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: May 18, 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:130,783.04%
(2) Derivatives (other than options):21,909.01%
(3) Options and agreements to purchase/sell:

     TOTAL:		152,692.05%

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 Purchase 5 159.5
Ordinary shares Purchase 43 160.1584
Ordinary shares Purchase 44 160.5523
Ordinary shares Purchase 46 159.47
Ordinary shares Purchase 57 159.4996
Ordinary shares Purchase 63 159.62
Ordinary shares Purchase 66 159.5806
Ordinary shares Purchase 68 160.3985
Ordinary shares Purchase 70 159.673
Ordinary shares Purchase 71 160.2152
Ordinary shares Purchase 72 160.1406
Ordinary shares Purchase 76 159.8121
Ordinary shares Purchase 78 159.749
Ordinary shares Purchase 79 159.8119
Ordinary shares Purchase 81 159.4502
Ordinary shares Purchase 81 159.5543
Ordinary shares Purchase 83 159.9418
Ordinary shares Purchase 85 159.6008
Ordinary shares Purchase 90 160.2389
Ordinary shares Purchase 163 159.49
Ordinary shares Purchase 175 159.5673
Ordinary shares Purchase 190 159.5188
Ordinary shares Purchase 194 159.49
Ordinary shares Purchase 224 159.4218
Ordinary shares Purchase 233 160.3533

 (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:May 21, 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.