INTERNAL CONTROL RPT

Report of Independent Registered
Public Accounting Firm

To the Board of Trustees and Shareholders SEI
Institutional Managed Trust:

In planning and performing our audits of the
financial statements of SEI Institutional Managed
Trust (the Trust), comprised of the Large Cap Fund,
Large Cap Value Fund, Large Cap Growth Fund, Large
Cap Index Fund (commencement of operations January
31, 2018), Tax-Managed Large Cap Fund, S&P 500
Index Fund, Small Cap Fund, Small Cap Value Fund,
Small Cap Growth Fund, Tax-Managed Small/Mid Cap
Fund, Mid-Cap Fund, U.S. Managed Volatility Fund,
Global Managed Volatility Fund, Tax-Managed Managed
Volatility Fund, Tax-Managed International Managed
Volatility Fund, Real Estate Fund, Enhanced Income
Fund, Core Fixed Income Fund, High Yield Bond Fund,
Conservative Income Fund, Tax-Free Conservative
Fund, Real Return Fund, Multi-Strategy Alternative
Fund, Multi-Asset Income Fund, Multi-Asset Capital
Stability Fund and the Long/Short Alternative Fund
(twenty-six of the twenty-nine funds comprising the
Trust), and the consolidated financial statements
of the Dynamic Asset Allocation Fund, Multi-Asset
Accumulation Fund, and the Multi-Asset Inflation
Managed Fund (three of the twenty-nine funds
comprising the Trust) as of and for the year ended
September 30, 2018, except for the Large Cap Index
Fund for which the date is the period from January
31, 2018 (commencement of operations) through
September 30, 2018, in accordance with the
standards of the Public Company Accounting
Oversight Board (United States), 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 express no such opinion.

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 companys
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 companys
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 Trustees of the company; and (3)
provide reasonable assurance regarding prevention
or timely detection of unauthorized acquisition,
use, or disposition of the companys 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 Funds 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 that might be material weaknesses
under standards established by the Public Company
Accounting Oversight Board (United States).
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 September 30,
2018.

This report is intended solely for the information
and use of management and the Board of Trustees of
SEI Institutional Investment Trust 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/ KPMG LLP
Philadelphia, Pennsylvania
November 29, 2018

FINANCIAL SUPPORT

SEI Institutional Managed Trust
Form N-CEN
Item G.1.a.ii.  Provision for Financial Support
Fund: SIMT Large Cap Index Fund
On April 20, 2018, SEI Investments Management
Corporation (SIMC), investment adviser to the SEI
Institutional Managed Trust Large Cap Index Fund
(the Fund), made a capital contribution to the Fund
in the amount of $330,025. The Fund commenced its
operations on January 31, 2018.  The capital
contribution offset the Funds performance deviation
from its benchmark that resulted from an unusually
large unanticipated cash flow that came into the
Fund shortly after its launch.