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                                                                     Exhibit 8.2


                                 [Letterhead of]

                             CRAVATH, SWAINE & MOORE
                                [New York Office]






                                                             September 21, 2000




Ladies and Gentlemen:

                  We have acted as tax counsel for Paine Webber Group Inc., a
Delaware corporation ("PaineWebber"), in connection with the proposed merger
(the "Merger") of PaineWebber with and into Neptune Merger Subsidiary, Inc.
("Neptune Merger Subsidiary"), a Delaware corporation and wholly owned direct
subsidiary of UBS AG, a Swiss corporation ("UBS"), pursuant to an Agreement and
Plan of Merger dated as of July 12, 2000 (the "Merger Agreement"). Any
capitalized term used but not defined herein shall have the meaning given to
such term in the Merger Agreement.

                  In that connection, you have requested our opinion regarding
certain United States federal income tax consequences of the Merger. In
providing our opinion, we have examined the Merger Agreement, the registration
statement on Form F-4 (the "Registration Statement") dated as of the date
hereof, which includes the Joint Proxy Statement and Prospectus of PaineWebber
and UBS (the "Proxy Statement/Prospectus"), and such other documents,
instruments and corporate records as we have deemed necessary or appropriate for
purposes of our opinion. In addition, we have assumed that (i) the Merger will
be consummated as a direct merger of PaineWebber with and into Neptune Merger
Subsidiary and otherwise in the manner contemplated by the Proxy
Statement/Prospectus and in accordance with the provisions of the Merger
Agreement, (ii) the statements concerning the Merger set forth in the Merger
Agreement and the Proxy Statement/Prospectus are and will remain true, correct
and complete, (iii) the representations made to us by PaineWebber and UBS in
their respective letters to us each dated as of the date hereof and delivered to
us for purposes of this opinion are and will as of the date of the Merger remain
true, correct and complete (such letters, the "Representation Letters") and (iv)
any representations made in the Representation Letters
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or in the Merger Agreement "to the best knowledge of" or similarly qualified are
true, correct and complete without such qualification.

                  In our examination of documents, we have assumed, with your
consent, that (i) all documents submitted to us are authentic originals, or if
submitted as photocopies, that they faithfully reproduce the originals thereof;
(ii) all such documents have been or will be duly executed to the extent
required; (iii) all representations and statements set forth in such documents
are true and correct; (iv) any representation or statement made as a belief or
made "to the knowledge of," or similarly qualified is correct and accurate
without such qualification and (v) all obligations imposed by any such documents
on the parties thereto have been or will be performed or satisfied in accordance
with their terms.

                  If any of the above-described assumptions is untrue for any
reason or if the Merger is consummated in a manner that is inconsistent with the
manner in which it is described in the Merger Agreement and Proxy
Statement/Prospectus, our opinion as expressed below may be adversely affected
and may not be relied upon.

                  Based on the foregoing, in our opinion, for U.S. federal
income tax purposes (i) the Merger will qualify as a "reorganization" under
Section 368(a) of the Internal Revenue Code of 1986 (the "Code"), (ii) UBS,
Neptune Merger Subsidiary and PaineWebber will each be a "party" to such
reorganization under Section 368(b) of the Code, (iii) UBS will, as to each
eligible PaineWebber stockholder, be treated as a corporation under Section
367(a) of the Code, and (iv) an eligible PaineWebber stockholder will not
recognize gain or loss for United States federal income tax purposes in
connection with the receipt of UBS ordinary shares exchanged for PaineWebber
common stock pursuant to the Merger, except with respect to cash received in
lieu of fractional UBS ordinary shares.

                  The opinion expressed herein is based upon existing statutory,
regulatory and judicial authority, any of which may be changed at any time with
retroactive effect. Any change in applicable laws or the facts and circumstances
surrounding the Merger, or any inaccuracy in the statements, facts, assumptions
or representations upon which we have relied, may affect the continuing validity
of our opinion as set forth herein. We assume no responsibility to inform you of
any such change or inaccuracy that may occur or come to our attention. Finally,
our opinion is limited to the tax matters specifically covered hereby, and we
have not been asked to address, nor have we addressed, any other tax
consequences of the Merger or any other transaction.

                  This opinion is being provided for the benefit of PaineWebber
so that PaineWebber may comply with its obligation under the federal securities
laws. We consent to the filing of this opinion as an exhibit to the Registration
Statement and to the reference to our firm name therein. In giving this consent,
we do not admit that we are within the
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category of persons whose consent is required under Section 7 of the Securities
Act of 1933, as amended, or the rules or regulations of the Securities and
Exchange Commission promulgated thereunder.


                                            Very truly yours,

                                            Cravath, Swaine & Moore



Paine Webber Group Inc.
      1285 Avenue of the Americas
            New York, NY 10019