Note 1 Basis of Accounting

UBS AG’s (“UBS”) consolidated financial statements (“the Financial Statements”) are prepared in accordance with International Financial Reporting Standards (IFRS) and stated in Swiss francs (CHF). These Financial Statements are presented in accordance with IAS 34 “Interim Financial Reporting”. In preparing the interim Financial Statements, the same accounting principles and methods of computation are applied as in the Financial Statements at 31 December 2003 and for the year then ended except for the changes set out below. These interim Financial Statements should be read in conjunction with the audited Financial Statements included in the UBS Financial Report 2003.

UBS sponsors the formation of companies, which may or may not be directly or indirectly owned subsidiaries, for the purpose of asset securitization transactions and to accomplish certain narrow and well-defined objectives. These companies may acquire assets directly or indirectly from UBS or its affiliates. Some of these companies are bankruptcy-remote entities whose assets are not available to satisfy the claims of creditors of UBS or any of its subsidiaries. Such companies are consolidated in the Financial Statements when the relationship between UBS and the company indicates that it is controlled by UBS.

Changes in Accounting Policies

Financial Instruments
On 1 January 2004, UBS adopted revised IAS 32 “Financial Instruments: Disclosure and Presentation” and revised IAS 39 “Financial Instruments: Recognition and Measurement” which were applied retrospectively to all financial instruments affected within the context of the two standards with the exception of the guidance relating to derecognition of financial assets and liabilities, which is applied prospectively. As a result of adopting the revised standards, UBS has restated prior period comparative information, as if the revised accounting standards had been in effect since the beginning of 2002, the earliest comparative prior period that will be presented with the audited Financial Statements to be included in the UBS Financial Report 2004.

Revised IAS 32 amends the accounting for certain derivative contracts linked to an entity’s own shares. Physically settled written put options and forward purchase contracts with UBS shares as underlying are recorded as liabilities, where at inception the present value of the obligation under the contract is debited against equity. The liability is subsequently accreted to the settlement amount using the effective interest rate method, thereby recording interest expense over the life of the contract. UBS currently has physically settled written put options linked to own shares that are now accounted for as liabilities. Liabilities of CHF 85 million at 30 June 2004, and CHF 49 million at 31 December 2003 were debited to shareholders’ equity due to written options. The impact on the income statement of all periods presented is insignificant. All other derivative contracts linked to own shares are accounted for as derivative instruments and are carried at fair value on the balance sheet under Positive replacement values or Negative replacement values.

Revised IAS 32 provides that netting is permitted only if, in addition to all other netting conditions, normal settlement is intended to take place on a net basis. In general, that condition is not met for derivative instruments and therefore replacement values are now reported on a gross basis. Replacement values of CHF 165,050 million that were previously offset have been affected and are now reported gross in the 31 December 2003 balance sheet.

Revised IAS 39 permits any financial instrument to be designated at inception, or at adoption of revised IAS 39, as carried at fair value through profit and loss. Upon adoption of revised IAS 39, UBS made that designation for the majority of its compound instruments issued. Previously, UBS separated the embedded derivative from the host contract and accounted for the separated derivative as a trading instrument. These instruments are now carried at fair value in their entirety with changes in fair value recorded in the income statement. The amounts are now included on the balance sheet within the line item Financial liabilities designated at fair value, with amounts of CHF 48,399 million at 30 June 2004 and CHF 35,286 million at 31 December 2003 being reported in that new line.

The guidance governing recognition and derecognition of a financial asset is considerably more complex under revised IAS 39 than previously and requires a multi-step decision process to determine whether derecognition is appropriate. UBS derecognizes financial assets for which it transfers the contractual rights to the cash flows and no longer retains any risk or reward coming from them nor maintains control over the financial assets. Accordingly, certain transactions are now accounted for as secured financing transactions instead of purchases or sales of trading portfolio assets with an accompanying swap derivative. The provisions of this guidance were applied prospectively as of 1 January 2004.

The effect of restating the income statement due to the adoption of revised IAS 32 and 39 on the comparative prior periods is as follows:

For the full years 2003 and 2002, net profit is reduced by CHF 82 million and CHF 24 million respectively. For the comparative second quarter of 2003, the effect on net profit was a reduction of CHF 35 million.

Investment properties
Effective 1 January 2004, UBS changed its accounting policy for investment property from historical cost less accumulated depreciation to the fair value model. All changes in the fair value of investment property are now recognized in the income statement, and depreciation expense is no longer recorded. Investment property is defined as property held exclusively to earn rental income and benefit from appreciation in value. Fair value of investment property is determined by appropriate valuation techniques employed in the real estate industry, taking into account the specific circumstances for each item.

This change required restatement of the 2002 and 2003 comparative financial years. The effects of the restatement were as follows: For the full year 2003, net profit was reduced by CHF 64 million and for the full year 2002 net profit was increased by CHF 19 million. For the comparative second quarter of 2003, the effect on net profit was a reduction of 67 million.

Credit risk losses incurred on OTC derivatives
Effective 1 January 2004, the method of accounting for credit risk losses incurred on over-thecounter (OTC) derivatives has been changed. All such credit risk losses are now reported in net trading income and are no longer reported in credit loss expense. This change did not affect net profit or earnings per share results. It did, however, affect segment reporting, as losses reported as credit loss expense were previously deferred over a three-year period in the Business Group segment reporting, whereas under the changed method of accounting, losses in trading income are not subject to such a deferral. In the segment report, therefore, losses on OTC derivatives are now reported as they are incurred. This change in accounting method affected to a minor extent certain balance sheet lines at 31 December 2003, which have been restated to conform to the current year presentation. The changed method of accounting had the following impact on the performance before tax of our Business Groups. In 2003, it reduced Wealth Management & Business Banking’s pre-tax performance by CHF 8 million. It raised the Investment Bank’s by CHF 37 million while Corporate Center’s fell by CHF 29 million. In 2002, the changed method lowered the Investment Bank’s pre-tax performance by CHF 28 million and raised Corporate Center’s by CHF 28 million. For the comparative second quarter of 2003, the effect on pre-tax performance was an increase of CHF 42 million at Investment Bank and a corresponding decrease at Corporate Center.

Acquisition of businesses

In second quarter 2004, UBS completed the acquisition of Laing & Cruickshank, a provider of wealth management services in the United Kingdom, and Scott Goodman Harris, an independent financial advisor in the United Kingdom, for an aggregate purchase price of CHF 386 million. The acquisitions were accounted for as business combinations. The aggregate purchase price has been tentatively allocated as follows: CHF 15 million to net tangible assets, CHF 110 million to identifiable intangible assets, and CHF 261 million to goodwill. The purchase price allocation will be finalized in the second half of 2004. Both acquisitions will benefit the operations of the Wealth Management business unit, to which all assets acquired and liabilities assumed have been allocated.

Top