<div id="readability-page-1"><div>RNS Number : 7305F Janus Henderson Investors 31 October 2025 FORM 8.3PUBLIC OPENING POSITION DISCLOSURE/DEALING DISCLOSURE BYA PERSON WITH INTERESTS IN RELEVANT SECURITIES REPRESENTING 1% OR MORERule 8.3 of the Takeover Code (the &#34;Code&#34;)1. KEY INFORMATION<div><table><tbody><tr><td>(a) Full name of discloser:</td><td>Janus Henderson Group plc</td></tr><tr><td>(b) Owner or controller of interests and short positions disclosed, if different from 1(a): The naming of nominee or vehicle companies is insufficient. For a trust, the trustee(s), settlor and beneficiaries must be named.</td><td></td></tr><tr><td>(c) Name of offeror/offeree in relation to whose relevant securities this form relates: Use a separate form for each offeror/offeree</td><td>Big Yellow Group PLC</td></tr><tr><td>(d) If an exempt fund manager connected with an offeror/offeree, state this and specify identity of offeror/offeree:</td><td></td></tr><tr><td>(e) Date position held/dealing undertaken: For an opening position disclosure, state the latest practicable date prior to the disclosure</td><td>30 October 2025</td></tr><tr><td>(f) In addition to the company in 1(c) above, is the discloser making disclosures in respect of any other party to the offer? If it is a cash offer or possible cash offer, state &#34;N/A&#34;</td><td>N/A</td></tr></tbody></table></div>2. POSITIONS OF THE PERSON MAKING THE DISCLOSUREIf 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.(a) Interests and short positions in the relevant securities of the offeror or offeree to which the disclosure relates following the dealing (if any)<div><table><tbody><tr><td>Class of relevant security:</td><td colspan="4">10p ordinary</td></tr><tr><td rowspan="2"></td><td colspan="2">Interests</td><td colspan="2">Short positions</td></tr><tr><td>Number</td><td>%</td><td>Number</td><td>%</td></tr><tr><td>(1) Relevant securities owned and/or controlled:</td><td>3,912,722*</td><td>1.99%</td><td></td><td></td></tr><tr><td>(2) Cash-settled derivatives:</td><td>38,293*</td><td>0.02%</td><td></td><td></td></tr><tr><td>(3) Stock-settled derivatives (including options) and agreements to purchase/sell:</td><td></td><td></td><td></td><td></td></tr><tr><td> TOTAL:</td><td>3,951,015*</td><td>2.01%</td><td></td><td></td></tr></tbody></table></div>*Janus Henderson Group Plc does not have discretion regarding voting decisions in respect of 388,497 shares that are included in the total above.All interests and all short positions should be disclosed.Details of any open stock-settled derivative positions (including traded options), 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 employee options)<ul><li>Class of relevant security in relation to which subscription right exists:</li><li>Details, including nature of the rights concerned and relevant percentages:</li></ul>3. DEALINGS (IF ANY) BY THE PERSON MAKING THE DISCLOSUREWhere 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.The currency of all prices and other monetary amounts should be stated.(a) Purchases and sales<div><table><tbody><tr><td>Class of relevant security</td><td>10p ordinary</td></tr><tr><td>Purchase/sale</td><td>Sale</td></tr><tr><td>Number of securities</td><td>17,960</td></tr><tr><td>Price per unit</td><td>GBP 11.2200</td></tr></tbody></table></div> (b) Cash-settled derivative transactions<ul><li>Class of relevant security</li><li>Product descriptione.g. CFD</li><li>Nature of dealinge.g. opening/closing a long/short position, increasing/reducing a long/short position</li><li>Number of reference securities</li><li>Price per unit</li></ul> (c) Stock-settled derivative transactions (including options)(i) Writing, selling, purchasing or varying<ul><li>Class of relevant security</li><li>Product description e.g. call option</li><li>Writing, purchasing, selling, varying etc.</li><li>Number of securities to which option relates</li><li>Exercise price per unit</li><li>Typee.g. American, European etc.</li><li>Expiry date</li><li>Option money paid/ received per unit</li></ul>(ii) Exercise<ul><li>Class of relevant security</li><li>Product descriptione.g. call option</li><li>Exercising/ exercised against</li><li>Number of securities</li><li>Exercise price per unit</li></ul>(d) Other dealings (including subscribing for new securities)<ul><li>Class of relevant security</li><li>Nature of dealinge.g. subscription, conversion</li><li>Details</li><li>Price per unit (if applicable)</li></ul>4. OTHER INFORMATION(a) Indemnity and other dealing arrangements<ul><li>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:Irrevocable commitments and letters of intent should not be included. If there are no such agreements, arrangements or understandings, state &#34;none&#34;</li><li>None</li></ul>(b) Agreements, arrangements or understandings relating to options or derivatives<ul><li>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 &#34;none&#34;</li><li>None</li></ul>(c) Attachments<ul><li>Is a Supplemental Form 8 (Open Positions) attached?</li><li>No</li></ul><div><table><tbody><tr><td>Date of disclosure:</td><td>31 October 2025</td></tr><tr><td>Contact name:</td><td>John Baker</td></tr><tr><td>Telephone number:</td><td>020 7818 3064</td></tr></tbody></table></div>Public disclosures under Rule 8 of the Code must be made to a Regulatory Information Service.The Panel's Market Surveillance Unit is available for consultation in relation to the Code's disclosure requirements on +44 (0) 20 7638 0129.The Code can be viewed on the Panel's website at www.thetakeoverpanel.org.uk.This information is provided by RNS, the news service of the London Stock Exchange. 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Janus Henderson Group plc disclosed its position in Big Yellow Group PLC, reporting ownership of 3,912,722 shares (1.99%) and cash-settled derivatives of 38,293 shares (0.02%). The total interest amounts to 3,951,015 shares (2.01%). Additionally, Janus Henderson sold 17,960 shares at GBP 11.22 each. The disclosure was made under Rule 8.3 of the Takeover Code on 31 October 2025, with no other agreements or arrangements reported.

REG - Janus Henderson Inv. Big Yellow Group PLC - Form 8.3 - Big Yellow Group PLC