Report of Independent Registered Public Accounting Firm 

To the Shareholders of Banking Fund, Basic Materials Fund, Biotechnology Fund, Consumer Products Fund, Electronics Fund, Energy Fund, Energy Services Fund, Financial Services Fund, Health Care Fund, Internet Fund, Leisure Fund, Precious Metals Fund, Real Estate Fund, Retailing Fund, Technology Fund, Telecommunications Fund, Transportation Fund, Utilities Fund, Dow Jones Industrial Average; Fund, Nova Fund, S&P 500; Fund, Inverse S&P 500; Strategy Fund, Monthly Rebalance NASDAQ-100; 2x Strategy Fund, NASDAQ-100 Fund, Inverse NASDAQ-100; Strategy Fund, Mid-Cap 1.5x Strategy Fund, Inverse Mid-Cap Strategy Fund, Russell 2000; 1.5x Strategy Fund, Russell 2000; Fund, Inverse Russell 2000; Strategy Fund, S&P 500® Pure Growth Fund, S&P 500® Pure Value Fund, S&P MidCap 400® Pure Growth Fund, S&P MidCap 400® Pure Value Fund, S&P SmallCap 600® Pure Growth Fund, S&P SmallCap 600® Pure Value Fund, Emerging Markets Bond Strategy Fund, Government Long Bond 1.2x Strategy Fund, Inverse Government Long Bond Strategy Fund, High Yield Strategy Fund, Inverse High Yield Strategy Fund, Emerging Market 2x Strategy Fund, Inverse Emerging Markets 2x Strategy Fund, Europe 1.25x Strategy Fund, Japan 2x Strategy Fund, Strengthening Dollar 2x Strategy Fund, Weakening Dollar 2x Strategy Fund and U.S. Government Money Market Fund, and the Board of Trustees of Rydex Series Funds 

In planning and performing our audits of the financial statements of Banking Fund, Basic Materials Fund, Biotechnology Fund, Consumer Products Fund, Electronics Fund, Energy Fund, Energy Services Fund, Financial Services Fund, Health Care Fund, Internet Fund, Leisure Fund, Precious Metals Fund, Real Estate Fund, Retailing Fund, Technology Fund, Telecommunications Fund, Transportation Fund, Utilities Fund, Dow Jones Industrial Average; Fund, Nova Fund, S&P 500; Fund, Inverse S&P 500; Strategy Fund, Monthly Rebalance NASDAQ-100; 2x Strategy Fund, NASDAQ-100 Fund, Inverse NASDAQ-100; Strategy Fund, Mid-Cap 1.5x Strategy Fund, Inverse Mid-Cap Strategy Fund, Russell 2000; 1.5x Strategy Fund, Russell 2000; Fund, Inverse Russell 2000; Strategy Fund, S&P 500® Pure Growth Fund, S&P 500® Pure Value Fund, S&P MidCap 400® Pure Growth Fund, S&P MidCap 400® Pure Value Fund, S&P SmallCap 600® Pure Growth Fund, S&P SmallCap 600® Pure Value Fund, Emerging Markets Bond Strategy Fund, Government Long Bond 1.2x Strategy Fund, Inverse Government Long Bond Strategy Fund, High Yield Strategy Fund, Inverse High Yield Strategy Fund, Emerging Market 2x Strategy Fund, Inverse Emerging Markets 2x Strategy Fund, Europe 1.25x Strategy Fund, Japan 2x Strategy Fund, Strengthening Dollar 2x Strategy Fund, Weakening Dollar 2x Strategy Fund and U.S. Government Money Market Fund, (collectively referred to as the “Funds”), (forty-eight of the funds constituting Rydex Series Funds (the “Trust”), as of and for the year ended March 31, 2026, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), we considered the Trust’s internal control over financial reporting, including controls over safeguarding securities, as a basis for designing our auditing procedures for the purpose of expressing our opinions 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 Trust’s internal control over financial reporting. Accordingly, we express no such opinion.  

The management of the Trust 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 U.S. 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 U.S. 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 Trust’s annual or interim financial statements will not be prevented or detected on a timely basis.  

Our consideration of the Trust’s 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 PCAOB. However, we noted no deficiencies in the Trust’s 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 March 31, 2026. 

This report is intended solely for the information and use of management and the Board of Trustees of Rydex Series 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/Ernst & Young LLP
Tysons, Virginia 
May 28, 2026