Posting of Offer Document

London Stock Exchange
11 September 2000


NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION IN OR INTO AUSTRALIA, CANADA,
JAPAN OR THE UNITED STATES

                                   OM GROUP
                                   --------
                                       
                      OFFER FOR LONDON STOCK EXCHANGE PLC
                      -----------------------------------

OM announces the posting today of its Offer Document to LSE Shareholders, in
which OM sets out its blueprint for LSE and the terms of its Offer.  The
Directors of OM believe that the Offer is right for LSE and will benefit both
LSE Shareholders and LSE customers by:

*         offering full value to LSE Shareholders

*         securing LSE's position as the pre-eminent European secondary market
          for trading in both high growth and blue chip companies within a
          single market framework

*         reinforcing the retail market by making equity trading more
          accessible

*         strengthening LSE as the preferred market for initial public
          offerings in Europe

*         providing LSE with OM's state-of-the-art transaction technology to
          equip LSE with sufficient transaction capacity to meet comfortably
          the expected substantial growth in transaction volumes

*         targeting vertical efficiency between exchange, clearing and
          settlement functions

*         operating under clear principles of corporate governance and in open
          consultation with market participants

*         providing clarity and simplicity by avoiding regulatory compromise:
          the FSA will remain the sole regulatory authority for LSE

*         capitalising on LSE as an authoritative source of market information
          and developing new and profitable value-added information services

*         adding further sources of revenue by developing e-commerce
          businesses


Commenting, Per E. Larsson, President and Chief Executive Officer of OM, said:

'iX would have squandered London's potential.  It was flawed and discredited
and now it is time to focus on our alternative.  Our offer today brings state-
of-the-art technology, clarity, and real commercial drive that will secure
London as Europe's leading exchange.  Our mission now is to explain how OM
will realise this vision.  Talking and listening to LSE customers and
shareholders is our priority over the coming weeks.'

Terms of the Offer
------------------

Under the Offer, OM is offering LSE Shareholders 0.65 new OM Shares and
GBP7.00 in cash for each LSE share held.  On the basis of OM's closing share
price of SEK437 on 8 September 2000, the latest practicable date prior to this
announcement, and an exchange rate of SEK13.77:GBP1 as published in the
Financial Times on that date, this values each LSE Share at GBP27.63 and LSE
at approximately GBP820 million.  The value of the Offer represents a premium
of 17.6 per cent. to the closing price of an LSE Share on 25 August 2000 (the
closing price prior to LSE's announcement of OM's approach).

A Loan Note Alternative is available to eligible LSE Shareholders in respect
of the whole or part of the cash element of the Offer.  OM intends to seek a
secondary listing in London following the completion of the Offer.

Prior to announcing its Offer, OM met LSE's management and advisers with a
view to securing the recommendation of the Board of LSE for OM's proposal.
Although this initial approach was rejected OM continues to urge the LSE Board
to consider the commercial and technological advantages of a combination with
OM.

Changing LSE's Articles of Association
--------------------------------------

Neither OM's Offer, nor any other offer or merger proposal for LSE (including
the iX merger proposal), can be completed under the terms of LSE's existing
Articles of Association.  This is because the Articles currently prevent any
person, or group of persons acting in concert, from holding more than 4.9 per
cent. of the voting rights in LSE.

Therefore, in order for any offer or merger proposal to succeed, the Articles
of LSE need to be changed by LSE Shareholders in a general meeting and OM is
seeking the assistance of LSE Shareholders in requisitioning such a meeting.
The Offer Document posted today is accompanied by a form of requisition for
that purpose. The form of requisition may be completed and returned
independently of the Form of Acceptance in respect of the Offer.  LSE
Shareholders are urged to complete and return the form of requisition without
delay.

To accept the Offer
-----------------------

Forms of Acceptance in respect of the Offer should be received not later than
3.00 pm on 2 October 2000 (or such later time(s) and date(s) as OM may,
subject to The City Code on Takeovers and Mergers, decide).  Further copies of
the Offer Document and the Form of Acceptance are available from Capita IRG
plc by post or collection by hand from Capita IRG plc, New Issues Department,
PO Box 166, Bourne House, 34 Beckenham Road, Kent, BR3 4TH or by hand only
(during normal business hours) at 23 Ironmonger Lane, London EC2.

In addition, the Offer Document is available on OM's website at
www.omgroup.com.

ENQUIRIES

OM GROUP
--------
Olof Stenhammar, Chairman     [phone]
Per E. Larsson, President &   On 11 September 2000: [phone]
Chief Executive Officer       Thereafter: [phone]
Magnus Karlsson Bocker,       On 11 September 2000: [phone]
Executive Vice President      Thereafter: [phone]
Jakob Hakanson, Investor Relations      [phone]
Anna Eriksson, Corporate Communications [phone]

LAZARD                        [phone]
------
David Verey
Jonathan Dawson
Svante Adde                   [phone]


HILL & KNOWLTON
------------------
Anthony Payne                 [phone]
                              [phone]

The Directors of OM accept responsibility for the information contained in
this announcement and, to the best of their knowledge and belief (having taken
all reasonable care to ensure that such is the case), the information
contained in this announcement is in accordance with the facts and does not
omit anything likely to affect the import of such information.

Lazard, which is regulated in the UK by The Securities and Futures Authority
Limited, is acting for OM and no-one else in connection with the Offer and
will not be responsible to anyone other than OM for providing the protections
afforded to customers of Lazard or for giving advice in relation to the Offer.

Words and phrases defined in the Offer Document carry the same meanings in
this announcement.

The Offer is not being made, directly or indirectly, in or into or by the use
of the mail or any means or instrumentality of interstate or foreign commerce
of, or any facilities of a national securities exchange of the United States
nor is it being made in Canada, Japan or Australia.  Neither the new OM Shares
nor the Loan Notes will be registered under the United States Securities Act
of 1933 (as amended).  Further details in relation to overseas shareholders
are contained in the Offer Document.