Chiron and Ciba-Geigy form unique global partnership in biotechnology; Ciba to hold 49.9% interest in Chiron following tender offer for 11.9 million shares at $117 per share and exchange of vaccines, diagnostics interests for new Chiron shares; total consideration is $2.1 billion; World center of biotech excellence and leading global health care company join complementary strengths and expand R&D collaboration; Chiron to continue to operate.

EMERYVILLE, CA (USA) AND BASLE, SWITZERLAND--(BUSINESS WIRE)-- Nov. 21, 1994--Dr. William Rutter, Chairman of Chiron Corporation (NASDAQ:CHIR), and Dr. Alex Krauer, Chairman and Chief Executive Officer of Ciba-Geigy Ltd., today announced that the two companies have signed definitive agreements to form a strategic partnership between Chiron and Ciba.

The partnership involves a significant collaboration which will leverage the companies' complementary strengths to discover, develop, produce and market biotechnology and other health care products on a global scale. While working with Ciba in a collaborative relationship, Chiron will continue to operate independently and, where appropriate, pursue projects outside the partnership to optimize the value of its technologies and develop its businesses.

Commenting on their new partnership in a joint statement, Drs. Krauer and Rutter said: "In the rapidly changing health care marketplace and global environment, Chiron and Ciba share a similar strategic focus and compatible values: growth through scientific and commercial innovation. This agreement expands the long-standing and productive relationship between Chiron and Ciba -- which has included our successful Biocine joint ventures in vaccine development -- into a new paradigm for partnership: strategic cooperation between two independent but complementary organizations.

"We will address a current, unique opportunity through the formation of an alliance between a world center of biotech excellence and a leading global health care company. We feel this alliance will benefit our shareholders, collaborators and employees, as well as our customers."

To execute this alliance, Ciba will commence a tender offer for approximately 11.9 million shares of Chiron common stock, representing approximately 37.3% of Chiron's shares not owned by Ciba, at a price of $117 per share. These shares, when combined with 1.4 million Chiron shares already held by Ciba, and 6.6 million new common shares issued by Chiron to Ciba in exchange for Ciba's worldwide Ciba Corning Diagnostics (CCD) business and its 50 percent interest in The Biocine Company and Biocine SpA (which are joint vaccine ventures with Chiron), will give Ciba a 49.9% stake in Chiron.

Ciba's contribution to the partnership also includes:

-- a tradition of excellence in research;

-- strong financial resources; and

-- the broad experience of a global organization in the management of marketing, manufacturing and registration capabilities for health care products.

To this partnership, Chiron brings:

-- worldclass science and access to new technologies;

-- a creative, entrepreneurial culture;

-- newly enhanced, substantial business positions in four attractive markets: diagnostics, vaccines, therapeutics (with an emphasis on oncology and infectious diseases) and the surgical correction of vision; and

-- unlimited potential for future growth in shareholder value.

This new paradigm for partnership will enhance the competitiveness of both companies by:

-- building on Chiron's capabilities to act as a global platform for new business opportunities, especially in vaccines and diagnostics, as well as other leading-edge biotechnology ventures;

-- expanding collaboration in the areas of research and development, manufacturing, supply and marketing; and

-- more aggressive development of both biological and novel chemical technologies to accelerate the market introductions of new medical innovations.

Under the terms of the agreement, Dr. Rutter will join the Ciba Board of Directors. Dr. Krauer will join the Chiron Board, as one of the three Ciba directors.

               Detailed terms of the partnership

    The terms of the transaction that will create the partnership
include the following:

Financial

    -- Ciba, which currently holds approximately 1.4 million of
Chiron's outstanding common stock, will acquire an additional
approximately 18.5 million shares and as a result will hold a total
of about 49.9%, or about 20 million, of Chiron's shares.

      --     To accomplish this, Ciba will commence a tender
             offer for approximately 11.9 million shares at
             $117 per share, representing approximately
             37.3% of Chiron's shares not owned by Ciba.
      --     Ciba also will exchange its worldwide Ciba
             Corning Diagnostics (CCD) business and its 50%
             interest in The Biocine Company and Biocine
             SpA, which are joint vaccine ventures with
             Chiron, for 6.6 million newly-issued Chiron shares.
      --     CCD will continue as a separate division of
             Chiron and will be headed by its current president,
             William Zadel.  As part of the agreement, $100
             million in debt will remain on the CCD balance sheet.
      --     After the transaction, Chiron will have
             approximately 40 million common shares
             outstanding.  The 20 million shares not owned by
             Ciba will continue to trade freely.
      --     Chiron, at its option, may issue to Ciba up to
             $500 million of new equity.
      --     Ciba has also agreed to guarantee $425 million of
             new debt for Chiron, subject to certain conditions
             and Ciba approval rights.
      --     As part of these transactions, Ciba has agreed that
             it will not buy or offer to buy additional shares in
             Chiron for five years, unless required to maintain
             its 49.9% ownership position in Chiron.  After
             such time, Ciba may increase its ownership to
             55% of Chiron by purchasing additional common
             shares in the open market or through a transaction
             with Chiron.

Technology collaborations

    -- Ciba and Chiron have broadly agreed to cooperate in marketing,
manufacturing and research and development collaborations.
Specifically, the agreement includes the following provisions:
      --     a framework for pursuing new scientific
             collaborations;
      --     reciprocal right of first negotiation with respect to
             manufacturing of certain new products; and
      --     a reciprocal right of first offer with respect to the
             marketing of certain new products.

    -- The parties are now negotiating a first, specific collaboration
regarding combinatorial libraries.  Chiron and Ciba have also
identified a series of areas of mutual interest to explore during the
first year of the relationship.
    -- Ciba has agreed to provide at least $250 million and up to $300
million (contingent upon a reduction in the amount of debt guaranteed
by Ciba on behalf of Chiron) over five years for support of research
at Chiron.  Repayment will be made via cash, equity or royalties.

Governance

    -- The agreement provides for the Chiron board to be expanded from
eight to eleven members, with Ciba appointing three new directors.
    -- In addition, for certain classes of actions, if they exceed
specified levels, Ciba and its directors will have approval rights.
These actions include major capital markets transactions and major
acquisitions.  In addition, together with the independent directors,
Ciba directors must approve Chiron's strategic plan.

Conditions and Effects on Ciba's and Chiron's Earnings

    -- The transaction is subject to a number of conditions, including
the successful completion of the tender offer, clearance under the
Hart-Scott-Rodino Act and other closing conditions specified in the
agreements.  It is expected to be completed in early 1995.
    -- Ciba anticipates that the transaction will result in minimal
dilution to earnings.
    -- Chiron anticipates that the completion of the transaction may
give rise to a charge for the acquisition of in-process technology
or for other expenses associated with the transaction, but is not
currently able to predict its magnitude.

Drs. Rutter and Krauer emphasize potential for new collaboration

The nucleus for the partnership will be Chiron's existing operations headquartered in Emeryville, California. Following the completion of the transaction, Chiron will have approximately 6,000 employees.

Dr. Rutter and Dr. Krauer concluded, "As preferred partners, we will draw on the respective strengths of the two organizations, while allowing the character and identities of both to flourish. The two companies share a mutual respect, a willingness to cooperate to achieve common goals, and the belief that differences are strengths if managed properly. Importantly, both companies also believe strongly that our success springs from the creativity and dedication of our employees, and we recognize the contributions made by people throughout both organizations in making this new partnership possible."

Ciba-Geigy Ltd. of Basle, Switzerland is a leading worldwide biological and chemical group with 1993 sales of SFr. 22,647 million ($15,302 million). Ciba's Pharmaceuticals Division with 1993 sales of SFr. 6,599 million ($4,459 million), has branches, joint ventures, scientific offices and agencies in more than 190 countries. Ciba-Geigy Corp. of Ardsley, N.Y., a wholly-owned subsidiary of Ciba-Geigy Ltd., is a leading developer and manufacturer of health care and agricultural products and specialty chemicals for industry. Its Ciba Pharmaceuticals Division is dedicated to discovering, developing, manufacturing and marketing innovative pharmaceuticals that meet unmet medical needs and improve patients' quality of life.

Chiron Corporation has been headquartered in Emeryville, California, in the San Francisco Bay area since its founding in 1981. It has a history as a research leader, and it currently has more products in clinical trials than any other biotechnology company. Chiron is building a healthcare business that addresses needs in several markets: diagnostics, including immunodiagnostics and bDNA probe assays; vaccines, emphasizing adult and pediatric infectious diseases; therapeutics, with an emphasis on oncology, endocrinology and serious infectious and other diseases requiring critical care; and ophthalmic products for the surgical correction of vision.

CONTACT: For Ciba-Geigy

              Media
              US: David Taylor [phone]
              Basle: Kai Romot 41-61-696-6580
              Investment Community
              US: Joe Schepers [phone]
              Basle: Andre Haegi 41-61-697-7507
              For Chiron:
              Media: Larry Kurtz
              [phone]
              Fax [phone]
              Investment Community:  Same