOX 2600
- **STREET 2:** V26
- **CITY:** VALLEY FORGE
- **STATE:** PA
- **ZIP:** 19482
- **BUSINESS PHONE:** 6106691000

**MAIL ADDRESS:**
- **STREET 1:** PO BOX 2600
- **STREET 2:** V26
- **CITY:** VALLEY FORGE
- **STATE:** PA
- **ZIP:** 19482

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** VANGUARD INSTITUTIONAL INDEX FUND
- **DATE OF NAME CHANGE:** 19920703

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** VANGUARD INSTITUTIONAL EQUITY INDEX FUND INC
- **DATE OF NAME CHANGE:** 19900701

## Series and Classes Contracts Data

### Vanguard 0-3 Month Treasury Bill ETF (Series ID: S000090172)

| Class ID   | Class Name   | Ticker Symbol   |
|:---|:---|:---|
| C000257083 | ETF Shares   | VBIL            |

## Form NPORT-P: Monthly Portfolio Investments Report

### NPORT-P: Part A: General Information

**Item A.1. Information about the Registrant.**

- **a. Name of Registrant:** VANGUARD INSTITUTIONAL INDEX FUNDS

- **b. Investment Company Act file number:** 811-06093

- **c. CIK number of Registrant:** 0000862084

- **d. LEI of Registrant:** 549300HU31ENFT74XN04

- **e. Address and telephone number of Registrant.**

  - **Street Address 1:** 100 Vanguard Boulevard

  - **City:** Malvern

  - **State:** PA

  - **Foreign country:** US

  - **Zip / Postal Code:** 19355

  - **Telephone number:** 610-669-1000

**Item A.2. Information about the Series.**

- **a. Name of Series:** VANGUARD 0-3 MONTH TREASURY BILL ETF

- **b. EDGAR series identifier (if any):** S000090172

- **c. LEI of Series:** 52990070DGBTWFWX8S21

**Item A.3. Reporting period.**

- **a. Date of fiscal year-end:** 2025-12-31

- **b. Date as of which information is reported:** 2025-12-31

**Item A.4. Final filing**

Does the Fund anticipate that this will be its final filing on Form N-PORT? **No**

### Fund Information

**Total Assets:** $4638422624.81

**Total Liabilities:** $138924.12

**Net Assets:** $4638283700.69

**Cash Not Reported:** $1797209.86

**Currency Risk Metrics (dv01):**

- 

**Credit Spread Risk - Investment Grade (dv01):**

- **3-Month:** 0.00000000 | **1-Year:** 0.00000000 | **5-Year:** 0.00000000 | **10-Year:** 0.00000000 | **30-Year:** 0.00000000

**Credit Spread Risk - Non-Investment Grade (dv01):**

- **3-Month:** 0.00000000 | **1-Year:** 0.00000000 | **5-Year:** 0.00000000 | **10-Year:** 0.00000000 | **30-Year:** 0.00000000

**Monthly Return Information**

| Class               | Month 1 Return (%)   | Month 2 Return (%)   | Month 3 Return (%)   |
|:---|:---|:---|:---|
| Class ID C000257083 | 0.36%                | 0.29%                | 0.35%                |

**Monthly Gains & Losses**

| Period   | Net Realized Gain/Loss   | Net Unrealized Appreciation/Depreciation   |
|:---|:---|:---|
| Month 1  | $760.69                  | $768366.37                                 |
| Month 2  | $-23629.60               | $-41161.53                                 |
| Month 3  | $1171.69                 | $-60678.34                                 |

### Schedule of Portfolio Investments

| Name                                              | Title                          | Identifiers                                   | Payoff Profile   | Asset Category   | Issuer Category   | Country   |   Balance | Units   | Value (USD)   | % of Net Assets   | Maturity Date   | Coupon Type   | Annualized Rate (%)   | Restricted?   |   Fair Value Level | Lending Status   |
|:---|:---|:---|:---|:---|:---|:---|---:|:---|:---|:---|:---|:---|:---|:---|---:|:---|
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797SB4<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 155038000 | PA      | $153984581.92 | 3.32%             | 2026-03-12      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797SC2<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 159051000 | PA      | $157760212.08 | 3.40%             | 2026-03-26      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797SY4<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        |  69029000 | PA      | $68583849.24  | 1.48%             | 2026-03-10      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797RV1<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 158525000 | PA      | $157557160.47 | 3.40%             | 2026-03-05      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797RK5<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 234081000 | PA      | $233459515.07 | 5.03%             | 2026-01-29      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797RT6<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 159050000 | PA      | $158399706.55 | 3.42%             | 2026-02-12      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797TA5<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        |  69026000 | PA      | $68478537.57  | 1.48%             | 2026-03-24      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797RH2<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 239601000 | PA      | $239461032.32 | 5.16%             | 2026-01-08      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797PM3<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 207080000 | PA      | $206097059.62 | 4.44%             | 2026-02-19      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797RU3<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 159052000 | PA      | $158178429.17 | 3.41%             | 2026-02-26      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797SE8<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 246926000 | PA      | $246830521.20 | 5.32%             | 2026-01-06      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797SH1<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 234374000 | PA      | $233797015.72 | 5.04%             | 2026-01-27      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797RL3<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 234100000 | PA      | $233314009.32 | 5.03%             | 2026-02-05      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797SG3<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 247104000 | PA      | $246664772.76 | 5.32%             | 2026-01-20      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797RJ8<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 229365000 | PA      | $229070137.62 | 4.94%             | 2026-01-15      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797PV3<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 207063000 | PA      | $205519920.97 | 4.43%             | 2026-03-19      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| Vanguard Cmt Funds-Vanguard Market Liquidity Fund | Vanguard Market Liquidity Fund | CUSIP: N/A<br>LEI: 1I6HV0TLSTR3A4XQ6L78       | Long             | STIV             | CORP              | US        |   7255824 | NS      | $7255823.60   | 0.16%             |  |  |  | No            |                  1 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797SF5<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 247620000 | PA      | $247352914.59 | 5.33%             | 2026-01-13      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797SD0<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        |  72361000 | PA      | $71717891.62  | 1.55%             | 2026-04-02      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797SQ1<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 149026000 | PA      | $148453677.57 | 3.20%             | 2026-02-10      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797SS7<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 149052000 | PA      | $148275190.18 | 3.20%             | 2026-02-24      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797SZ1<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        |  67789000 | PA      | $67301296.11  | 1.45%             | 2026-03-17      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797RA7<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 242334000 | PA      | $242310876.55 | 5.22%             | 2026-01-02      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797SR9<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 149026000 | PA      | $148351906.19 | 3.20%             | 2026-02-17      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797SJ7<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 146708000 | PA      | $146246358.38 | 3.15%             | 2026-02-03      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797TB3<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        |  68405000 | PA      | $67817249.19  | 1.46%             | 2026-03-31      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797PD3<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        | 276332000 | PA      | $275782406.09 | 5.95%             | 2026-01-22      | None          | 0.00%                 | No            |                  2 | On Loan: No      |
| United States Treasury Bill                       | TREASURY BILL                  | CUSIP: 912797ST5<br>LEI: 254900HROIFWPRGM1V77 | Long             | DBT              | UST               | US        |  68855000 | PA      | $68446460.56  | 1.48%             | 2026-03-03      | None          | 0.00%                 | No            |                  2 | On Loan: No      |

### Signature

**Date Signed:** 2026-02-26

**Name of Applicant:** VANGUARD INSTITUTIONAL INDEX FUNDS

**Signature:** Ashley Grim

**Name of Signer:** Ashley Grim

**Title:** Treasurer