Report of Independent Registered Public
Accounting Firm

To the Board of Trustees of Vanguard
Institutional Index Funds and Shareholders of
Vanguard Institutional Index Fund and
Vanguard Institutional Total Stock Market Index
Fund

In planning and performing our audits of the
financial statements of Vanguard Institutional
Index Fund and Vanguard Institutional Total
Stock Market Index Fund (constituting Vanguard
Institutional Index Funds, hereafter collectively
referred to as the "Funds") as of and for the year
ended December 31, 2022, in accordance with
the standards of the Public Company
Accounting Oversight Board (United States)
(PCAOB), we considered the Funds' internal
control over financial reporting, including
controls over safeguarding securities, as a basis
for designing our auditing procedures for the
purpose of expressing our opinion on the
financial statements and to comply with the
requirements of Form N-CEN, but not for the
purpose of expressing an opinion on the
effectiveness of the Funds' internal control over
financial reporting. Accordingly, we do not
express an opinion on the effectiveness of the
Funds' internal control over financial reporting.

The management of the Funds is responsible for
establishing and maintaining effective internal
control over financial reporting. In fulfilling this
responsibility, estimates and judgments by
management are required to assess the
expected benefits and related costs of controls.
A company's internal control over financial
reporting is a process designed to provide
reasonable assurance regarding the reliability of
financial reporting and the preparation of
financial statements for external purposes in
accordance with generally accepted accounting
principles. A company's internal control over
financial reporting includes those policies and
procedures that (1) pertain to the maintenance
of records that, in reasonable detail, accurately
and fairly reflect the transactions and
dispositions of the assets of the company; (2)
provide reasonable assurance that transactions
are recorded as necessary to permit preparation
of financial statements in accordance with
generally accepted accounting principles, and
that receipts and expenditures of the company
are being made only in accordance with
authorizations of management and directors of
the company; and (3) provide reasonable
assurance regarding prevention or timely
detection of unauthorized acquisition, use or
disposition of a company's assets that could
have a material effect on the financial
statements.

Because of its inherent limitations, internal
control over financial reporting may not prevent
or detect misstatements. Also, projections of any
evaluation of effectiveness to future periods are
subject to the risk that controls may become
inadequate because of changes in conditions, or
that the degree of compliance with the policies
or procedures may deteriorate.

A deficiency in internal control over financial
reporting exists when the design or operation of
a control does not allow management or
employees, in the normal course of performing
their assigned functions, to prevent or detect
misstatements on a timely basis. A material
weakness is a deficiency, or a combination of
deficiencies, in internal control over financial
reporting, such that there is a reasonable
possibility that a material misstatement of the
company's annual or interim financial statements
will not be prevented or detected on a timely
basis.

Our consideration of the Funds' internal control
over financial reporting was for the limited
purpose described in the first paragraph and
would not necessarily disclose all deficiencies in
internal control over financial reporting that
might be material weaknesses under standards
established by the PCAOB. However, we noted
no deficiencies in the Funds' internal control
over financial reporting and its operation,
including controls over safeguarding securities,
that we consider to be a material weakness as
defined above as of December 31, 2022.

This report is intended solely for the information
and use of the Board of Trustees of Vanguard
Institutional Index Funds and the Securities and
Exchange Commission and is not intended to be
and should not be used by anyone other than
these specified parties.



/s/ PricewaterhouseCoopers LLP
Philadelphia, Pennsylvania
February 15, 2023