FORM 8.3

PUBLIC OPENING POSITION DISCLOSURE/DEALING DISCLOSURE BY

A PERSON WITH INTERESTS IN RELEVANT SECURITIES REPRESENTING 1% OR MORE

Rule 8.3 of the Takeover Code (the “Code”)

1.         KEY INFORMATION

(a) Identity of the person whose positions/dealings are being disclosed: Magnetar Capital Partners LP
(b) Owner or controller of interests and short positions disclosed, if different from 1(a):
     The naming of nominee or vehicle companies is insufficient		 N/A
(c) Name of offeror/offeree in relation to whose relevant securities this form relates:
     Use a separate form for each offeror/offeree		CME Group Inc.
(d) If an exempt fund manager connected with an offeror/offeree, state this and specify identity of offeror/offeree: N/A
(e) Date position held/dealing undertaken: July 16, 2018
(f)  Has the discloser previously disclosed, or are they today disclosing, under the Code in respect of any other party to this offer? Yes – NEX Group plc

2.         POSITIONS OF THE PERSON MAKING THE DISCLOSURE

(a)        Interests and short positions in the relevant securities of the offeror or offeree to which the disclosure relates following the dealing (if any)

Class of relevant security: USD 0.01 Class A common stock
ISIN: US12572Q1058
InterestsShort positions
Number%Number%
(1) Relevant securities owned and/or controlled:171,011.05%
(2) Derivatives (other than options):22,584.01%
(3) Options and agreements to purchase/sell:

     TOTAL:		193,595.06%

All interests and all short positions should be disclosed.

Details of any open derivative or option positions, or agreements to purchase or sell relevant securities, should be given on a Supplemental Form 8 (Open Positions).

(b)        Rights to subscribe for new securities (including directors’ and other executive options)

Class of relevant security in relation to which subscription right exists:
Details, including nature of the rights concerned and relevant percentages:

If there are positions or rights to subscribe to disclose in more than one class of relevant securities of the offeror or offeree named in 1(c), copy table 2(a) or (b) (as appropriate) for each additional class of relevant security.

3.         DEALINGS (IF ANY) BY THE PERSON MAKING THE DISCLOSURE

(a)        Purchases and sales

Class of relevant securityPurchase/saleNumber of securitiesPrice per unit
Ordinary shares Sale 22 168.1982
Ordinary shares Sale 28 168.0564
Ordinary shares Sale 28 168.1714
Ordinary shares Sale 32 167.9488
Ordinary shares Sale 33 168.1342
Ordinary shares Sale 34 168.1368
Ordinary shares Sale 35 168.0786
Ordinary shares Sale 36 167.8867
Ordinary shares Sale 37 168.0273
Ordinary shares Sale 38 168.0934
Ordinary shares Sale 38 168.1411
Ordinary shares Sale 38 167.5729
Ordinary shares Sale 38 168.0816
Ordinary shares Sale 39 168.2108
Ordinary shares Sale 39 167.7244
Ordinary shares Sale 40 167.9628
Ordinary shares Sale 41 168.2866
Ordinary shares Sale 41 168.0793
Ordinary shares Sale 45 167.88
Ordinary shares Sale 50 168.236
Ordinary shares Sale 50 167.7484
Ordinary shares Sale 54 168.0685
Ordinary shares Sale 84 168.08
Ordinary shares Sale 108 168.0678
Ordinary shares Sale 122 168.2084
Ordinary shares Sale 128 167.9902

 (b)       Derivatives transactions (other than options)

Class of relevant securityProduct description
e.g. CFD		Nature of dealing
e.g. opening/closing a long/short position, increasing/reducing a long/short position		Number of reference securitiesPrice per unit

 (c)       Options transactions in respect of existing securities

(i)         Writing, selling, purchasing or varying

Class of relevant securityProduct description e.g. call optionWriting, purchasing, selling, varying etc.Number of securities to which option relatesExercise price per unitType
e.g. American, European etc.		Expiry dateOption money paid/ received per unit

(ii)        Exercising

Class of relevant securityProduct description
e.g. call option		Number of securitiesExercise price per unit

(d)        Other dealings (including subscribing for new securities)

Class of relevant securityNature of dealing
e.g. subscription, conversion		DetailsPrice per unit (if applicable)

The currency of all prices and other monetary amounts should be stated.

Where there have been dealings in more than one class of relevant securities of the offeror or offeree named in 1(c), copy table 3(a), (b), (c) or (d) (as appropriate) for each additional class of relevant security dealt in.

4.         OTHER INFORMATION

(a)        Indemnity and other dealing arrangements

Details of any indemnity or option arrangement, or any agreement or understanding, formal or informal, relating to relevant securities which may be an inducement to deal or refrain from dealing entered into by the person making the disclosure and any party to the offer or any person acting in concert with a party to the offer:
If there are no such agreements, arrangements or understandings, state “none”

None

(b)        Agreements, arrangements or understandings relating to options or derivatives

Details of any agreement, arrangement or understanding, formal or informal, between the person making the disclosure and any other person relating to:
(i)  the voting rights of any relevant securities under any option; or
(ii) the voting rights or future acquisition or disposal of any relevant securities to which any derivative is referenced:
If there are no such agreements, arrangements or understandings, state “none”
None

(c)        Attachments

Is a Supplemental Form 8 (Open Positions) attached? No

   

Date of disclosure:July 17, 2018
Contact name:Audrey Newsom
Telephone number:847-905-4693

            Public disclosures under Rule 8 of the Code must be made to a Regulatory Information Service and must also be emailed to the Takeover Panel atmonitoring@disclosure.org.uk.  The Panel’s Market Surveillance Unit is available for consultation in relation to the Code’s dealing disclosure requirements on +44 (0)20 7638 0129.

The Code can be viewed on the Panel’s website atwww.thetakeoverpanel.org.uk.