Pursuant to Section 19(b)(1) of the Securities Exchange Act of 1934 (“Act” or “Exchange Act”) ^[1] and Rule 19b-4 thereunder,^[2] notice is hereby given that on July 8, 2008, Chicago Board Options Exchange, Incorporated (“CBOE” or the “Exchange”) filed with the Securities and Exchange Commission (“Commission”) the proposed rule change as described in Items I, II, and III below, which Items have been substantially prepared by CBOE. CBOE has filed the proposal as a “non-controversial” proposed rule change pursuant to Section 19(b)(3)(A) of the Act ^[3] and Rule 19b-4(f)(6) thereunder,^[4] which renders the proposed rule change effective upon filing with the Commission. The Commission is publishing this notice to solicit comments on the proposed rule change from interested persons.

I. Self-Regulatory Organization's Statement of the Terms of Substance of the Proposed Rule Change

CBOE proposes to make permanent the customer portfolio margin program codified in Exchange Rules 9.15(c)— Delivery of Current Options Disclosure Documents, 12.4— Portfolio Margin, 13.5— Customer Portfolio Margin Accounts, and 15.8A— Risk Analysis of Portfolio Margin Accounts. CBOE is not proposing any textual changes to its Constitution or Rules. The text of the proposed rule change is available on the Exchange's website ( http://www.cboe.org/​legal), at the Exchange's Office of the Secretary and at the Commission's Public Reference Room.

II. Self-Regulatory Organization's Statement of the Purpose of, and Statutory Basis for, the Proposed Rule Change

In its filing with the Commission, CBOE included statements concerning the purpose of and basis for the proposed rule change and discussed any comments it received on the proposed rule change. The text of these statements may be examined at the places specified in Item IV below. CBOE has prepared summaries, set forth in sections A, B, and C below, of the most significant aspects of such statements.

A. Self-Regulatory Organization's Statement of the Purpose of, and Statutory Basis for, the Proposed Rule Change

1. Purpose

The Exchange's customer portfolio margining program, as previously approved by the Commission, allows broker-dealers, for eligible securities, to compute customer margin requirements based on a portfolio margining methodology.^[5] The portfolio margining program is operating under a pilot program that is scheduled to expire on July 31, 2008.^[6]

Amendments to the rules effective April 2, 2007, made equities, equity options, narrow-based index options, unlisted derivatives and security futures eligible for portfolio margining.^[7] The Exchange believes it has had sufficient time to assess the operation of the pilot program and has not encountered any problems or difficulties relating to the pilot program since its inception. For this reason, the Exchange proposes that the Commission approve the pilot program on a permanent basis.^[8]

2. Statutory Basis

Because the portfolio margin pilot program has promoted greater reasonableness, accuracy and efficiency with respect to margin requirements and better aligns margin requirements with actual risk, the Exchange believes that this proposed rule change is consistent with Section 6(b) of the Exchange Act,^[9] in general, and furthers the objectives of Section 6(b)(5) of the Act ^[10] in particular, in that it is designed to perfect the mechanism of a free and open market, and to protect investors and the public interest.

B. Self-Regulatory Organization's Statement on Burden on Competition

CBOE does not believe that the proposed rule change will impose any burden on competition that is not necessary or appropriate in furtherance of purposes of the Act.

C. Self-Regulatory Organization's Statement on Comments on the Proposed Rule Change Received From Members, Participants or Others

No written comments were solicited or received with respect to the proposed rule change.

III. Date of Effectiveness of the Proposed Rule Change and Timing for Commission Action

Because the forgoing proposed rule change does not: (i) Significantly affect the protection of investors or the public interest; (ii) impose any significant burden on competition; and (iii) become operative for 30 days after the date of the filing, or such shorter time as the Commission may designate if consistent with the protection of investors and the public interest, it has become effective pursuant to Section 19(b)(3)(A) of the Act ^[11] and Rule 19b-4(f)(6) thereunder.^[12]

A proposed rule change filed under Rule 19b-4(f)(6) normally may not become operative prior to 30 days after the date of filing. However, Rule 19b-4(f)(6)(iii) permits the Commission to designate a shorter time if such action is consistent with the protection of investors and the public interest. The Exchange requests that the Commission waive the 30-day operative delay, which would make the change operative upon filing. The Commission believes that waiving the 30-day operative delay is consistent with the protection of investors and the public interest because such waiver will allow the customer portfolio margining program to continue uninterrupted as it would otherwise expire on July 31, 2008.^[13] Accordingly, the Commission designates the proposed rule change effective upon filing with the Commission.

At any time within 60 days of the filing of the proposed rule change, the Commission may summarily abrogate such rule change if it appears to the Commission that such action is necessary or appropriate in the public interest, for the protection of investors, or otherwise in furtherance of the purposes of the Act.

IV. Solicitation of Comments

Interested persons are invited to submit written data, views, and arguments concerning the foregoing, including whether the proposed rule change is consistent with the Act. Comments may be submitted by any of the following methods:

Electronic Comments

• Use the Commission's Internet comment form (http://www.sec.gov/​rules/​sro.shtml); or
• Send an e-mail torule-comments@sec.gov. Please include File Number SR-CBOE-2008-73 on the subject line.

Paper Comments

• Send paper comments in triplicate to Secretary, Securities and Exchange Commission, 100 F Street, NE., Washington, DC 20549-1090.

All submissions should refer to File Number SR-CBOE-2008-73. This file number should be included on the subject line if e-mail is used. To help the Commission process and review your comments more efficiently, please use only one method. The Commission will post all comments on the Commission's Internet Web site ( http://www.sec.gov/​rules/​sro.shtml). Copies of the submission, all subsequent amendments, all written statements with respect to the proposed rule change that are filed with the Commission, and all written communications relating to the proposed rule change between the Commission and any person, other than those that may be withheld from the public in accordance with the provisions of 5 U.S.C. 552, will be available for inspection and copying in the Commission's Public Reference Room, 100 F Street, NE., Washington, DC 20549 on official business days between the hours of 10 a.m. and 3 p.m. Copies of such filing also will be available for inspection and copying at the principal office of CBOE. All comments received will be posted without change; the Commission does not edit personal identifying information from submissions. You should submit only information that you wish to make available publicly. All submissions should refer to File Number SR-CBOE-2008-73 and should be submitted on or before August 26, 2008.