PIMCO FUNDS
497, 1998-04-06
Previous: PIMCO FUNDS, 497, 1998-04-06
Next: PIMCO FUNDS, 497, 1998-04-06



<PAGE>
 

                   PIMCO Funds Prospectus
       

Pacific            SHORT-TERM BOND FUNDS                                      
Investment         Short-Term Fund                                           
Management         Low Duration Fund  
Series:Class
D Shares           INTERMEDIATE-TERM BOND FUNDS        
                   Real Return Bond Fund              
April 8, 1998      Total Return Fund    
                   Total Return Mortgage Fund                                   
                   High Yield Fund                    
                                                                               
                   LONG-TERM BOND FUNDS                                        
                   Municipal Bond Fund                
                                                       
                   INTERNATIONAL BOND FUNDS            
                   Foreign Bond Fund                  
                                                                                
                   STOCK AND BOND FUNDS                                        
                   Strategic Balanced Fund            
                                                                               
                   STOCK FUNDS                        
                   StocksPLUS Fund                     
                   
                   
                   
                              
                                                                                
                                                                                
                                             [LOGO OF PIMCO FUNDS APPEARS HERE] 
<PAGE>
 
            PIMCO Funds: Pacific Investment Management Series
            Prospectus
            April 8, 1998
 
            PIMCO Funds: Pacific Investment Management Series (the "Trust") is
            an open-end series management investment company offering ten sep-
            arate investment portfolios (each a "Fund") in this prospectus.
            The Trust is designed to provide access to the professional in-
            vestment management services offered by Pacific Investment Manage-
            ment Company ("Pacific Investment Management"), which serves as
            investment advisor (the "Advisor") to the Funds. The address of
            PIMCO Funds is 840 Newport Center Drive, Suite 360, Newport Beach,
            CA 92660.
 
            Each Fund offers Class D shares in this Prospectus. Through sepa-
            rate prospectuses, certain Funds and other series of the Trust of-
            fer up to five additional classes of shares, Institutional Class,
            Administrative Class, Class A, Class B and Class C shares. See
            "Description of the Trust--Multiple Classes of Shares."
 
            This Prospectus concisely describes the information investors
            should know before investing in Class D shares of the Funds.
            Please read this Prospectus carefully and keep it for further ref-
            erence. Information about the investment objective of each Fund,
            along with a detailed description of the types of securities in
            which each Fund may invest and of investment policies and restric-
            tions applicable to each Fund, are set forth in this Prospectus.
            There can be no assurance that the investment objective of any
            Fund will be achieved. Because the market value of each Fund's in-
            vestments will change, the investment returns and net asset value
            per share of each Fund will vary.
 
            Class D shares are offered only through financial service firms,
            such as broker-dealers or registered investment advisers, with
            which the Funds' distributor has an agreement for the use of the
            Funds in particular investment products, programs or accounts for
            which a fee may be charged. See "How to Buy Shares." If you wish
            to purchase shares directly from the Trust or the Funds' distribu-
            tor, please consider one of the other classes of shares. See "De-
            scription of the Trust--Multiple Classes of Shares."
 
            A Statement of Additional Information, dated April 1, 1998, as
            amended or supplemented from time to time, is available free of
            charge by writing to PIMCO Funds Distributors LLC (the "Distribu-
            tor"), 2187 Atlantic Street, Stamford, Connecticut 06902, or by
            telephoning 888-87-PIMCO. The Statement of Additional Information,
            which contains more detailed information about the Trust, has been
            filed with the Securities and Exchange Commission and is incorpo-
            rated by reference into this Prospectus. The Securities and Ex-
            change Commission maintains an Internet World Wide Web site (at
            http://www.sec.gov) which contains the Statement of Additional In-
            formation, materials that are incorporated by reference into this
            Prospectus and the Statement of Additional Information, and other
            information about the Funds.
 
            THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SE-
            CURITIES AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMIS-
            SION, NOR HAS THE SECURITIES AND EXCHANGE COMMISSION OR ANY STATE
            SECURITIES COMMISSION PASSED UPON THE ACCURACY OR ADEQUACY OF THIS
            PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OF-
            FENSE.
 
            SHARES OF THE FUNDS ARE NOT DEPOSITS OR OBLIGATIONS OF, OR GUARAN-
            TEED OR ENDORSED BY, ANY FINANCIAL INSTITUTION, AND THE SHARES ARE
            NOT FEDERALLY INSURED BY THE FEDERAL DEPOSIT INSURANCE CORPORA-
            TION, THE FEDERAL RESERVE BOARD OR ANY OTHER AGENCY AND ENTAIL
            RISK, INCLUDING THE POSSIBLE LOSS OF PRINCIPAL.
 
            EACH OF THE FUNDS, EXCEPT THE MUNICIPAL BOND FUND, MAY INVEST ALL
            OF ITS ASSETS IN DERIVATIVE INSTRUMENTS, SOME OF WHICH MAY BE PAR-
            TICULARLY SENSITIVE TO CHANGES IN PREVAILING INTEREST RATES. UNEX-
            PECTED CHANGES IN INTEREST RATES MAY ADVERSELY AFFECT THE VALUE OF
            A FUND'S INVESTMENTS IN PARTICULAR DERIVATIVE INSTRUMENTS.
 
            THE HIGH YIELD FUND MAY INVEST ALL OF ITS ASSETS IN JUNK BONDS,
            WHICH ARE SUBJECT TO HIGH RISK, AND SPECULATIVE WITH REGARD TO
            PAYMENT OF INTEREST AND RETURN OF PRINCIPAL. INVESTORS SHOULD
            CAREFULLY CONSIDER THESE RISKS BEFORE INVESTING IN THE HIGH YIELD
            FUND. SEE "CHARACTERISTICS AND RISKS OF SECURITIES AND INVESTMENT
            TECHNIQUES--HIGH YIELD SECURITIES ("JUNK BONDS")."
 
 
              TABLE OF CONTENTS
 
<TABLE>
<S>                                            <C>
           Distributor.......................  29
           How Net Asset Value Is Determined.  29
           Distributions.....................  30
           Taxes.............................  30
           Management of the Trust...........  32
           Description of the Trust..........  35
           Appendix A--Description of
            Duration.........................  36
           Appendix B--Description of
            Securities Ratings...............  37
           PIMCO Funds Overview..............   3
           Schedule of Fees..................   4
           Investment Objectives and
           Policies..........................   5
           Investment Risks and
           Considerations....................  10
           Characteristics and Risks of
            Securities and Investment
            Techniques.......................  11
           Performance Information...........  26
           How to Buy Shares.................  27
           Exchange Privilege................  28
           How to Redeem.....................  29
</TABLE>

2   PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
            PIMCO Funds Overview

            Pacific Investment Management, a subsidiary of PIMCO Advisors
            L.P., is the investment advisor of all of the Funds. Pacific In-
            vestment Management is one of the premier fixed income investment
            management firms in the U.S. As of December 31, 1997, Pacific In-
            vestment Management had over $118 billion in assets under manage-
            ment. Pacific Investment Management invests in all sectors of the
            fixed income market, using its total return philosophy--seeking
            capital appreciation as well as yield.
 
<TABLE>
<CAPTION>
                            PIMCO                 PRIMARY
                            FUND NAME             OBJECTIVE                              DURATION              CREDIT QUALITY(/1/)
           ------------------------------------------------------------------------------------------------------------------
<S>                                              <C>                                    <C>                   <C>
FUND       SHORT-TERM BOND  Short-Term            Maximum current income, consistent     0-1 year              B to Aaa; max
PROFILES    FUNDS                                 with preservation of capital and                             10% below Baa
                                                  daily liquidity
                            -------------------------------------------------------------------------------------------------
                            Low Duration          Maximum total return, consistent       1-3 years             B to Aaa; max
                                                  with preservation of capital                                 10% below Baa
                                                  and prudent investment management
           ------------------------------------------------------------------------------------------------------------------
           
           INTERMEDIATE-    Real Return Bond      Maximum real return, consistent        Not applicable,       A to Aaa
            TERM                                  with preservation of real capital      but see Fund
            BOND FUNDS                            and prudent investment management      description
                            -------------------------------------------------------------------------------------------------
                            Total Return          Maximum total return, consistent       3-6 years             B to Aaa; max
                                                  with preservation of capital                                 10% below Baa
                                                  and prudent investment management
                            -------------------------------------------------------------------------------------------------
                            Total Return Mortgage Maximum total return, consistent       Lehman Mortgage Index Baa to Aaa; 
                                                  with preservation of capital           + or - 1.5 years      max 10% below 
                                                  and prudent investment management                            Aaa
                            -------------------------------------------------------------------------------------------------
                            High Yield            Maximum total return, consistent       2-6 years             B to Aaa; min
                                                  with preservation of capital                                 65% below Baa
                                                  and prudent investment management
           ------------------------------------------------------------------------------------------------------------------
           
           LONG-TERM BOND   Municipal Bond        High current income exempt from        3-10 years            Ba to Aaa; max
            FUNDS                                 federal income tax, consistent with                          10% below Baa
                                                  preservation of capital
           ------------------------------------------------------------------------------------------------------------------

           INTERNATIONAL    Foreign Bond          Maximum total return, consistent       3-6 years             B to Aaa; max
           BOND FUNDS                             with preservation of capital                                 10% below Baa
                                                  and prudent investment management
                                                  (non-U.S.)
           ------------------------------------------------------------------------------------------------------------------
           STOCK AND BOND
            FUNDS           Strategic Balanced    Maximum total return, consistent       0-6 years             B to Aaa; max
                                                  with preservation of capital                                 10% below Baa
           ------------------------------------------------------------------------------------------------------------------

           STOCK FUNDS      StocksPLUS(/2/)       Total return which exceeds that of the 0-1 year              B to Aaa; max
                                                  S&P 500                                                      10% below Baa
</TABLE>
            1. As rated by Moody's Investors Service, Inc., or if unrated, de-
            termined to be of comparable quality. For specific information
            concerning the credit quality of the securities in each Fund's
            portfolio, see "Investment Objectives and Policies."
            2. The StocksPLUS Fund may invest all of its assets in stock index
            futures backed by short-term bonds.
                                                                               
                                                    April 8, 1998 Prospectus 3
<PAGE>
 
            Schedule of Fees
 
 
<TABLE>
<CAPTION>

SHARE-     ALL FUNDS-CLASS D SHARES
HOLDER     ---------------------------------------------------------------
TRANS-     <S>                                                        <C>
ACTION     MAXIMUM INITIAL SALES CHARGE IMPOSED ON PURCHASES
EXPENSES   (as a percentage of offering price at time of purchase)    None
           ---------------------------------------------------------------
           MAXIMUM SALES CHARGE IMPOSED ON REINVESTED DIVIDENDS
            (as a percentage of net asset value at time of purchase)  None
           ---------------------------------------------------------------
           MAXIMUM DEFERRED SALES CHARGE
            (as a percentage of original purchase price)              None
           ---------------------------------------------------------------
           EXCHANGE FEE                                               None
</TABLE>
 
<TABLE>
<CAPTION>

                                                                            EXAMPLE: You would pay the 
                                                                            following expenses on a
                                                                            $1,000 investment assuming
                                                                            (1) 5% annual return and (2)
                                  ANNUAL FUND OPERATING EXPENSES            redemption at the end of
                                  (As a percentage of average net assets):  each time period:
                                                                 TOTAL
                                            ADMINIS-  12B-1      FUND
                                  ADVISORY  TRATIVE   (SERVICE)  OPERATING  YEAR
           FUND                   FEE       FEE(1)    FEE(1)     EXPENSES   1      3     5     10
           ---------------------------------------------------------------------------------------------
           <S>                    <C>       <C>       <C>        <C>        <C>    <C>   <C>   <C>
           SHORT-TERM             .25%      .25%      .25%        .75%        $ 8  $24   $42   $ 93
           ---------------------------------------------------------------------------------------------
           LOW DURATION           .25       .25       .25         .75           8   24    42     93
           ---------------------------------------------------------------------------------------------
           REAL RETURN BOND       .25       .40       .25         .90           9   29    50    111
           ---------------------------------------------------------------------------------------------
           TOTAL RETURN           .25       .25       .25         .75           8   24    42     93
           ---------------------------------------------------------------------------------------------
           TOTAL RETURN MORTGAGE  .25       .40       .25         .90           9   29    50    111
           ---------------------------------------------------------------------------------------------
           HIGH YIELD             .25       .40       .25         .90           9   29    50    111
           ---------------------------------------------------------------------------------------------
           MUNICIPAL BOND         .25       .35       .25         .85           9   27    47    105
           ---------------------------------------------------------------------------------------------
           FOREIGN BOND           .25       .45       .25         .95          10   30    53    117
           ---------------------------------------------------------------------------------------------
           STRATEGIC BALANCED     .40       .40       .25        1.05          11   33    58    128
           ---------------------------------------------------------------------------------------------
           STOCKSPLUS             .40       .40       .25        1.05          11   33    58    128
           ---------------------------------------------------------------------------------------------
</TABLE>
 
 
 
            1. The Funds' administration agreement includes a plan for Class D
            shares that has been adopted in conformity with the requirements
            set forth in Rule 12b-1 of the Investment Company Act of 1940. The
            plan provides that up to .25% per annum of the total fees paid un-
            der the administration agreement may represent reimbursement for
            expenses in respect of activities ("subject activities") that may
            be deemed to be primarily intended to result in the sale of Class
            D shares. The Short-Term, Low Duration and Total Return Funds will
            pay a total of .50% per annum, the Municipal Bond Fund will pay a
            total of .60% per annum, the Foreign Bond Fund will pay a total of
            .70% per annum, and each remaining Fund will pay a total of .65%
            per annum, under the administration agreement regardless of
            whether a portion or none of the .25% authorized under the plan is
            paid for subject services. To the extent that any payments are
            deemed to be made pursuant to the plan, the Funds intend to treat
            such payments as "service fees" for purposes of applicable rules
            of the National Association of Securities Dealers, Inc. (the
            "NASD"). See "Management of the Trust--Fund Administrator." To the
            extent that such payments for subject activities are deemed not to
            be "service fees," Class D shareholders may, depending on the
            length of time the shares are held, pay more than the economic
            equivalent of the maximum front-end sales charges permitted by
            relevant rules of the NASD.
            The purpose of the foregoing tables is to assist investors in un-
            derstanding the various costs and expenses of the Trust that are
            borne directly or indirectly by Class D shareholders of the Funds.
            The information is based upon each Fund's current fees and ex-
            penses.
 
            NOTE: THE FIGURES SHOWN IN THE EXAMPLE ARE ENTIRELY HYPOTHETICAL.
            THEY ARE NOT REPRESENTATIONS OF PAST OR FUTURE PERFORMANCE OR EX-
            PENSES; ACTUAL PERFORMANCE AND/OR EXPENSES MAY BE MORE OR LESS
            THAN SHOWN.
 
4  PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
            Investment Objectives and Policies

            The investment objective and general investment policies of each
            Fund are described below. There can be no assurance that the in-
            vestment objective of any Fund will be achieved. For temporary,
            defensive or emergency purposes, a Fund may invest without limit
            in U.S. debt securities, including short-term money market securi-
            ties, when in the opinion of the Advisor it is appropriate to do
            so. It is impossible to predict for how long such alternative
            strategies will be utilized. The value of all securities and other
            instruments held by the Funds will vary from time to time in re-
            sponse to a wide variety of market factors. Consequently, the net
            asset value per share of each Fund will vary.
               The investment objective of each Fund is fundamental and may
            not be changed without shareholder approval by vote of a majority
            of the outstanding shares of that Fund. If there is a change in a
            Fund's investment objective, including a change approved by a
            shareholder vote, shareholders should consider whether the Fund
            remains an appropriate investment in light of their then current
            financial position and needs.
               Specific portfolio securities eligible for purchase by the
            Funds, investment techniques that may be used by the Funds, and
            the risks associated with these securities and techniques are de-
            scribed more fully under "Characteristics and Risks of Securities
            and Investment Techniques" in this Prospectus and "Investment Ob-
            jectives and Policies" in the Statement of Additional Information.
 
 
FIXED       With the exception of the Strategic Balanced and StocksPLUS Funds,
INCOME FUND each remaining Fund (together, the "Fixed Income Funds") differs
DESCRIP-    from the others primarily in the length of the Fund's duration or
TIONS       the proportion of its investments in certain types of fixed income
            securities. For a discussion of the concept of duration, see "Ap-
            pendix A--Description of Duration."
               The investment objective of the Short-Term Fund is to seek to
            obtain maximum current income consistent with preservation of cap-
            ital and daily liquidity. The investment objective of the Real Re-
            turn Bond Fund is to seek to realize maximum real return, consis-
            tent with the preservation of real capital and prudent investment
            management. For a discussion of "real return," see "Total Return
            and Real Return," below. The investment objective of the Municipal
            Bond Fund is to seek high current income exempt from federal in-
            come tax, consistent with preservation of capital. Capital appre-
            ciation is a secondary objective of the Municipal Bond Fund. Each
            of the remaining Fixed Income Funds and the Strategic Balanced
            Fund seek to maximize total return, consistent with preservation
            of capital and prudent investment management.
               In selecting securities for each Fixed Income Fund, the Advisor
            utilizes economic forecasting, interest rate anticipation, credit
            and call risk analysis, foreign currency exchange rate forecast-
            ing, and other security selection techniques. The proportion of
            each Fund's assets committed to investment in securities with par-
            ticular characteristics (such as maturity, type and coupon rate)
            will vary based on the Advisor's outlook for the U.S. and foreign
            economies, the financial markets, and other factors.
               Each of the Fixed Income Funds will invest at least 65% of its
            assets in the following types of securities, which, unless specif-
            ically provided otherwise in the descriptions of the Funds that
            follow, may be issued by domestic or foreign entities and denomi-
            nated in U.S. dollars or foreign currencies: securities issued or
            guaranteed by the U.S. Government, its agencies or instrumentali-
            ties ("U.S. Government securities"); corporate debt securities,
            including convertible securities and corporate commercial paper;
            mortgage-backed and other asset-backed securities; inflation-in-
            dexed bonds issued by both governments and corporations; struc-
            tured notes, including hybrid or "indexed" securities, and loan
            participations; delayed funding loans and revolving credit facili-
            ties; bank certificates of deposit, fixed time deposits and bank-
            ers' acceptances; repurchase agreements and reverse repurchase
            agreements; debt securities issued by states or local governments
            and their agencies, authorities and other instrumentalities; obli-
            gations of foreign governments or their subdivisions, agencies and
            instrumentalities; and obligations of international agencies or
            supranational entities. Fixed income securities may have fixed,
            variable, or floating rates of interest, including rates of inter-
            est that vary inversely at a multiple of a designated or floating
            rate, or that vary according to changes in relative values of cur-
            rencies. Each of the Fixed Income Funds may hold different per-
            centages of its assets in these various types of securities, and
            each Fund may invest all of its assets in derivative instruments
            or in mortgage- or asset-backed securities. Each of the Fixed In-
            come

                                                    April 8, 1998 Prospectus 5
<PAGE>
 
            Funds may adhere to its investment policy by entering into a se-
            ries of purchase and sale contracts or utilizing other investment
            techniques by which it may obtain market exposure to the securi-
            ties in which it primarily invests.
               In addition, each of the Fixed Income Funds may lend its port-
            folio securities to brokers, dealers and other financial institu-
            tions in order to earn income. Each of the Fixed Income Funds may
            purchase and sell options and futures subject to the limits dis-
            cussed below, engage in credit spread trades and enter into for-
            ward foreign currency contracts.
               The Real Return Bond and Foreign Bond Funds will normally in-
            vest at least 80% of its total assets in "bonds." For this pur-
            pose, each of these Funds considers the various types of debt or
            fixed income securities in which it invests, as specifically de-
            scribed elsewhere in this Prospectus, to be "bonds" as referenced
            in that Fund's name. The use of this name is not meant to restrict
            a Fund's investment to the narrow category of debt securities that
            are formally called "bonds."
               As a non-fundamental, operating policy, the Advisor intends to
            use foreign currency-related derivative instruments (currency
            futures and related options, currency options, forward contracts
            and swap agreements) in an effort to hedge foreign currency risk
            with respect to at least 75% of the assets of the Fixed Income
            Funds denominated in currencies other than the U.S. dollar. There
            can be no assurance that the Advisor will be successful in doing
            so. The active use of currency derivatives involves transaction
            costs which may adversely effect yield and return.
 
            The compositions of the Fixed Income Funds differ as follows:
 
            SHORT-TERM FUND invests in a diversified portfolio of fixed income
            securities of varying maturities. The average portfolio duration
            of this Fund will normally not exceed one year. The Fund may in-
            vest up to 10% of its assets in fixed income securities that are
            rated below investment grade (rated below Baa by Moody's Investors
            Service, Inc. ("Moody's") or BBB by Standard & Poor's Ratings
            Services ("S&P")) but rated B or higher by Moody's or S&P (or, if
            unrated, determined by the Advisor to be of comparable quality).
            For information on the risks associated with investments in secu-
            rities rated below investment grade, see "Appendix B--Description
            of Securities Ratings." The Fund may invest up to 5% of its assets
            in securities denominated in foreign currencies, and may invest
            beyond this limit in U.S. dollar-denominated securities of foreign
            issuers.
 
            LOW DURATION FUND invests in a diversified portfolio of fixed in-
            come securities of varying maturities. The average portfolio dura-
            tion of this Fund will normally vary within a one- to three-year
            time frame based on the Advisor's forecast for interest rates. The
            Fund may invest up to 10% of its assets in fixed income securities
            that are rated below investment grade but rated B or higher by
            Moody's or S&P (or, if unrated, determined by the Advisor to be of
            comparable quality). For information on the risks associated with
            investments in securities rated below investment grade, see "Ap-
            pendix B--Description of Securities Ratings." The Fund may invest
            up to 20% of its assets in securities denominated in foreign cur-
            rencies, and may invest beyond this limit in U.S. dollar-denomi-
            nated securities of foreign issuers.
            The total rate of return for this Fund is expected to exhibit less
            volatility than that of the Total Return Fund because its duration
            will be shorter.
 
            REAL RETURN BOND FUND invests under normal circumstances at least
            65% of its total assets in inflation-indexed bonds issued by U.S.
            and foreign governments, their agencies or instrumentalities. All
            securities purchased by the Fund must be rated at least A by
            Moody's or S&P (or, if unrated, determined by the Advisor to be of
            comparable quality), and the Fund will maintain a minimum average
            quality of Aa. The Fund may invest up to 35% of its assets in
            other types of fixed income instruments, including securities de-
            nominated in foreign currencies (and the Fund may also invest be-
            yond this limit in U.S. dollar-denominated securities of foreign
            issuers).
               Inflation-indexed bonds are fixed income securities whose prin-
            cipal value is periodically adjusted according to the rate of in-
            flation. Such bonds generally are issued at an interest rate lower
            than non-inflation related bonds, but are
 
6 PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
            expected to retain their value against inflation over time. For a
            more complete discussion of inflation-indexed bonds, including the
            risks associated with investing in such securities, see "Charac-
            teristics and Risks of Securities and Investment Techniques--In-
            flation-Indexed Bonds." See "Taxes" for information about the pos-
            sible tax consequences of investing in the Fund and in inflation-
            indexed bonds.
               In managing fixed income securities, one of the principal tools
            generally used by the Advisor is "duration," which is a measure of
            the expected life of a fixed income security on a present value
            basis, incorporating a bond's yield, coupon interest payments, fi-
            nal maturity and call features. See "Appendix A--Description of
            Duration." Because of the unique features of inflation-indexed
            bonds, the Advisor utilizes a modified form of duration for the
            Real Return Bond Fund ("modified real duration") which measures
            price changes in such bonds as a result of changes in real, rather
            than nominal, interest rates. Although there is no limit on the
            modified real duration of the Real Return Bond Fund, it is ex-
            pected that the average modified real duration of the Fund will
            normally vary approximately with the range of the average modified
            real duration of all inflation-indexed bonds issued by the U.S.
            Treasury in the aggregate.
 
            TOTAL RETURN FUND invests under normal circumstances at least 65%
            of its assets in a diversified portfolio of fixed income securi-
            ties of varying maturities. The average portfolio duration of this
            Fund will normally vary within a three- to six-year time frame
            based on the Advisor's forecast for interest rates. The Fund may
            invest up to 10% of its assets in fixed income securities that are
            rated below investment grade but rated B or higher by Moody's or
            S&P (or, if unrated, determined by the Advisor to be of comparable
            quality). For information on the risks associated with investments
            in securities rated below investment grade, see "Appendix B--De-
            scription of Securities Ratings." The Fund may also invest up to
            20% of its assets in securities denominated in foreign currencies,
            and may invest beyond this limit in U.S. dollar-denominated secu-
            rities of foreign issuers. Portfolio holdings will be concentrated
            in areas of the bond market (based on quality, sector, coupon or
            maturity) which the Advisor believes to be relatively undervalued.
            The total rate of return for this Fund is expected to exhibit less
            volatility than that of the Long-Term U.S. Government Fund because
            its duration will normally be shorter.
 
            TOTAL RETURN MORTGAGE FUND invests under normal circumstances at
            least 80% of its assets in a diversified portfolio of mortgage-re-
            lated securities. The Fund will not acquire a security if, as a
            result, more than 10% of the Fund's total assets would be invested
            in securities rated below Aaa by Moody's of AAA by S&P, subject to
            a minimum rating of Baa by Moody's or BBB by S&P (or, if unrated,
            determined by the Advisor to be of comparable quality). The aver-
            age portfolio duration of this Fund will normally vary approxi-
            mately within a range of plus or minus one and one-half years of
            the average duration of the Lehman Brothers Mortgage-Backed Secu-
            rities Index, which, as of May 31, 1997, had an average duration
            of approximately four years.
 
            HIGH YIELD FUND invests under normal circumstances at least 65% of
            its assets in a diversified portfolio of fixed income securities
            rated lower than Baa by Moody's or lower than BBB by S&P but rated
            at least B by Moody's or S&P (or, if unrated, determined by the
            Advisor to be of comparable quality). The remainder of the Fund's
            assets may be invested in investment grade fixed income securities
            (i.e., securities rated at least Baa by Moody's or BBB by S&P, or,
            if unrated, deemed by the Advisor to be of comparable quality).
            The average portfolio duration of this Fund will normally vary
            within a two- to six-year time frame depending on the Advisor's
            view of the potential for total return offered by a particular du-
            ration strategy. The Fund may invest in securities of foreign is-
            suers, but only those that are U.S. dollar-denominated. The Fund
            may also engage in hedging strategies involving equity options.
               Investments in high yield securities, while generally providing
            greater potential opportunity for capital appreciation and higher
            yields than investments in higher rated securities, also entail
            greater risk, including the possibility of default or bankruptcy
            of the issuer of such securities. Risk of default or bankruptcy
            may be greater in periods of economic uncertainty or recession, as
            the issuers of high yield securities may be less able to withstand
            general economic

                                                     April 8, 1998 Prospectus 7
<PAGE>
 
            downturns. The Advisor seeks to reduce risk through diversifica-
            tion, credit analysis and attention to current developments and
            trends in both the economy and financial markets. The value of all
            fixed income securities, including those held by the Fund, can be
            expected to change inversely with interest rates. For a further
            discussion of the special risks of investing in lower-rated secu-
            rities, see "Characteristics and Risks of Securities and Invest-
            ment Techniques--High Yield Securities ("Junk Bonds")."
 
            MUNICIPAL BOND FUND seeks high current income exempt from federal
            income tax, consistent with preservation of capital. Capital ap-
            preciation is a secondary objective. The Fund seeks its objectives
            by investing in debt securities whose interest is, in the opinion
            of bond counsel for the issuer at the time of issuance, exempt
            from federal income tax ("Municipal Bonds"). Municipal Bonds gen-
            erally are issued by states and local governments and their agen-
            cies, authorities and other instrumentalities. It is a policy of
            the Fund that, under normal market conditions, at least 80% of its
            net assets will be invested in Municipal Bonds. The Fund may in-
            vest up to 20% of its net assets in U.S. Government securities,
            money market instruments and/or "private activity" bonds. Under
            normal circumstances, the average portfolio duration of the Munic-
            ipal Bond Fund will vary within a three- to ten-year time frame,
            based on the Advisor's forecast for interest rates.
 
               The Fund may invest up to 10% of its net assets in Municipal
            Bonds or "private activity" bonds which are rated below Baa by
            Moody's or BBB by S&P but which are rated at least Ba by Moody's
            or BB by S&P (or, if unrated, determined by the Advisor to be of
            comparable quality). For information on the risks associated with
            investments in securities rated below investment grade, see "Ap-
            pendix B--Description of Securities Ratings."
 
            FOREIGN BOND FUND invests in a portfolio of fixed income securi-
            ties primarily denominated in major foreign currencies and baskets
            of foreign currencies (such as the European Currency Unit, or
            "ECU"). The Advisor will invest the assets of the Fund in a number
            of international bond markets so that, under normal circumstances,
            the Fund will invest at least 85% of its assets in securities of
            issuers located outside the United States, representing at least
            three foreign countries, which may be represented by futures con-
            tracts (including related options) with respect to such securi-
            ties, and options on such securities, when the Advisor deems it
            appropriate to do so. The Fund may invest up to 10% of its assets
            in fixed income securities that are rated below investment grade
            but rated B or higher by Moody's or S&P (or, if unrated, deter-
            mined by the Advisor to be of comparable quality). Securities
            rated below investment grade may be referred to colloquially as
            "junk bonds." For information on the risks associated with invest-
            ments in securities rated below investment grade, see "Appendix
            B--Description of Securities Ratings." The average portfolio dura-
            tion of this Fund will normally vary within a three- to six-year
            time frame.
 
 
STOCK AND   STRATEGIC BALANCED FUND has as its investment objective the maxi-
BOND FUND   mization of total return, consistent with preservation of capital
DESCRIPTION and prudent investment management. In seeking to achieve this ob-
            jective, the Fund invests in the securities eligible for purchase
            by the StocksPLUS Fund and the Total Return Fund. The percentage
            of the Fund's assets allocated to equity or fixed income exposure
            will vary in accordance with an asset allocation methodology de-
            veloped by the Advisor. The methodology builds upon the Advisor's
            long-standing process of economic forecasting of business cycle
            stages by applying to this process a disciplined asset allocation
            model which employs certain statistical variance techniques. De-
            pending on the outcome of this asset allocation methodology, the
            Fund's equity exposure will vary between 45% and 75% of its total
            assets, and its fixed income exposure will vary between 25% and
            55%. There can be no assurance that the Advisor's asset allocation
            methodology will be successful.
 
 
STOCK FUND  STOCKSPLUS FUND, as its investment objective, seeks to achieve to- 
DESCRIPTION tal return which exceeds the total return performance of the Stan- 
            dard & Poor's 500 Composite Stock Price Index ("S&P 500").         
            StocksPLUS is the name of a proprietary portfolio management       
            strategy which utilizes S&P 500 derivatives in addition to or in   
            place of S&P 500 stocks to equal                                    
            
8 PIMCO Funds: Pacific Investment Management Series

<PAGE>
 
            or exceed the performance of the S&P 500. The Advisor expects that
            under normal market conditions, the Fund will invest substantially
            all of its assets in S&P 500 derivatives, backed by a portfolio of
            fixed income securities. The Advisor will actively manage the
            fixed income assets serving as cover for derivatives, as well as
            any other fixed income assets held by the Fund, with a view toward
            enhancing the Fund's total return investment performance, subject
            to an overall portfolio duration which is normally not expected to
            exceed one year. See "Appendix A--Description of Duration."
               The S&P 500 is composed of 500 selected common stocks, most of
            which are listed on the New York Stock Exchange. S&P chooses the
            stocks to be included in the S&P 500 solely on a statistical ba-
            sis. The weightings of stocks in the index are based on each
            stock's relative total market value, that is, its market price per
            share times the number of shares outstanding. Stocks represented
            currently in the S&P 500 represent approximately two-thirds of the
            total market value of all U.S. common stocks. The Fund is neither
            sponsored by nor affiliated with S&P. The Fund will seek to remain
            invested in S&P 500 derivatives or S&P 500 stocks even when the
            S&P 500 is declining.
               When S&P 500 derivatives appear to be overvalued relative to
            the S&P 500, the Fund may invest up to 100% of its assets in a
            "basket" of S&P 500 stocks. The composition of this basket will be
            determined by standard statistical techniques that analyze the
            historical correlation between the return of every stock currently
            in the S&P 500 and the return on the S&P 500 itself. The Advisor
            may employ fundamental stock analysis only to choose among stocks
            that have already satisfied the statistical correlation tests.
            Stocks chosen for the Fund are not limited to those with any par-
            ticular weighting in the S&P 500.
               Positions in S&P 500 futures and options on futures will be en-
            tered into only to the extent they constitute permissible posi-
            tions for the Fund according to applicable rules of the Commodity
            Futures Trading Commission ("CFTC"). From time to time, the Advi-
            sor may be constrained in its ability to use S&P 500 derivatives
            either by requirements of the Internal Revenue Code or by an unan-
            ticipated inability to close out positions when it would be most
            advantageous to do so. A large number of investors use S&P 500 de-
            rivatives for both hedging and speculative purposes, and although
            generally this helps guarantee a liquid market in those instru-
            ments, at times liquidity may be
            limited. For more information about S&P 500 derivatives, see
            "Characteristics and Risks of Securities and Investment Tech-
            niques--Derivative Instruments."
               Assets of the StocksPLUS Fund not invested in equity securities
            may be invested in securities eligible for purchase by the Fixed
            Income Funds. The Fund may invest up to 10% of its assets in fixed
            income securities that are below "investment grade," i.e., rated
            below Baa by Moody's or BBB by S&P, but at least B (or, if
            unrated, determined by the Advisor to be of comparable quality).
            In addition, the StocksPLUS Fund may lend its portfolio securities
            to brokers, dealers and other financial institutions in order to
            earn income. The Fund may also invest all of its assets in deriva-
            tive instruments, as described under "Characteristics of Securi-
            ties and Investment Techniques--Derivative Instruments." In addi-
            tion, the Fund may invest up to 20% of its assets in securities of
            foreign issuers, may purchase and sell options and futures on for-
            eign currencies, and may enter into forward foreign currency con-
            tracts.
 
 
TOTAL       The "total return" sought by certain of the Funds will consist of
RETURN AND  interest and dividends from underlying securities, capital appre-
REAL RETURN ciation reflected in unrealized increases in value of portfolio
            securities (realized by the shareholder only upon selling shares),
            or realized from the purchase and sale of securities and use of
            futures and options, or gains from favorable changes in foreign
            currency exchange rates. Generally, over the long term, the total
            return obtained by a portfolio investing primarily in fixed income
            securities is not expected to be as great as that obtained by a
            portfolio that invests primarily in equity securities. At the same
            time, the market risk and price volatility of a fixed income port-
            folio is expected to be less than that of an equity portfolio, so
            that a fixed income portfolio is generally considered to be a more
            conservative investment. The change in market value of fixed in-
            come securities (and therefore their capital appreciation or de-
            preciation) is largely a function of changes in the current level
            of interest rates. Generally, when interest rates are falling, a
            portfolio with a shorter duration will not generate as high a
            level of total return as a portfolio with a longer duration. Con-
            versely, when interest rates are rising, a portfolio with a
            shorter duration will generally outperform longer duration portfo-
            lios. When interest rates are flat, shorter duration portfolios
            generally will not generate as high a

                                                    April 8, 1998 Prospectus 9
                                                                              
<PAGE>
 
            level of total return as longer duration portfolios (assuming that
            long-term interest rates are higher than short-term rates, which
            is commonly the case). With respect to the composition of any
            fixed income portfolio, the longer the duration of the portfolio,
            the greater the anticipated potential for total return, with, how-
            ever, greater attendant market risk and price volatility than for
            a portfolio with a shorter duration. The market value of fixed in-
            come securities denominated in currencies other than the U.S. dol-
            lar also may be affected by movements in foreign currency ex-
            change rates.
               The change in market value of equity securities (and therefore
            their capital appreciation or depreciation) may depend upon a num-
            ber of factors, including: conditions in the securities markets,
            the business success of the security's issuer, changing interest
            rates, real or perceived economic and competitive industry condi-
            tions, and foreign currency exchange rates. Historically, the to-
            tal return performance of equity-oriented portfolios has generally
            been greater over the long term than fixed income portfolios. How-
            ever, the market risk and price volatility of an equity portfolio
            is generally greater than that of a fixed income portfolio, and is
            generally considered to be a more aggressive investment.
               "Real Return," or "Inflation Adjusted Return," as referenced in
            the name and investment objective of the Real Return Bond Fund, is
            a measure of the change in purchasing power of money invested in a
            particular instrument after adjusting for inflation. An investment
            in a security generating a high nominal return (such as a typical
            U.S. Government Treasury bond) may not generate a high real return
            once inflation is considered. For example, an instrument generat-
            ing a 9% nominal return at a time when inflation is 6% has a real
            return of approximately 3%; that is, the purchasing power of the
            money invested in that instrument would only increase by approxi-
            mately 3%. On the other hand, an inflation-indexed instrument gen-
            erating a 5% real return would generate a 5% increase in purchas-
            ing power regardless of the rate of inflation. As stated above,
            the investment objective of the Fund is to seek to achieve maximum
            real return. The total return (not adjusted for inflation) at-
            tained by this Fund may be less than the total return attained by
            other of the Funds that do not invest primarily in inflation-in-
            dexed securities.
               In the case of inflation-indexed bonds, changes in market value
            are tied to the relationship between nominal interest rates and
            the rate of inflation. If inflation were to rise at a faster rate
            than nominal interest rates, real interest rates might decline,
            leading to an increase in value of inflation-indexed bonds. In
            contrast, if nominal interest rates increase at a faster rate than
            inflation, real interest rates might increase, leading to a de-
            crease in value of inflation-indexed bonds.
 
            Investment Risks and Considerations
 
            The following are some of the principal risks of investing in the
            Funds. Investors should read this Prospectus carefully for a more
            complete discussion of the risks relating to an investment in the
            Funds. The net asset value per share of any Fund may be less at
            the time of redemption than it was at the time of investment. Gen-
            erally, the value of fixed income securities can be expected to
            vary inversely with changes in prevailing interest rates, i.e., as
            interest rates rise, market value tends to decrease, and vice
            versa, although this may not be true in the case of inflation-
            indexed bonds. In addition, certain of the Funds may invest in se-
            curities rated lower than Baa by Moody's or S&P. Such securities
            carry a high degree of credit risk and are considered speculative
            by the major rating agencies.
               Certain Funds may invest in securities of foreign issuers,
            which may be subject to additional risk factors, including foreign
            currency and political risks, not applicable to securities of U.S.
            issuers. Certain of the Funds' investment techniques may involve a
            form of borrowing, which may tend to exaggerate the effect on net
            asset value of any increase or decrease in the market value of a
            Fund's portfolio and may require liquidation of portfolio posi-
            tions when it is not advantageous to do so. Certain Funds may sell
            securities short, which exposes the Fund to a risk of loss if the
            value of the security sold short should increase.
               All Funds may use derivative instruments, consisting of
            futures, options, options on futures, and swap agreements, for
            hedging purposes or as part of their investment strategies. Use of
            these instruments may involve certain costs and risks, including
            the risk that a Fund could not close out a position when it would
            be most advantageous to do so, the risk
 
10 PIMCO Funds: Pacific Investment Management Series
 
<PAGE>
 
            of an imperfect correlation between the value of the securities
            being hedged and the value of the particular derivative instru-
            ment, and the risk that unexpected changes in interest rates may
            adversely affect the value of a Fund's investments in particular
            derivative instruments. Unless otherwise indicated, all limita-
            tions applicable to Fund investments (as stated in this Prospectus
            and in the Statement of Additional Information) apply only at the
            time a transaction is entered into. Any subsequent change in a
            rating assigned by any rating service to a security (or, if
            unrated, deemed to be of comparable quality), or change in the
            percentage of Fund assets invested in certain securities or other
            instruments, or change in the average duration of a Fund's invest-
            ment portfolio, resulting from market fluctuations or other
            changes in a Fund's total assets, will not require a Fund to dis-
            pose of an investment until the Advisor determines that is practi-
            cable to sell or close out the investment without undue market or
            tax consequences to the Fund. In the event that ratings services
            assign different ratings to the same security, the Advisor will
            determine which rating it believes best reflects the security's
            quality and risk at that time, which may be the higher of the sev-
            eral assigned ratings.
               Investors should carefully consider the possible tax conse-
            quences from investing in the Real Return Bond Fund. The Fund in-
            vests primarily in securities that for tax purposes may be consid-
            ered to have been issued originally at a discount. Accordingly,
            the Fund may be required to make annual distributions to share-
            holders in excess of the cash received by the Fund in a given pe-
            riod from those investments. See "Characteristics and Risks of Se-
            curities and Investment Techniques--Inflation-Indexed Bonds" and
            "Taxes" for additional information.
               The Real Return Bond and Foreign Bond Funds are "non-diversi-
            fied" for purposes of the Investment Company Act of 1940 ("1940
            Act"), meaning that they may invest a greater percentage of their
            assets in the securities of one issuer than the other Funds. The
            Funds are still, however, subject to diversification requirements
            imposed by the Internal Revenue Code of 1986, as amended, which
            means that as of the end of each calendar quarter, a Fund may have
            no more than 25% of its assets invested in the securities of a
            single issuer, and may, with respect to 50% of its assets, have no
            more than 5% of its assets invested in the securities of a single
            issuer. As "non-diversified" portfolios, these Funds may be more
            susceptible to risks associated with a single economic, political
            or regulatory occurrence than a diversified portfolio might be.
               The Funds offer their shares to both retail and institutional
            investors. Institutional shareholders, some of whom also may be
            investment advisory clients of Pacific Investment Management, may
            hold large positions in certain of the Funds. Such shareholders
            may on occasion make large redemptions of their holdings in the
            Funds to meet their liquidity needs, in connection with strategic
            adjustments to their overall portfolio of investments, or for
            other purposes. Large redemptions from some Funds could require
            the Advisor to liquidate portfolio positions when it is not most
            desirable to do so. Liquidation of portfolio holdings also may
            cause a Fund to realize taxable capital gains.
 
            Characteristics and Risks of
            Securities and Investment Techniques
 
            The following describes in greater detail different types of secu-
            rities and investment techniques used by the individual Funds, and
            discusses certain concepts relevant to the investment policies of
            the Funds. Additional information about the Funds' investments and
            investment practices may be found in the Statement of Additional
            Information.
 
 
U.S.
GOVERNMENT  U.S. Government securities are obligations of, or guaranteed by,
SECURITIES  the U.S. Government, its agencies or instrumentalities. The U.S.
            Government does not guarantee the net asset value of the Funds'
            shares. Some U.S. Government securities, such as Treasury bills,
            notes and bonds, and securities guaranteed by the Government Na-
            tional Mortgage Association ("GNMA"), are supported by the full
            faith and credit of the United States; others, such as those of
            the Federal Home Loan Banks, are supported by the right of the is-
            suer to borrow from the U.S. Treasury; others, such as those of
            the Federal National Mortgage Association ("FNMA"), are supported
            by the discretionary authority of the U.S. Government to purchase
            the agency's obligations; and still others, such as those of the
            Student Loan Marketing Association,

                                                  April 8, 1998 Prospectus 11
<PAGE>
 
            are supported only by the credit of the instrumentality. U.S. Gov-
            ernment securities include securities that have no coupons, or
            have been stripped of their unmatured interest coupons, individual
            interest coupons from such securities that trade separately, and
            evidences of receipt of such securities. Such securities may pay
            no cash income, and are purchased at a deep discount from their
            value at maturity. Because interest on zero coupon securities is
            not distributed on a current basis but is, in effect, compounded,
            zero coupon securities tend to be subject to greater market risk
            than interest-paying securities of similar maturities. Custodial
            receipts issued in connection with so-called trademark zero coupon
            securities, such as CATs and TIGRs, are not issued by the U.S.
            Treasury, and are therefore not U.S. Government securities, al-
            though the underlying bond represented by such receipt is a debt
            obligation of the U.S. Treasury. Other zero coupon Treasury secu-
            rities (STRIPs and CUBEs) are direct obligations of the U.S. Gov-
            ernment.
 
 
CORPORATE   Corporate debt securities include corporate bonds, debentures,
DEBT        notes and other similar corporate debt instruments, including con-
SECURITIES  vertible securities. Debt securities may be acquired with warrants
            attached. Corporate income-producing securities may also include
            forms of preferred or preference stock. The rate of interest on a
            corporate debt security may be fixed, floating or variable, and
            may vary inversely with respect to a reference rate. See "Variable
            and Floating Rate Securities" below. The rate of return or return
            of principal on some debt obligations may be linked or indexed to
            the level of exchange rates between the U.S. dollar and a foreign
            currency or currencies.
               Investments in corporate debt securities that are rated below
            investment grade (rated below Baa (Moody's) or BBB (S&P)) are de-
            scribed as "speculative" both by Moody's and S&P. Such securities
            are sometimes referred to as "junk bonds," and may be subject to
            greater market fluctuations, less liquidity and greater risk of
            loss of income or principal, including a greater possibility of
            default or bankruptcy of the issuer of such securities, than are
            more highly rated debt securities. Moody's also describes securi-
            ties rated Baa as having speculative characteristics. The Advisor
            seeks to minimize these risks through diversification, in-depth
            credit analysis and attention to current developments in interest
            rates and market conditions. See "Appendix B--Description of Secu-
            rities Ratings." Investments in high yield securities are dis-
            cussed separately below under "High Yield Securities ("Junk
            Bonds")."
 
 
CONVERTIBLE Each Fund (except the Municipal Bond Fund) may invest in convert-
SECURITIES  ible securities, which may offer higher income than the common
            stocks into which they are convertible. Typically, convertible se-
            curities are callable by the company, which may, in effect, force
            conversion before the holder would otherwise choose.
               The convertible securities in which the Funds may invest con-
            sist of bonds, notes, debentures and preferred stocks which may be
            converted or exchanged at a stated or determinable exchange ratio
            into underlying shares of common stock. A Fund may be required to
            permit the issuer of a convertible security to redeem the securi-
            ty, convert it into the underlying common stock, or sell it to a
            third party. Thus, a Fund may not be able to control whether the
            issuer of a convertible security chooses to convert that security.
            If the issuer chooses to do so, this action could have an adverse
            effect on a Fund's ability to achieve its investment objectives.
               While the Fixed Income Funds intend to invest primarily in
            fixed income securities, each may invest in convertible securities
            or equity securities. While some countries or companies may be re-
            garded as favorable investments, pure fixed income opportunities
            may be unattractive or limited due to insufficient supply, legal
            or technical restrictions. In such cases, a Fund may consider eq-
            uity securities or convertible bonds to gain exposure to such in-
            vestments.
 
 
LOAN        Certain Funds may invest in fixed- and floating-rate loans ar-
PARTICIPA-  ranged through private negotiations between an issuer of debt in-
TIONS AND   struments and one or more financial institutions ("lenders"). Gen-
ASSIGNMENTS erally, the Funds' investments in loans are expected to take the
            form of loan participations and assignments of portions of loans
            from third parties.
               Large loans to corporations or governments may be shared or
            syndicated among several lenders, usually banks. The Funds may
            participate in such syndicates, or can buy part of a loan, becom-
            ing a direct lender. Participations and assignments involve spe-
            cial types of risk, including limited marketability and the risks
            of being a lender. See "Illiquid Securities" for a discussion of
            the limits on a Fund's investments in loan participations and as-
            signments with limited
 
12  PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
            marketability. If a Fund purchases a participation, it may only be
            able to enforce its rights through the lender, and may assume the
            credit risk of the lender in addition to the borrower. In assign-
            ments, the Funds' rights against the borrower may be more limited
            than those held by the original lender.
 
 
DELAYED     The Funds (except the PIMCO Municipal Bond Fund) may also enter
FUNDING     into, or acquire participations in, delayed funding loans and re-
LOANS AND   volving credit facilities. Delayed funding loans and revolving
REVOLVING   credit facilities are borrowing arrangements in which the lender
CREDIT      agrees to make loans up to a maximum amount upon demand by the
FACILITIES  borrower during a specified term. A revolving credit facility dif-
            fers from a delayed funding loan in that as the borrower repays
            the loan, an amount equal to the repayment may be borrowed again
            during the term of the revolving credit facility. These commit-
            ments may have the effect of requiring a Fund to increase its in-
            vestment in a company at a time when it might not otherwise decide
            to do so (including at a time when the company's financial condi-
            tion makes it unlikely that such amounts will be repaid).
               The Funds may acquire a participation interest in delayed fund-
            ing loans or revolving credit facilities from a bank or other fi-
            nancial institution. See "Loan Participations and Assignments."
            The terms of the participation require the Fund to make a pro rata
            share of all loans extended to the borrower and entitles the Fund
            to a pro rata share of all payments made by the borrower. Delayed
            funding loans and revolving credit facilities usually provide for
            floating or variable rates of interest. To the extent that a Fund
            is committed to advance additional funds, it will at all times
            segregate assets, determined to be liquid by the Advisor in accor-
            dance with procedures established by the Board of Trustees, in an
            amount sufficient to meet such commitments.
 
 
 
VARIABLE    Variable and floating rate securities provide for a periodic ad-
AND         justment in the interest rate paid on the obligations. The terms
FLOATING    of such obligations must provide that interest rates are adjusted
RATE        periodically based upon an interest rate adjustment index as pro-
SECURITIES  vided in the respective obligations. The adjustment intervals may
            be regular, and range from daily up to annually, or may be event
            based, such as based on a change in the prime rate.
               Each of the Fixed Income Funds may invest in floating rate debt
            instruments ("floaters") and (except the Municipal Bond Fund) en-
            gage in credit spread trades. The interest rate on a floater is a
            variable rate which is tied to another interest rate, such as a
            money-market index or Treasury bill rate. The interest rate on a
            floater resets periodically, typically every six months. While,
            because of the interest rate reset feature, floaters provide a
            Fund with a certain degree of protection against rises in interest
            rates, a Fund will participate in any declines in interest rates
            as well. A credit spread trade is an investment position relating
            to a difference in the prices or interest rates of two securities
            or currencies, where the value of the investment position is de-
            termined by movements in the difference between the prices or in-
            terest rates, as the case may be, of the respective securities or
            currencies.
               Each of the Fixed Income Funds (except the Municipal Bond Fund)
            may also invest in inverse floating rate debt instruments ("in-
            verse floaters"). The interest rate on an inverse floater resets
            in the opposite direction from the market rate of interest to
            which the inverse floater is indexed. An inverse floating rate se-
            curity may exhibit greater price volatility than a fixed rate ob-
            ligation of similar credit quality. The Funds have adopted a pol-
            icy under which no Fund will invest more than 5% (10% in the case
            of the Total Return Mortgage Fund) of its net assets in any combi-
            nation of inverse floater, interest only ("IO"), or principal only
            ("PO") securities. See "Mortgage-Related and Other Asset-Backed
            Securities" for a discussion of IOs and POs.
 
 

INFLATION-  Inflation-indexed bonds are fixed income securities whose princi-
INDEXED     pal value is periodically adjusted according to the rate of infla-
BONDS       tion. The interest rate on these bonds is generally fixed at issu-
            ance at a rate lower than typical bonds. Over the life of an in-
            flation-indexed bond, however, interest will be paid based on a
            principal value which is adjusted for inflation.
               Inflation-indexed securities issued by the U.S. Treasury will
            initially have maturities of five or ten years, although it is an-
            ticipated that securities with other maturities will be issued in
            the future. The securities will pay interest on a semi-annual ba-
            sis, equal to a fixed percentage of the inflation-adjusted princi-
            pal amount. For example, if an investor

                                                   April 8, 1998 Prospectus 13
<PAGE>
 
            purchased an inflation-indexed bond with a par value of $1,000 and
            a 3% real rate of return coupon (payable 1.5% semi-annually), and
            inflation over the first six months were 1%, the mid-year par
            value of the bond would be $1,010 and the first semi-annual inter-
            est payment would be $15.15 ($1,010 times 1.5%). If inflation dur-
            ing the second half of the year reached 3%, the end-of-year par
            value of the bond would be $1,030 and the second semi-annual in-
            terest payment would be $15.45 ($1,030 times 1.5%).
               If the periodic adjustment rate measuring inflation falls, the
            principal value of inflation-indexed bonds will be adjusted down-
            ward, and consequently the interest payable on these securities
            (calculated with respect to a smaller principal amount) will be
            reduced. Repayment of the original bond principal upon maturity
            (as adjusted for inflation) is guaranteed in the case of U.S.
            Treasury inflation-indexed bonds, even during a period of defla-
            tion. However, the current market value of the bonds is not guar-
            anteed, and will fluctuate. The Funds may also invest in other in-
            flation related bonds which may or may not provide a similar guar-
            antee. If such a guarantee of principal is not provided, the ad-
            justed principal value of the bond repaid at maturity may be less
            than the original principal.
               The value of inflation-indexed bonds is expected to change in
            response to changes in real interest rates. Real interest rates in
            turn are tied to the relationship between nominal interest rates
            and the rate of inflation. Therefore, if inflation were to rise at
            a faster rate than nominal interest rates, real interest rates
            might decline, leading to an increase in value of inflation-in-
            dexed bonds. In contrast, if nominal interest rates increased at a
            faster rate than inflation, real interest rates might rise, lead-
            ing to a decrease in value of inflation-indexed bonds.
               While these securities are expected to be protected from long-
            term inflationary trends, short-term increases in inflation may
            lead to a decline in value. If interest rates rise due to reasons
            other than inflation (for example, due to changes in currency ex-
            change rates), investors in these securities may not be protected
            to the extent that the increase is not reflected in the bond's in-
            flation measure.
               The U.S. Treasury has only recently begun issuing inflation-in-
            dexed bonds. As such, there is no trading history of these securi-
            ties, and there can be no assurance that a liquid market in these
            instruments will develop, although one is expected. Lack of a liq-
            uid market may impose the risk of higher transaction costs and the
            possibility that a Fund may be forced to liquidate positions when
            it would not be advantageous to do so. There also can be no assur-
            ance that the U.S. Treasury will issue any particular amount of
            inflation-indexed bonds. Certain foreign governments, such as the
            United Kingdom, Canada and Australia, have a longer history of is-
            suing inflation-indexed bonds, and there may be a more liquid mar-
            ket in certain of these countries for these securities.
               The periodic adjustment of U.S. inflation-indexed bonds is tied
            to the Consumer Price Index for Urban Consumers ("CPI-U"), which
            is calculated monthly by the U.S. Bureau of Labor Statistics. The
            CPI-U is a measurement of changes in the cost of living, made up
            of components such as housing, food, transportation and energy.
            Inflation-indexed bonds issued by a foreign government are gener-
            ally adjusted to reflect a comparable inflation index, calculated
            by that government. There can be no assurance that the CPI-U or
            any foreign inflation index will accurately measure the real rate
            of inflation in the prices of goods and services. Moreover, there
            can be no assurance that the rate of inflation in a foreign coun-
            try will be correlated to the rate of inflation in the United
            States.
               Any increase in the principal amount of an inflation-indexed
            bond will be considered taxable ordinary income, even though in-
            vestors do not receive their principal until maturity. See "Taxes"
            for information about the possible tax consequences of investing
            in the Real Return Bond Fund and in inflation-indexed bonds.
 
MORTGAGE-   Each of the Funds (except the Municipal Bond Fund) may invest all
RELATED AND of its assets in mortgage- or other asset-backed securities. The
OTHER       value of some mortgage- or asset-backed securities in which the
ASSET-      Funds invest may be particularly sensitive to changes in prevail-
BACKED      ing interest rates, and, like the other investments of the Funds,
SECURITIES  the ability of a Fund to successfully utilize these instruments
            may depend in part upon the ability of the Advisor to forecast in-
            terest rates and other economic factors correctly.
 
14  PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
 
            MORTGAGE-PASS-THROUGH SECURITIES are securities representing in-
            terests in "pools" of mortgage loans secured by residential or
            commercial real property in which payments of both interest and
            principal on the securities are generally made monthly, in effect
            "passing through" monthly payments made by the individual borrow-
            ers on the mortgage loans which underlie the securities (net of
            fees paid to the issuer or guarantor of the securities). Early re-
            payment of principal on some mortgage-related securities (arising
            from prepayments of principal due to sale of the underlying prop-
            erty, refinancing, or foreclosure, net of fees and costs which may
            be incurred) may expose a Fund to a lower rate of return upon re-
            investment of principal. Also, if a security subject to prepayment
            has been purchased at a premium, the value of the premium would be
            lost in the event of prepayment. Like other fixed income securi-
            ties, when interest rates rise, the value of a mortgage-related
            security generally will decline; however, when interest rates are
            declining, the value of mortgage-related securities with prepay-
            ment features may not increase as much as other fixed income secu-
            rities. The rate of prepayments on underlying mortgages will af-
            fect the price and volatility of a mortgage-related security, and
            may have the effect of shortening or extending the effective matu-
            rity of the security beyond what was anticipated at the time of
            purchase. To the extent that unanticipated rates of prepayment on
            underlying mortgages increase the effective maturity of a mort-
            gage-related security, the volatility of such security can be ex-
            pected to increase.
               Payment of principal and interest on some mortgage pass-through
            securities (but not the market value of the securities themselves)
            may be guaranteed by the full faith and credit of the U.S. Govern-
            ment (in the case of securities guaranteed by GNMA); or guaranteed
            by agencies or instrumentalities of the U.S. Government (in the
            case of securities guaranteed by FNMA or the Federal Home Loan
            Mortgage Corporation ("FHLMC"), which are supported only by the
            discretionary authority of the U.S. Government to purchase the
            agency's obligations). Mortgage-related securities created by non-
            governmental issuers (such as commercial banks, savings and loan
            institutions, private mortgage insurance companies, mortgage bank-
            ers and other secondary market issuers) may be supported by vari-
            ous forms of insurance or guarantees, including individual loan,
            title, pool and hazard insurance and letters of credit, which may
            be issued by governmental entities, private insurers or the mort-
            gage poolers.
 
            COLLATERALIZED MORTGAGE OBLIGATIONS ("CMOs") are hybrid mortgage-
            related instruments. Interest and pre-paid principal on a CMO are
            paid, in most cases, on a monthly basis. CMOs may be collateral-
            ized by whole mortgage loans but are more typically collateralized
            by portfolios of mortgage pass-through securities guaranteed by
            GNMA, FHLMC, or FNMA. CMOs are structured into multiple classes,
            with each class bearing a different stated maturity. Monthly pay-
            ments of principal, including prepayments, are first returned to
            investors holding the shortest maturity class; investors holding
            the longer maturity classes receive principal only after the first
            class has been retired. CMOs that are issued or guaranteed by the
            U.S. Government or by any of its agencies or instrumentalities
            will be considered U.S. Government securities by the Funds, while
            other CMOs, even if collateralized by U.S. Government securities,
            will have the same status as other privately issued securities for
            purposes of applying a Fund's diversification tests.
 
            COMMERCIAL MORTGAGE-BACKED SECURITIES include securities that re-
            flect an interest in, and are secured by, mortgage loans on com-
            mercial real property. The market for commercial mortgage-backed
            securities developed more recently and in terms of total outstand-
            ing principal amount of issues is relatively small compared to the
            market for residential single-family mortgage-backed securities.
            Many of the risks of investing in commercial mortgage-backed secu-
            rities reflect the risks of investing in the real estate securing
            the underlying mortgage loans. These risks reflect the effects of
            local and other economic conditions on real estate markets, the
            ability of tenants to make loan payments, and the ability of a
            property to attract and retain tenants. Commercial mortgage-backed
            securities may be less liquid and exhibit greater price volatility
            than other types of mortgage-related or asset-backed securities.
 
            MORTGAGE-RELATED SECURITIES include securities other than those
            described above that directly or indirectly represent a participa-
            tion in, or are secured by and payable from, mortgage loans on
            real property, such as mortgage dollar rolls (see "Reverse Repur-
            chase Agreements, Dollar Rolls, and Borrowings"), CMO residuals or
            stripped mortgage-backed securities ("SMBS"), and may be struc-
            tured in classes with rights to receive varying proportions of
            principal and interest.
 
                                                  April 8, 1998 Prospectus 15
<PAGE>
 
               A common type of SMBS will have one class receiving some of the
            interest and most of the principal from the mortgage assets, while
            the other class will receive most of the interest and the remain-
            der of the principal. In the most extreme case, one class will re-
            ceive all of the interest (the interest-only, or "IO" class),
            while the other class will receive all of the principal (the prin-
            cipal-only, or "PO" class). The yield to maturity on an IO class
            is extremely sensitive to the rate of principal payments (includ-
            ing prepayments) on the related underlying mortgage assets, and a
            rapid rate of principal payments may have a material adverse ef-
            fect on a Fund's yield to maturity from these securities. The
            Funds have adopted a policy under which no Fund will invest more
            than 5% (10% in the case of the Total Return Mortgage Fund) of its
            net assets in any combination of IO, PO, or inverse floater secu-
            rities. The Funds may invest in other asset-backed securities that
            have been offered to investors. For a discussion of the character-
            istics of some of these instruments, see the Statement of Addi-
            tional Information.
 
MUNICIPAL   The Municipal Bond Fund invests in Municipal Bonds which are gen-
BONDS       erally issued by states and local governments and their agencies,
            authorities and other instrumentalities. The Municipal Bonds which
            the Municipal Bond Fund may purchase include general obligation
            bonds and limited obligation bonds (or revenue bonds), including
            industrial development bonds issued pursuant to former federal tax
            law. General obligation bonds are obligations involving the credit
            of an issuer possessing taxing power and are payable from such is-
            suer's general revenues and not from any particular source. Lim-
            ited obligation bonds are payable only from the revenues derived
            from a particular facility or class of facilities or, in some
            cases, from the proceeds of a special excise or other specific
            revenue source. Tax-exempt "private activity" bonds and industrial
            development bonds generally are also revenue bonds and thus are
            not payable from the issuer's general revenues. The Municipal Bond
            Fund may invest in Municipal Bonds with credit enhancements such
            as letters of credit, municipal bond insurance and Standby Bond
            Purchase Agreements. The Municipal Bond Fund may also invest in
            municipal lease obligations, as well as securities derived from
            Municipal Bonds, such as residual interest bonds, and participa-
            tion interests.
               Municipal Bonds are subject to credit and market risk. Credit
            risk relates to the ability of the issuer to make payments of
            principal and interest. The ability of an issuer to make such pay-
            ments could be affected by litigation, legislation or other polit-
            ical events or the bankruptcy of the issuer. Market risk relates
            to changes in a security's value as a result of changes in inter-
            est rates. Lower rated Municipal Bonds generally provide higher
            yields but are subject to greater credit and market risk than
            higher quality Municipal Bonds.
 
REPURCHASE  For the purpose of achieving income, each of the Funds may enter
AGREEMENTS  into repurchase agreements, which entail the purchase of a portfo-
            lio-eligible security from a bank or broker-dealer that agrees to
            repurchase the security at the Fund's cost plus interest within a
            specified time (normally one day). If the party agreeing to repur-
            chase should default, as a result of bankruptcy or otherwise, the
            Fund will seek to sell the securities which it holds, which action
            could involve procedural costs or delays in addition to a loss on
            the securities if their value should fall below their repurchase
            price. No Fund will invest more than 15% of its net assets (taken
            at current market value) in repurchase agreements maturing in more
            than seven days.
 
REVERSE     A reverse repurchase agreement involves the sale of a security by
REPURCHASE  a Fund and its agreement to repurchase the instrument at a speci-
AGREEMENTS, fied time and price. Under a reverse repurchase agreement, the
DOLLAR      Fund continues to receive any principal and interest payments on
ROLLS, AND  the underlying security during the term of the agreement. The Fund
BORROWINGS  generally will maintain a segregated account consisting of assets
            determined to be liquid by the Advisor in accordance with proce-
            dures established by the Board of Trustees to cover its obliga-
            tions under reverse repurchase agreements and, to this extent, a
            reverse repurchase agreement (or economically similar transaction)
            will not be considered a "senior security" subject to the 300% as-
            set coverage requirements otherwise applicable to borrowings by a
            Fund.
               A Fund may enter into dollar rolls, in which the Fund sells
            mortgage-backed or other securities for delivery in the current
            month and simultaneously contracts to purchase substantially simi-
            lar securities on a specified future date. In the case of dollar
            rolls involving mortgage-backed securities, the mortgage-backed
            securities that are purchased will be of the
 
16  PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
            same type and will have the same interest rate as those sold, but
            will be supported by different pools of mortgages. The Fund for-
            goes principal and interest paid during the roll period on the se-
            curities sold in a dollar roll, but the Fund is compensated by the
            difference between the current sales price and the lower price for
            the future purchase as well as by any interest earned on the pro-
            ceeds of the securities sold. The Fund also could be compensated
            through the receipt of fee income equivalent to a lower forward
            price. The Fund will maintain a segregated account consisting of
            assets determined to be liquid by the Advisor in accordance with
            procedures established by the Board of Trustees to cover its obli-
            gations under dollar rolls.
               To the extent that positions in reverse repurchase agreements,
            dollar rolls or similar transactions are not covered through the
            maintenance of a segregated account consisting of liquid assets at
            least equal to the amount of any forward purchase commitment, such
            transactions would be subject to the Funds' limitations on
            borrowings, which would restrict
            the aggregate of such transactions (plus any other borrowings) to
            33 1/3% of such Fund's total assets. Apart from such transactions,
            a Fund will not borrow money, except for temporary administrative
            purposes.
 
LOANS OF    For the purpose of achieving income, each Fund may lend its port-
PORTFOLIO   folio securities to brokers, dealers, and other financial institu-
SECURITIES  tions, provided:
                (i)   the loan is secured continuously by collateral consisting
                      of U.S. Government securities, cash or cash equivalents
                      (negotiable certificates of deposit, bankers' acceptances
                      or letters of credit) maintained on a daily mark-to-market
                      basis in an amount at least equal to the current market
                      value of the securities loaned;
                (ii)  the Fund may at any time call the loan and obtain the
                      return of the securities loaned;
                (iii) the Fund will receive any interest or dividends paid on
                      the loaned securities; and
                (iv)  the aggregate market value of securities loaned will not
                      at any time exceed 33 1/3% of the total assets of the
                      Fund.
               Each Fund's performance will continue to reflect changes in the
            value of the securities loaned and will also reflect the receipt
            of either interest, through investment of cash collateral by the
            Fund in permissible investments, or a fee, if the collateral is
            U.S. Government securities. Securities lending involves the risk
            of loss of rights in the collateral or delay in recovery of the
            collateral should the borrower fail to return the security loaned
            or become insolvent. The Funds may pay lending fees to the party
            arranging the loan.
 
 
WHEN-       Each of the Funds may purchase or sell securities on a when-is-
ISSUED,     sued, delayed delivery, or forward commitment basis. These trans-
DELAYED     actions involve a commitment by the Fund to purchase or sell secu-
DELIVERY    rities for a predetermined price or yield, with payment and deliv-
AND FORWARD ery taking place more than seven days in the future, or after a
COMMITMENT  period longer than the customary settlement period for that type
TRANSAC-    of security. When such purchases are outstanding, the Fund will
TIONS       set aside and maintain until the settlement date in a segregated
            account, assets determined to be liquid by the Advisor in accor-
            dance with procedures established by the Board of Trustees, in an
            amount sufficient to meet the purchase price. Typically, no income
            accrues on securities a Fund has committed to purchase prior to
            the time delivery of the securities is made, although a Fund may
            earn income on securities it has deposited in a segregated ac-
            count. When purchasing a security on a when-issued, delayed deliv-
            ery, or forward commitment basis, the Fund assumes the rights and
            risks of ownership of the security, including the risk of price
            and yield fluctuations, and takes such fluctuations into account
            when determining its net asset value. Because the Fund is not re-
            quired to pay for the security until the delivery date, these
            risks are in addition to the risks associated with the Fund's
            other investments. If the Fund remains substantially fully in-
            vested at a time when when-issued, delayed delivery, or forward
            commitment purchases are outstanding, the purchases may result in
            a form of leverage. When the Fund has sold a security on a when-
            issued, delayed delivery, or forward commitment basis, the Fund
            does not participate in future gains or losses with respect to the
            security. If the other party to a transaction fails to deliver or
            pay for the securities, the Fund could miss a favorable price or
            yield opportunity or could suffer a loss. A Fund may dispose of or
            renegotiate a transaction after it is entered into, and may sell
            when-issued or forward commitment securities before they are de-
            livered, which may result in a capital gain or loss. There is no
            percentage limitation on the extent to which the Funds may pur-
            chase or sell securities on a when-issued, delayed delivery, or
            forward commitment basis.
 
                                                     April 8, 1998 Prospectus 17
                                                      
<PAGE>
 
 
 
SHORT SALES Each of the Funds (except the High Yield and StocksPLUS Funds) may
            from time to time effect short sales as part of their overall
            portfolio management strategies, including the use of derivative
            instruments, or to offset potential declines in value of long po-
            sitions in similar securities as those sold short. A short sale
            (other than a short sale against the box) is a transaction in
            which a Fund sells a security it does not own at the time of the
            sale in anticipation that the market price of that security will
            decline. To the extent that a Fund engages in short sales, it must
            (except in the case of short sales "against the box") maintain as-
            set coverage in the form of assets determined to be liquid by the
            Advisor in accordance with procedures established by the Board of
            Trustees, in a segregated account, or otherwise cover its position
            in a permissible manner. A short sale is "against the box" to the
            extent that the Fund contemporaneously owns, or has the right to
            obtain at no added cost, securities identical to those sold short.
 
 
FOREIGN     Each of the Funds (except the Municipal Bond Fund) may invest di-
SECURITIES  rectly in fixed income securities of non-U.S. issuers. The Total
            Return Mortgage and High Yield Funds may only invest in U.S. dol-
            lar-denominated fixed income securities of non-U.S. issuers. The
            StocksPLUS Fund may invest directly in foreign equity securities.
               Each of the Funds will concentrate its foreign investments in
            securities of issuers based in developed countries. However, the
            Short-Term and Low Duration Funds may each invest up to 5% of its
            assets in securities of issuers based in emerging market coun-
            tries, and each of the remaining Fixed Income Funds that may in-
            vest in foreign securities may invest up to 10% of its assets in
            such securities.
               Individual foreign economies may differ favorably or unfavor-
            ably from the U.S. economy in such respects as growth of gross do-
            mestic product, rate of inflation, capital reinvestment, re-
            sources, self-sufficiency and balance of payments position. The
            securities markets, values of securities, yields, and risks asso-
            ciated with securities markets in different countries may change
            independently of each other. Investing in the securities of is-
            suers in any foreign country involves special risks and considera-
            tions not typically associated with investing in U.S. companies.
            Shareholders should consider carefully the substantial risks in-
            volved in investing in securities issued by companies and govern-
            ments of foreign nations. These risks include: differences in ac-
            counting, auditing and financial reporting standards; generally
            higher commission rates on foreign portfolio transactions; the
            possibility of nationalization, expropriation or confiscatory tax-
            ation; adverse changes in investment or exchange control regula-
            tions (which may include suspension of the ability to transfer
            currency from a country); and political instability which could
            affect U.S. investments in foreign countries. Additionally, for-
            eign securities and dividends and interest payable on those secu-
            rities may be subject to foreign taxes, including taxes withheld
            from payments on those securities. Foreign securities often trade
            with less frequency and volume than domestic securities and there-
            fore may exhibit greater price volatility. Additional costs asso-
            ciated with an investment in foreign securities may include higher
            custodial fees than apply to domestic custodial arrangements and
            transaction costs of foreign currency conversions. Changes in for-
            eign exchange rates also will affect the value of securities de-
            nominated or quoted in currencies other than the U.S. dollar.
               Certain of the Funds will invest in the securities of issuers
            based in countries with developing economies. Investing in devel-
            oping (or "emerging market") countries involves certain risks not
            typically associated with investing in U.S. securities, and im-
            poses risks greater than, or in addition to, risks of investing in
            foreign, developed countries. A number of emerging market coun-
            tries restrict, to varying degrees, foreign investment in securi-
            ties. Repatriation of investment income, capital, and the proceeds
            of sales by foreign investors may require governmental registra-
            tion and/or approval in some emerging market countries. A number
            of the currencies of emerging market countries have experienced
            significant declines against the U.S. dollar in recent years, and
            devaluation may occur subsequent to investments in these curren-
            cies by a Fund. Inflation and rapid fluctuations in inflation
            rates have had, and may continue to have, negative effects on the
            economies and securities markets of certain emerging market coun-
            tries. Many of the emerging securities markets are relatively
            small, have low trading volumes, suffer periods of relative illi-
            quidity, and are characterized by significant price volatility.
            There is a risk in emerging market countries that a future eco-
            nomic or political crisis could lead to price controls, forced
            mergers of companies, expropriation or confiscatory taxation, sei-
            zure, nationalization, or creation of government monopolies, any
            of which may have a detrimental effect on a Fund's investment.
 
18 PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
               Additional risks of investing in emerging market countries may
            include: currency exchange rate fluctuations; greater social, eco-
            nomic and political uncertainty and instability (including the
            risk of war); more substantial governmental involvement in the
            economy; less governmental supervision and regulation of the secu-
            rities markets and participants in those markets; unavailability
            of currency hedging techniques in certain emerging market coun-
            tries; the fact that companies in emerging market countries may be
            newly organized and may be smaller and less seasoned companies;
            the difference in, or lack of, auditing and financial reporting
            standards, which may result in unavailability of material informa-
            tion about issuers; the risk that it may be more difficult to ob-
            tain and/or enforce a judgment in a court outside the United
            States; and significantly smaller market capitalization of securi-
            ties markets. Also, any change in the leadership or policies of
            Eastern European countries, or the countries that exercise a sig-
            nificant influence over those countries, may halt the expansion of
            or reverse the liberalization of foreign investment policies now
            occurring and adversely affect existing investment opportunities.
               In addition, emerging securities markets may have different
            clearance and settlement procedures, which may be unable to keep
            pace with the volume of securities transactions or otherwise make
            it difficult to engage in such transactions. Settlement problems
            may cause a Fund to miss attractive investment opportunities, hold
            a portion of its assets in cash pending investment, or delay in
            disposing of a portfolio security. Such a delay could result in
            possible liability to a purchaser of the security.
               Each of the Fixed Income Funds (except the Municipal Bond Fund)
            may invest in Brady Bonds. Brady Bonds are securities created
            through the exchange of existing commercial bank loans to sover-
            eign entities for new obligations in connection with debt
            restructurings under a debt restructuring plan introduced by for-
            mer U.S. Secretary of the Treasury, Nicholas F. Brady. Brady Bonds
            have been issued only recently, and for that reason do not have a
            long payment history. Brady Bonds may be collateralized or
            uncollateralized, are issued in various currencies (but primarily
            the U.S. dollar), and are actively traded in the over-the-counter
            secondary market. Brady Bonds are not considered to be U.S. Gov-
            ernment securities. In light of the residual risk of Brady Bonds
            and, among other factors, the history of defaults with respect to
            commercial bank loans by public and private entities in countries
            issuing Brady Bonds, investments in Brady Bonds may be viewed as
            speculative. There can be no assurance that Brady Bonds acquired
            by a Fund will not be subject to restructuring arrangements or to
            requests for new credit, which may cause the Fund to suffer a loss
            of interest or principal on any of its holdings. For further in-
            formation, see the Statement of Additional Information.
               Certain of the Funds also may invest in sovereign debt (other
            than Brady Bonds) issued by governments, their agencies or instru-
            mentalities, or other government-related entities located in
            emerging market countries. Holders of sovereign debt may be re-
            quested to participate in the rescheduling of such debt and to ex-
            tend further loans to governmental entities. In addition, there is
            no bankruptcy proceeding by which defaulted sovereign debt may be
            collected.
               A Fund's investments in foreign currency denominated debt obli-
            gations and hedging activities will likely produce a difference
            between its book income and its taxable income. This difference
            may cause a portion of the Fund's income distributions to consti-
            tute returns of capital for tax purposes or require the Fund to
            make distributions exceeding book income to qualify as a regulated
            investment company for federal tax purposes.
 
 
FOREIGN     Foreign currency exchange rates may fluctuate significantly over
CURRENCY    short periods of time. They generally are determined by the forces
TRANS-      of supply and demand in the foreign exchange markets and the rela-
ACTIONS     tive merits of investments in different countries, actual or per-
            ceived changes in interest rates and other complex factors, as
            seen from an international perspective. Currency exchange rates
            also can be affected unpredictably by intervention (or the failure
            to intervene) by U.S. or foreign governments or central banks, by
            currency controls or political developments in the U.S. or abroad.
            For example, significant uncertainty surrounds the proposed intro-
            duction of the euro (a common currency for the European Union) in
            January 1999 and its effect on the value of securities denominated
            in local European currencies. These and other currencies in which
            the Funds' assets are denominated may be devalued against the U.S.
            dollar, resulting in a loss to the Funds.
               All Funds that may invest in securities denominated in foreign
            currencies may buy and sell foreign currencies on a spot and for-
            ward basis to reduce the risks of adverse changes in foreign ex-
            change rates. A forward foreign currency
 
                                                   April 8, 1998 Prospectus 19
<PAGE>
 
            exchange contract involves an obligation to purchase or sell a
            specific currency at a future date, which may be any fixed number
            of days from the date of the contract agreed upon by the parties,
            at a price set at the time of the contract. By entering into a
            forward foreign currency exchange contract, the Fund "locks in"
            the exchange rate between the currency it will deliver and the
            currency it will receive for the duration of the contract. As a
            result, a Fund reduces its exposure to changes in the value of the
            currency it will deliver and increases its exposure to changes in
            the value of the currency it will exchange into. The effect on the
            value of a Fund is similar to selling securities denominated in
            one currency and purchasing securities denominated in another.
            Contracts to sell foreign currency would limit any potential gain
            which might be realized by a Fund if the value of the hedged cur-
            rency increases. A Fund may enter into these contracts for the
            purpose of hedging against foreign exchange risk arising from the
            Fund's investment or anticipated investment in securities denomi-
            nated in foreign currencies. A Fund also may enter into these con-
            tracts for purposes of increasing exposure to a foreign currency
            or to shift exposure to foreign currency fluctuations from one
            country to another. A Fund may use one currency (or a basket of
            currencies) to hedge against adverse changes in the value of an-
            other currency (or a basket of currencies) when exchange rates be-
            tween the two currencies are positively correlated. Each Fund will
            segregate assets determined to be liquid by the Advisor in accor-
            dance with procedures established by the Board of Trustees, in a
            segregated account to cover its obligations under forward foreign
            currency exchange contracts entered into for non-hedging purposes.
               All Funds that may invest in securities denominated in foreign
            currencies may invest in options on foreign currencies and foreign
            currency futures and options thereon. The Funds also may invest in
            foreign currency exchange- related securities, such as foreign
            currency warrants and other instruments whose return is linked to
            foreign currency exchange rates. Each Fund that may invest in se-
            curities denominated in foreign currencies, except the Emerging
            Markets Bond Fund, will use these techniques to hedge at least 75%
            of its exposure to foreign currency. For a description of these
            instruments, see "Derivative Instruments" below and the Statement
            of Additional Information.
 
 
HIGH YIELD  The High Yield Fund invests at least 65% of its assets in fixed
SECURITIES  income securities rated lower than Baa by Moody's or lower than
("JUNK      BBB by S&P but rated at least B by Moody's or S&P (or, if not rat-
BONDS")     ed, of comparable quality). In addition, each of the Short-Term,
            Low Duration, Total Return, Foreign Bond, Strategic Balanced and
            StocksPLUS Funds may invest up to 10% of its assets in such secu-
            rities. The Municipal Bond Fund may invest up to 10% of its assets
            in securities rated lower than Baa by Moody's or BBB by S&P but
            rated at least Ba by Moody's or BB by S&P. Securities rated lower
            than Baa by Moody's or lower than BBB by S&P are sometimes re-
            ferred to as "high yield" or "junk" bonds. Securities rated Baa
            are considered by Moody's to have some speculative characteris-
            tics. Investors should consider the following risks associated
            with high yield securities before investing in these Funds.
               Investing in high yield securities involves special risks in
            addition to the risks associated with investments in higher rated
            fixed income securities. High yield securities may be regarded as
            predominately speculative with respect to the issuer's continuing
            ability to meet principal and interest payments. Analysis of the
            creditworthiness of issuers of high yield securities may be more
            complex than for issuers of higher quality debt securities, and
            the ability of a Fund to achieve its investment objective may, to
            the extent of its investments in high yield securities, be more
            dependent upon such creditworthiness analysis than would be the
            case if the Fund were investing in higher quality securities.
               High yield securities may be more susceptible to real or per-
            ceived adverse economic and competitive industry conditions than
            higher grade securities. The prices of high yield securities have
            been found to be less sensitive to interest rate changes than more
            highly rated investments, but more sensitive to adverse economic
            downturns or individual corporate developments. A projection of an
            economic downturn or of a period of rising interest rates, for ex-
            ample, could cause a decline in high yield security prices because
            the advent of a recession could lessen the ability of a highly
            leveraged company to make principal and interest payments on its
            debt securities. If the issuer of high yield securities defaults,
            a Fund may incur additional expenses to seek recovery. In the case
            of high yield securities structured as zero coupon or payment-in-
            kind securities, the market prices of such securities are affected
            to a greater extent by interest rate changes, and therefore tend
            to be more volatile than securities which pay interest periodi-
            cally and in cash.
 
20 PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
               The secondary markets on which high yield securities are traded
            may be less liquid than the market for higher grade securities.
            Less liquidity in the secondary trading markets could adversely
            affect and cause large fluctuations in the daily net asset value
            of a Fund's shares. Adverse publicity and investor perceptions,
            whether or not based on fundamental analysis, may decrease the
            values and liquidity of high yield securities, especially in a
            thinly traded market.
               The use of credit ratings as the sole method of evaluating high
            yield securities can involve certain risks. For example, credit
            ratings evaluate the safety of principal and interest payments,
            not the market value risk of high yield securities. Also, credit
            rating agencies may fail to change credit ratings in a timely
            fashion to reflect events since the security was last rated. The
            Advisor does not rely solely on credit ratings when selecting se-
            curities for the Funds, and develops its own independent analysis
            of issuer credit quality. If a credit rating agency changes the
            rating of a portfolio security held by a Fund, the Fund may retain
            the portfolio security if the Advisor deems it in the best inter-
            est of shareholders.
               During the year ended March 31, 1997, based upon the dollar-
            weighted average ratings of the Funds' portfolio holdings at the
            end of each month in the Funds' fiscal year, each operational Fund
            that may invest greater than 5% of its assets in securities rated
            below investment grade had the following percentages of its net
            assets invested in securities rated in the categories indicated as
            rated by Moody's (or, if unrated, determined by the Advisor to be
            of comparable quality). See "Appendix B--Description of Securities
            Ratings," for further information.
 
 
              FIXED INCOME SECURITIES RATINGS
 
<TABLE>
<CAPTION>
                                                       BELOW
           FUND                PRIME 1 Aaa  Aa    A   PRIME 1 Baa  Ba    B
           -----------------------------------------------------------------
           <S>                 <C>     <C>  <C>  <C>  <C>     <C>  <C>  <C>
           SHORT-TERM             31%   26%   3%  12%     0%   20%   7%   1%
           -----------------------------------------------------------------
           LOW DURATION           24    55    1    3      0    13    4    0
           -----------------------------------------------------------------
           TOTAL RETURN           13    66    2    4      0     9    5    1
           -----------------------------------------------------------------
           HIGH YIELD              6     1    0    0      0     3   48   42
           -----------------------------------------------------------------
           FOREIGN BOND           21    58   14    0      0     3    4    0
           -----------------------------------------------------------------
           STRATEGIC BALANCED      7    36    0    8      0    38    9    2
           -----------------------------------------------------------------
           STOCKSPLUS             32    29    5    7      0    17    9    1
</TABLE>
 
 
               These figures are intended solely to provide disclosure about
            each Fund's asset composition during its most recent fiscal year.
            The asset composition after this time may or may not be approxi-
            mately the same as represented by such figures. In addition, the
            categories reflect ratings by Moody's, and ratings assigned by S&P
            may not be consistent with ratings assigned by Moody's or other
            credit ratings services, and the Advisor may not necessarily agree
            with a rating assigned by any credit rating agency.
 
 
DERIVATIVE  To the extent permitted by the investment objectives and policies
INSTRUMENTS of the Funds, the Funds may purchase and write call and put op-
            tions on securities, securities indexes and foreign currencies,
            and enter into futures contracts and use options on futures con-
            tracts as further described below. The Funds (except the Municipal
            Bond Fund) also may enter into swap agreements with respect to
            foreign currencies, interest rates, and securities indexes. The
            Funds may use these techniques to hedge against changes in inter-
            est rates, foreign currency exchange rates or securities prices or
            as part of their overall investment strategies. The Funds (except
            the Municipal Bond Fund) may also purchase and sell options relat-
            ing to foreign currencies for purposes of increasing exposure to a
            foreign currency or to shift exposure to foreign currency fluctua-
            tions from one country to another. Each Fund will maintain a seg-
            regated account consisting of assets determined to be liquid by
            the Advisor in accordance with procedures established by the Board
            of Trustees (or, as permitted by applicable regulation, enter into
            certain offsetting positions) to cover its obligations under op-
            tions, futures, and swaps to limit leveraging of the Fund.

                                                    April 8, 1998 Prospectus 21
                                                                             
<PAGE>
 
               Derivative instruments are considered for these purposes to
            consist of securities or other instruments whose value is derived
            from or related to the value of some other instrument or asset,
            and not to include those securities whose payment of principal
            and/or interest depends upon cash flows from underlying assets,
            such as mortgage-related or asset-backed securities. Each Fund
            (except the Municipal Bond Fund) may invest all of its assets in
            derivative instruments, subject only to the Fund's investment ob-
            jective and policies. The value of some derivative instruments in
            which the Funds invest may be particularly sensitive to changes in
            prevailing interest rates, and, like the other investments of the
            Funds, the ability of a Fund to successfully utilize these instru-
            ments may depend in part upon the ability of the Advisor to fore-
            cast interest rates and other economic factors correctly. If the
            Advisor incorrectly forecasts such factors and has taken positions
            in derivative instruments contrary to prevailing market trends,
            the Funds could be exposed to the risk of loss.
               The Funds might not employ any of the strategies described be-
            low, and no assurance can be given that any strategy used will
            succeed. If the Advisor incorrectly forecasts interest rates, mar-
            ket values or other economic factors in utilizing a derivatives
            strategy for a Fund, the Fund might have been in a better position
            if it had not entered into the transaction at all. The use of
            these strategies involves certain special risks, including a pos-
            sible imperfect correlation, or even no correlation, between price
            movements of derivative instruments and price movements of related
            investments. While some strategies involving derivative instru-
            ments can reduce the risk of loss, they can also reduce the oppor-
            tunity for gain or even result in losses by offsetting favorable
            price movements in related investments or otherwise, due to the
            possible inability of a Fund to purchase or sell a portfolio secu-
            rity at a time that otherwise would be favorable or the possible
            need to sell a portfolio security at a disadvantageous time be-
            cause the Fund is required to maintain asset coverage or offset-
            ting positions in connection with transactions in derivative in-
            struments, and the possible inability of a Fund to close out or to
            liquidate its derivatives positions.
 
            OPTIONS ON SECURITIES, SECURITIES INDEXES, AND CURRENCIES A Fund
            may purchase put options on securities and indexes. One purpose of
            purchasing put options is to protect holdings in an underlying or
            related security against a substantial decline in market value. A
            Fund may also purchase call options on securities and indexes. One
            purpose of purchasing call options is to protect against substan-
            tial increases in prices of securities the Fund intends to pur-
            chase pending its ability to invest in such securities in an or-
            derly manner. An option on a security (or index) is a contract
            that gives the holder of the option, in return for a premium, the
            right to buy from (in the case of a call) or sell to (in the case
            of a put) the writer of the option the security underlying the op-
            tion (or the cash value of the index) at a specified exercise
            price at any time during the term of the option. The writer of an
            option on a security has the obligation upon exercise of the op-
            tion to deliver the underlying security upon payment of the exer-
            cise price or to pay the exercise price upon delivery of the un-
            derlying security. Upon exercise, the writer of an option on an
            index is obligated to pay the difference between the cash value of
            the index and the exercise price multiplied by the specified mul-
            tiplier for the index option. An index is designed to reflect
            specified facets of a particular financial or securities market, a
            specific group of financial instruments or securities, or certain
            economic indicators.
               A Fund may sell put or call options it has previously pur-
            chased, which could result in a net gain or loss depending on
            whether the amount realized on the sale is more or less than the
            premium and other transaction costs paid on the put or call option
            which is sold. A Fund may write a call or put option only if the
            option is "covered" by the Fund holding a position in the under-
            lying securities or by other means which would permit immediate
            satisfaction of the Fund's obligation as writer of the option.
            Prior to exercise or expiration, an option may be closed out by an
            offsetting purchase or sale of an option of the same series.
               The Funds may write covered straddles consisting of a combina-
            tion of a call and a put written on the same underlying security.
            A straddle will be covered when sufficient assets are deposited to
            meet the Funds' immediate obligations. The Funds may use the same
            liquid assets to cover both the call and put options where the ex-
            ercise price of the call and put are the same, or the exercise
            price of the call is higher than that of the put. In such cases,
            the Funds will also segregate liquid assets equivalent to the
            amount, if any, by which the put is "in the money."
 
22 PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
               The purchase and writing of options involves certain risks.
            During the option period, the covered call writer has, in return
            for the premium on the option, given up the opportunity to profit
            from a price increase in the underlying security above the exer-
            cise price, but, as long as its obligation as a writer continues,
            has retained the risk of loss should the price of the underlying
            security decline. The writer of an option has no control over the
            time when it may be required to fulfill its obligation as a writer
            of the option. Once an option writer has received an exercise no-
            tice, it cannot effect a closing purchase transaction in order to
            terminate its obligation under the option and must deliver the un-
            derlying security at the exercise price. If a put or call option
            purchased by the Fund is not sold when it has remaining value, and
            if the market price of the underlying security remains equal to or
            greater than the exercise price (in the case of a put), or remains
            less than or equal to the exercise price (in the case of a call),
            the Fund will lose its entire investment in the option. Also,
            where a put or call option on a particular security is purchased
            to hedge against price movements in a related security, the price
            of the put or call option may move more or less than the price of
            the related security. There can be no assurance that a liquid mar-
            ket will exist when a Fund seeks to close out an option position.
            Furthermore, if trading restrictions or suspensions are imposed on
            the options markets, a Fund may be unable to close out a position.
               Funds that invest in foreign currency-denominated securities
            may buy or sell put and call options on foreign currencies. Cur-
            rency options traded on U.S. or other exchanges may be subject to
            position limits which may limit the ability of a Fund to reduce
            foreign currency risk using such options.
               Over-the-counter options in which certain Funds may invest dif-
            fer from traded options in that they are two-party contracts, with
            price and other terms negotiated between buyer and seller, and
            generally do not have as much market liquidity as exchange-traded
            options. The Funds may be required to treat as illiquid over-the-
            counter options purchased and securities being used to cover cer-
            tain written over-the-counter options.
 
            SWAP AGREEMENTS The Funds (except the Municipal Bond Fund) may en-
            ter into interest rate, index, equity and currency exchange rate
            swap agreements. These transactions would be entered into in an
            attempt to obtain a particular return when it is considered desir-
            able to do so, possibly at a lower cost to the Fund than if the
            Fund had invested directly in the asset that yielded the desired
            return. Swap agreements are two-party contracts entered into pri-
            marily by institutional investors for periods ranging from a few
            weeks to more than one year. In a standard swap transaction, two
            parties agree to exchange the returns (or differentials in rates
            of return) earned or realized on particular predetermined invest-
            ments or instruments, which may be adjusted for an interest fac-
            tor. The gross returns to be exchanged or "swapped" between the
            parties are generally calculated with respect to a "notional
            amount," i.e., the return on or increase in value of a particular
            dollar amount invested at a particular interest rate, in a partic-
            ular foreign currency, or in a "basket" of securities representing
            a particular index. Forms of swap agreements include interest rate
            caps, under which, in return for a premium, one party agrees to
            make payments to the other to the extent that interest rates ex-
            ceed a specified rate, or "cap"; interest rate floors, under
            which, in return for a premium, one party agrees to make payments
            to the other to the extent that interest rates fall below a speci-
            fied level, or "floor"; and interest rate collars, under which a
            party sells a cap and purchases a floor or vice versa in an at-
            tempt to protect itself against interest rate movements exceeding
            given minimum or maximum levels.
               Most swap agreements entered into by the Funds calculate the
            obligations of the parties to the agreement on a "net basis." Con-
            sequently, a Fund's current obligations (or rights) under a swap
            agreement will generally be equal only to the net amount to be
            paid or received under the agreement based on the relative values
            of the positions held by each party to the agreement (the "net
            amount"). A Fund's current obligations under a swap agreement will
            be accrued daily (offset against amounts owed to the Fund), and
            any accrued but unpaid net amounts owed to a swap counterparty
            will be covered by the maintenance of a segregated account con-
            sisting of assets determined to be liquid by the Advisor in accor-
            dance with procedures established by the Board of Trustees, to
            limit any potential leveraging of the Fund's portfolio. Obliga-
            tions under swap agreements so covered will not be construed to be
            "senior securities" for purposes of the Funds' investment restric-
            tion concerning senior securities. A Fund will not enter into a
            swap agreement with any single party if the net amount owed or to
            be received under existing contracts with that party would exceed
            5% of the Fund's assets.
 
                                                    April 8, 1998 Prospectus 23
<PAGE>
 
               Whether a Fund's use of swap agreements will be successful in
            furthering its investment objective will depend on the Advisor's
            ability to predict correctly whether certain types of investments
            are likely to produce greater returns than other investments. Be-
            cause they are two-party contracts and because they may have terms
            of greater than seven days, swap agreements may be considered to
            be illiquid investments. Moreover, a Fund bears the risk of loss
            of the amount expected to be received under a swap agreement in
            the event of the default or bankruptcy of a swap agreement
            counterparty. The Funds will enter into swap agreements only with
            counterparties that meet certain standards for creditworthiness
            (generally, such counterparties would have to be eligible
            counterparties under the terms of the Funds' repurchase agreement
            guidelines). Certain restrictions imposed on the Funds by the In-
            ternal Revenue Code may limit the Funds' ability to use swap
            agreements. The swaps market is a relatively new market and is
            largely unregulated. It is possible that developments in the swaps
            market, including potential government regulation, could adversely
            affect a Fund's ability to terminate existing swap agreements or
            to realize amounts to be received under such agreements.
 
            FUTURES CONTRACTS AND OPTIONS ON FUTURES CONTRACTS Each of the
            Fixed Income Funds (except the Municipal Bond Fund) may invest in
            interest rate futures contracts and options thereon ("futures op-
            tions"), and to the extent it may invest in foreign currency-de-
            nominated securities, may also invest in foreign currency futures
            contracts and options thereon. The Municipal Bond Fund may pur-
            chase and sell futures contracts on U.S. Government securities and
            Municipal Bonds, as well as purchase put and call options on such
            futures contracts. The StocksPLUS Fund may invest in interest
            rate, stock index and foreign currency futures contracts and op-
            tions thereon.
               There are several risks associated with the use of futures and
            futures options for hedging purposes. There can be no guarantee
            that there will be a correlation between price movements in the
            hedging vehicle and in the portfolio securities being hedged. An
            incorrect correlation could result in a loss on both the hedged
            securities in a Fund and the hedging vehicle, so that the portfo-
            lio return might have been greater had hedging not been attempted.
            There can be no assurance that a liquid market will exist at a
            time when a Fund seeks to close out a futures contract or a
            futures option position. Most futures exchanges and boards of
            trade limit the amount of fluctuation permitted in futures con-
            tract prices during a single day; once the daily limit has been
            reached on a particular contract, no trades may be made that day
            at a price beyond that limit. In addition, certain of these in-
            struments are relatively new and without a significant trading
            history. As a result, there is no assurance that an active second-
            ary market will develop or continue to exist. Lack of a liquid
            market for any reason may prevent a Fund from liquidating an unfa-
            vorable position, and the Fund would remain obligated to meet mar-
            gin requirements until the position is closed.
               The Funds may write covered straddles consisting of a call and
            a put written on the same underlying futures contract. A straddle
            will be covered when sufficient assets are deposited to meet the
            Funds' immediate obligations. A Fund may use the same liquid as-
            sets to cover both the call and put options where the exercise
            price of the call and put are the same, or the exercise price of
            the call is higher than that of the put. In such cases, the Funds
            will also segregate liquid assets equivalent to the amount, if
            any, by which the put is "in the money."
               The Funds will only enter into futures contracts or futures op-
            tions which are standardized and traded on a U.S. or foreign ex-
            change or board of trade, or similar entity, or quoted on an auto-
            mated quotation system. Each Fund will use financial futures con-
            tracts and related options only for "bona fide hedging" purposes,
            as such term is defined in applicable regulations of the CFTC or,
            with respect to positions in financial futures and related options
            that do not qualify as "bona fide hedging" positions, will enter
            such positions only to the extent that aggregate initial margin
            deposits plus premiums paid by it for open futures option posi-
            tions, less the amount by which any such positions are "in-the-
            money," would not exceed 5% of the Fund's net assets.
 
 
HYBRID      A hybrid instrument can combine the characteristics of securities,
INSTRUMENTS futures, and options. For example, the principal amount or inter- 
            est rate of a hybrid could be tied (positively or negatively) to  
            the price of some commodity, currency or securities index or an-  
            other interest rate (each a "benchmark"). The interest rate or    
            (unlike most fixed income securi-                                  
 
24 PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
            ties) the principal amount payable at maturity of a hybrid secu-
            rity may be increased or decreased, depending on changes in the
            value of the benchmark.
               Hybrids can be used as an efficient means of pursuing a variety
            of investment goals, including currency hedging, duration manage-
            ment, and increased total return. Hybrids may not bear interest or
            pay dividends. The value of a hybrid or its interest rate may be a
            multiple of a benchmark and, as a result, may be leveraged and
            move (up or down) more steeply and rapidly than the benchmark.
            These benchmarks may be sensitive to economic and political
            events, such as commodity shortages and currency devaluations,
            which cannot be readily foreseen by the purchaser of a hybrid. Un-
            der certain conditions, the redemption value of a hybrid could be
            zero. Thus, an investment in a hybrid may entail significant mar-
            ket risks that are not associated with a similar investment in a
            traditional, U.S. dollar-denominated bond that has a fixed princi-
            pal amount and pays a fixed rate or floating rate of interest. The
            purchase of hybrids also exposes a Fund to the credit risk of the
            issuer of the hybrids. These risks may cause significant fluctua-
            tions in the net asset value of the Fund. Accordingly, no Fund
            will invest more than 5% of its assets in hybrid instruments.
               Certain issuers of structured products such as hybrid instru-
            ments may be deemed to be investment companies as defined in the
            1940 Act. As a result, the Funds' investments in these products
            will be subject to limits applicable to investments in investment
            companies and may be subject to restrictions contained in the 1940
            Act.
 
 
INVESTMENT  Each of the Funds may invest in securities of other investment
IN          companies, such as closed-end management investment companies, or
INVESTMENT  in pooled accounts or other investment vehicles. As a shareholder
COMPANIES   of an investment company, a Fund may indirectly bear service and
            other fees which are in addition to the fees the Fund pays its
            service providers.
 
 
PORTFOLIO   The length of time a Fund has held a particular security is not
TURNOVER    generally a consideration in investment decisions. The investment
            policies of a Fund may lead to frequent changes in the Fund's in-
            vestments, particularly in periods of volatile market movements.
            High portfolio turnover (e.g., over 100%) involves correspondingly
            greater expenses to a Fund, including commissions or dealer mark-
            ups and other transaction costs on the sale of securities and
            reinvestments in other securities. See "Management of the Trust--
            Portfolio Transactions." Such sales may result in realization of
            taxable capital gains. See "Taxes." The portfolio turnover rate
            for the following Funds for the last two fiscal years (1997 and
            1996, respectively) was: Short-Term--77% and 215%; Low Duration--
            240% and 209%; Total Return--173% and 221%; High Yield--67% and
            66%; and Foreign Bond--984% and 1,234%.
 
 
ILLIQUID    Each of the Funds may invest up to 15% of its net assets in illiq-
SECURITIES  uid securities. Certain illiquid securities may require pricing at
            fair value as determined in good faith under the supervision of
            the Board of Trustees. The Advisor may be subject to significant
            delays in disposing of illiquid securities, and transactions in
            illiquid securities may entail registration expenses and other
            transaction costs that are higher than those for transactions in
            liquid securities. The term "illiquid securities" for this purpose
            means securities that cannot be disposed of within seven days in
            the ordinary course of business at approximately the amount at
            which a Fund has valued the securities. Illiquid securities are
            considered to include, among other things, written over-the-
            counter options, securities or other liquid assets being used as
            cover for such options, repurchase agreements with maturities in
            excess of seven days, certain loan participation interests, fixed
            time deposits which are not subject to prepayment or provide for
            withdrawal penalties upon prepayment (other than overnight depos-
            its), securities that are subject to legal or contractual restric-
            tions on resale and other securities which legally or in the Advi-
            sor's opinion may be deemed illiquid (not including securities is-
            sued pursuant to Rule 144A under the Securities Act of 1933 and
            certain commercial paper that Pacific Investment Management has
            determined to be liquid under procedures approved by the Board of
            Trustees).
               Illiquid securities may include privately placed securities,
            which are sold directly to a small number of investors, usually
            institutions. Unlike public offerings, such securities are not
            registered under the federal securities laws. Although certain of
            these securities may be readily sold, for example, under Rule
            144A, others may be illiquid, and their sale may involve substan-
            tial delays and additional costs.

                                                   April 8, 1998 Prospectus 25
                                                                              
<PAGE>
 
 
SERVICE     Many of the services provided to the Funds depend on the smooth
SYSTEMS--   functioning of computer systems. Many systems in use today cannot
YEAR 2000   distinguish between the year 1900 and the year 2000. Should any of
PROBLEM     the service systems fail to process information properly, that
            could have an adverse impact on the Funds' operations and services
            provided to shareholders. The Advisor, Distributor, Shareholder
            Servicing and Transfer Agent, Custodian, and certain other service
            providers to the Funds have reported that each is working toward
            mitigating the risks associated with the so-called "year 2000
            problem." However, there can be no assurance that the problem will
            be corrected in all respects and that the Funds' operations and
            services provided to shareholders will not be adversely affected.
 
            Performance Information
 
            From time to time the Trust may make available certain information
            about the performance of the Class D shares of some or all of the
            Funds. Information about a Fund's performance is based on that
            Fund's (or its predecessor's) record to a recent date and is not
            intended to indicate future performance.
               From time to time, the yield and total return for each class of
            shares of the Funds may be included in advertisements or reports
            to shareholders or prospective investors. Quotations of yield for
            a Fund or class will be based on the investment income per share
            (as defined by the Securities and Exchange Commission) during a
            particular 30-day (or one-month) period (including dividends and
            interest), less expenses accrued during the period ("net invest-
            ment income"), and will be computed by dividing net investment in-
            come by the maximum public offering price per share on the last
            day of the period. The tax equivalent yield of the Municipal Bond
            Fund's Class D shares may also be advertised, calculated like
            yield except that, for any given tax bracket, net investment in-
            come will be calculated as the sum of (i) any taxable income of
            the class plus (ii) the tax exempt income of the class divided by
            the difference between 1 and the effective federal income tax
            rates for taxpayers in that tax bracket.
               The total return of Class D shares of all Funds may be included
            in advertisements or other written material. When a Fund's total
            return is advertised with respect to its Class D shares, it will
            be calculated for the past year, the past five years, and the past
            ten years (or if the Fund has been offered for a period shorter
            than one, five or ten years, that period will be substituted)
            since the establishment of the Fund as more fully described in the
            Statement of Additional Information. Consistent with Securities
            and Exchange Commission rules and informal guidance, for periods
            prior to the initial offering date of Class D shares, total return
            presentations for the Class D shares will be based on the histori-
            cal performance of an older class of the Fund (the older class to
            be used in each case is set forth in the Statement of Additional
            Information) restated, as necessary, to reflect that there are no
            sales charges associated with Class D shares, but not reflecting
            any different operating expenses (such as administrative fee
            and/or 12b-1/servicing fee charges) associated with Class D
            shares. All other things being equal, any higher expenses of Class
            D shares would have adversely affected (i.e., reduced) total re-
            turn for Class D shares (i.e., if the Class D shares had been is-
            sued since the inception of the Fund) by the amount of such higher
            expenses, compounded over the relevant period. Total return is
            measured by comparing the value of an investment in Class D shares
            of the Fund at the beginning of the relevant period to the redemp-
            tion value of the investment in the Fund at the end of the period
            (assuming immediate reinvestment of any dividends or capital gains
            distributions at net asset value). Total return may be advertised
            using alternative methods that reflect all elements of return, but
            that may be adjusted to reflect the cumulative impact of alterna-
            tive fee and expense structures, such as the currently effective
            advisory and administrative fees for Class D shares of the Funds.
               The Funds may also provide current distribution information to
            its shareholders in shareholder reports or other shareholder com-
            munications, or in certain types of sales literature provided to
            prospective investors. Current distribution information for a
            Class D shares of a Fund will be based on distributions for a
            specified period (i.e., total dividends from net investment in-
            come), divided by the net asset value per Class D share on the
            last day of the period and annualized. The rate of current distri-
            butions does not reflect deductions for unrealized losses from
            transactions in derivative instruments such as options and
            futures, which may reduce total return. Current distribution rates
            differ from standardized
 
26 PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
            yield rates in that they represent what Class D shares of a Fund
            have declared and paid to shareholders as of the end of a speci-
            fied period rather than the Fund's actual net investment income
            for that period.
               Performance information for the Trust may also be compared to
            various unmanaged indexes, such as the S&P 500, the Lehman Broth-
            ers Aggregate Bond Index, the Lehman Brothers Mortgage-Backed Se-
            curities Index, the Merrill Lynch 1 to 3 Year Treasury Index, the
            Lehman Intermediate and 20+ Year Treasury Blend Index, the Lehman
            Inflation Linked Treasury Index, the Lehman Muncipal Bond Index,
            the Lehman BB Intermediate Corporate Index, indexes prepared by
            Lipper Analytical Services, the J.P. Morgan Global Index, the J.P.
            Morgan Emerging Markets Bond Index Plus, the Salomon Brothers
            World Government Bond Index-10 Non U.S.-Dollar Hedged and the J.P.
            Morgan Government Bond Index Non U.S.-Dollar Hedged, and other en-
            tities or organizations which track the performance of investment
            companies or investment advisers. Unmanaged indexes (i.e., other
            than Lipper) generally do not reflect deductions for administra-
            tive and management costs and expenses. The Advisor may also re-
            port to shareholders or to the public in advertisements concerning
            the performance of the Advisor as adviser to clients other than
            the Trust, and on the comparative performance or standing of the
            Advisor in relation to other money managers. Such comparative in-
            formation may be compiled or provided by independent ratings serv-
            ices or by news organizations. Any performance information,
            whether related to the Funds or to the Advisor, should be consid-
            ered in light of the Funds' investment objectives and policies,
            characteristics and quality of the portfolio, and the market con-
            ditions during the time period indicated, and should not be con-
            sidered to be representative of what may be achieved in the fu-
            ture. For a description of the methods used to determine yield and
            total return for the Funds, see the Statement of Additional Infor-
            mation.
               Investment results of the Funds will fluctuate over time, and
            any presentation of the Funds' total return or yield for any prior
            period should not be considered as a representation of what an in-
            vestor's total return or yield may be in any future period.
 
            How to Buy Shares
 
            Class D shares of each Fund are continuously offered through fi-
            nancial service firms, such as broker-dealers or registered in-
            vestment advisers, with which the Trust's principal underwriter,
            PIMCO Funds Distributors LLC (the "Distributor"), has an agreement
            for the use of the Funds in particular investment products, pro-
            grams or accounts for which a fee may be charged. See "Financial
            Service Firms" below.
               You may purchase Class D shares only through your financial
            service firm. In connection with purchases, your financial service
            firm is responsible for forwarding all necessary documentation to
            the Distributor, and may charge you for such services. Investors
            who wish to purchase shares of the Funds directly from the Trust
            or the Distributor should inquire as to the other classes of
            shares. See "Description of the Trust--Multiple Classes of
            Shares."
               Class D shares may be purchased at a price equal to their net
            asset value per share next determined after receipt of an order.
            Purchase payments for Class D shares are fully invested at the net
            asset value next determined after acceptance of the trade. All
            purchase orders received by the Distributor from your financial
            service firm prior to the close of regular trading (normally 4:00
            p.m., Eastern time) on the New York Stock Exchange (the "Ex-
            change"), on a regular business day, are processed at that day's
            offering price. In addition, orders received by the Distributor
            from financial service firms after the offering price is deter-
            mined that day will receive such offering price if the orders were
            received by the firm from its customer prior to such determination
            and were transmitted to and received by the Distributor prior to
            its close of business that day (normally 7:00 p.m., Eastern time).
            Purchase orders received on other than a regular business day will
            be executed on the next succeeding regular business day.
               The Distributor, in its sole discretion, may accept or reject
            any order for purchase of Fund shares. The sale of shares will be
            suspended during any period in which the Exchange is closed for
            other than weekends or holidays, or if

                                                    April 8, 1998 Prospectus 27
                                                                             
<PAGE>
 
            permitted by the rules of the Securities and Exchange Commission,
            when trading on the Exchange is restricted or during an emergency
            which makes it impracticable for the Funds to dispose of their se-
            curities or to determine fairly the value of their net assets, or
            during any other period as permitted by the Securities and Ex-
            change Commission for the protection of investors.
               Class D shares of the Funds will be held in your account with
            your financial service firm and, generally, your firm will hold
            your Class D shares in nominee or street name as your agent. Ac-
            cordingly, in most cases, the Trust's transfer agent will have no
            information with respect to or control over accounts of specific
            Class D shareholders and you may obtain information about your ac-
            counts only through your financial service firm. In certain cir-
            cumstances, your firm may arrange to have your shares held in your
            own name or you may subsequently become a holder of record for
            some other reason (for instance, if you terminate your relation-
            ship with your firm). In such circumstances, please contact the
            Distributor at 888-87-PIMCO for information about your account. If
            you wish to invest in the Funds through your own account with the
            Trust or the Distributor, please inquire as to the other classes
            of shares of the Funds. See "Description of the Trust--Multiple
            Classes of Shares." In the interest of economy and convenience,
            certificates for Class D shares will not be issued.
 
 
FINANCIAL   Broker-dealers, registered investment advisors and other financial
SERVICE     service firms provide varying investment products, programs or ac-
FIRMS       counts, pursuant to arrangements with the Distributor, through
            which their clients may purchase and redeem Class D shares of the
            Funds. Firms will generally provide or arrange for the provision
            of some or all of the shareholder servicing and account mainte-
            nance services required by your account, including, without limi-
            tation, transfers of registration and dividend payee changes; and
            may perform functions such as generation of confirmation state-
            ments and disbursement of cash dividends. Firms may also arrange
            with their clients for other investment or administrative servic-
            es. Your firm may independently establish and charge you transac-
            tion fees and/or other additional amounts for such services, which
            charges could reduce your investment returns on Class D shares of
            the Funds.
               Your financial service firm may have omnibus accounts and simi-
            lar arrangements with the Trust and may be paid for providing sub-
            transfer agency and other services. A firm may be paid for its
            services directly or indirectly by the Funds, the Advisor or an
            affiliate (normally not to exceed an annual rate of 0.35% of a
            Fund's average daily net assets attributable to its Class D shares
            and purchased through such firm for its clients). Your firm may
            establish various minimum investment requirements for Class D
            shares of the Funds and may also establish certain privileges with
            respect to purchases, redemptions and exchanges of Class D shares
            or the reinvestment of dividends.
               This Prospectus should be read in connection with your firm's
            materials regarding its fees and services.
 
            Exchange Privilege
 
            A shareholder may exchange Class D shares of any Fund for Class D
            shares of any other Fund in an account with identical registration
            on the basis of their respective net asset values. Class D shares
            of each Fund may also be exchanged for Class D shares of certain
            series of PIMCO Funds: Multi-Manager Series, an affiliated mutual
            fund family composed primarily of stock portfolios managed by
            subsidiaries of PIMCO Advisors L.P., an affiliate of the Advisor.
            There are currently no exchange fees or charges imposed by the
            Trust, although your financial service firm may impose various
            fees and charges, investment minimums and other requirements with
            respect to exchanges. Please contact your financial service firm
            for details. An exchange will constitute a taxable sale for
            federal income tax purposes.
               The Trust reserves the right to refuse exchange purchases if,
            in the judgment of the Advisor, the purchase would adversely af-
            fect a Fund and its shareholders. In particular, a pattern of ex-
            changes characteristic of "market-timing" strategies may be deemed
            by the Advisor to be detrimental to the Trust or a particular
            Fund. Although the Trust has no current intention of terminating
            or modifying the exchange privilege, it reserves the right to do
            so at any time. Except as otherwise permitted by Securities and
            Exchange Commission regulations, the Trust will give 60 days' ad-
            vance notice to your financial service firm of any termination or
            material modification of the exchange privilege. For further in-
            formation about exchange privileges, please contact your financial
            service firm.
 
28 PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
 
            How to Redeem
 
            Class D shares may be redeemed through your financial service firm
            on any day the Exchange is open. Shares are redeemed at their net
            asset value next determined after a proper redemption request has
            been received from your financial service firm. There is no charge
            by the Trust or the Distributor with respect to a redemption, al-
            though your financial service firm may charge you for its services
            in processing your redemption request. Please contact your finan-
            cial service firm for details. If you are the holder of record of
            your Class D shares, you may contact the Distributor at 888-87-
            PIMCO for information regarding how to redeem your shares directly
            from the Trust.
               Your financial service firm is obligated to transmit your re-
            demption orders to the Distributor promptly and is responsible for
            ensuring that your redemption request is in proper form. Requests
            for redemption received by financial service firms prior to the
            close of regular trading (normally 4:00 p.m., Eastern time) on the
            Exchange on a regular business day and received by the Distributor
            prior to the close of the Distributor's business day will be con-
            firmed at the net asset value effective as of the closing of the
            Exchange on that day. Your financial service firm will be respon-
            sible for furnishing all necessary documentation to the Distribu-
            tor or the Trust's transfer agent and may charge you for its serv-
            ices. Redemption proceeds will be forwarded to your financial
            service firm as promptly as possible and in any event within seven
            days after the redemption request is received by the Distributor
            in good order. Under unusual circumstances, the Trust may suspend
            redemptions or postpone payment for more than seven days, as per-
            mitted by federal securities law.
 
            Distributor
 
            The Distributor, a wholly owned subsidiary of PIMCO Advisors L.P.,
            is the principal underwriter of the Trust's shares. Pursuant to a
            Distribution Contract with the Trust, with respect to each Fund's
            Class D shares, the Distributor bears various promotional and
            sales related expenses, including the cost of printing and mailing
            prospectuses to persons other than current shareholders. The Dis-
            tributor, located at 2187 Atlantic Street, Stamford, Connecticut
            06902, is a broker-dealer registered with the SEC.
 
            How Net Asset Value Is Determined
 
            The net asset value per share of Class D shares of each Fund will
            be determined once on each day on which the Exchange is open as of
            the close of regular trading (normally 4:00 p.m., Eastern time) on
            the Exchange by dividing the total market value of a Fund's port-
            folio investments and other assets attributable to that class,
            less any liabilities, by the number of total outstanding shares of
            that class. Net asset value will not be determined on days on
            which the Exchange is closed.
               For all Funds, portfolio securities and other assets for which
            market quotations are readily available are stated at market. Mar-
            ket value is determined on the basis of last reported sales pric-
            es, or if no sales are reported, as is the case for most securi-
            ties traded over-the-counter, at the mean between representative
            bid and asked quotations obtained from a quotation reporting sys-
            tem or from established market makers. Fixed income securities,
            including those to be purchased under firm commitment agreements
            (other than obligations having a maturity of 60 days or less), are
            normally valued on the basis of quotations obtained from brokers
            and dealers or pricing services, which take into account appropri-
            ate factors such as institutional-sized trading in similar groups
            of securities, yield, quality, coupon rate, maturity, type of is-
            sue, trading characteristics, and other market data.
               Quotations of foreign securities in foreign currency are con-
            verted to U.S. dollar equivalents using foreign exchange quota-
            tions received from independent dealers. Short-term investments
            having a maturity of 60 days or less are valued at amortized cost,
            when the Board of Trustees determines that amortized cost is their
            fair value. Certain fixed income securities for which daily market
            quotations are not readily available may be valued, pursuant to
            guidelines

                                                    April 8, 1998 Prospectus 29
                                                                              
<PAGE>
 
            established by the Board of Trustees, with reference to fixed in-
            come securities whose prices are more readily obtainable and whose
            durations are comparable to the securities being valued. Subject
            to the foregoing, other securities for which market quotations are
            not readily available are valued at fair value as determined in
            good faith by the Board of Trustees.
               Each Fund's liabilities are allocated among its classes. The
            total of such liabilities allocated to a class plus that class's
            distribution and/or servicing fees and any other expenses spe-
            cially allocated to that class are then deducted from the class's
            proportionate interest in the Fund's assets, and the resulting
            amount for each class is divided by the number of shares of that
            class outstanding to produce the class's "net asset value" per
            share. Generally, for Funds that pay income dividends, those divi-
            dends are expected to differ over time by approximately the amount
            of the expense accrual differential between a particular Fund's
            classes.
 
            Distributions
 
            Each Fund pays out as dividends substantially all of its net in-
            vestment income (which comes from dividends and interest it re-
            ceives or is deemed to receive from its investments) and net real-
            ized short-term capital gains. For these purposes and for federal
            income tax purposes, a portion of the premiums from certain ex-
            pired call or put options written by the Fund, net gains from
            closing purchase and sale transactions with respect to such op-
            tions, and net gains from futures transactions are treated as
            short-term capital gains. Each Fund distributes substantially all
            of its net realized capital gains, if any, after giving effect to
            any available capital loss carry-over.
               Shares begin earning dividends on the day after the date that
            funds are received by the Trust for the purchase of shares. For
            the Fixed Income Funds, dividends are declared daily from net in-
            vestment income to shareholders of record at the close of the pre-
            vious business day, and distributed to shareholders monthly. The
            StocksPLUS and Strategic Balanced Funds intend to declare and pay
            as a dividend substantially all of their net investment income on
            a quarterly basis. Any net realized capital gains from the sale of
            portfolio securities will be distributed no less frequently than
            once yearly. Dividend and capital gain distributions of a Fund
            will be reinvested in additional shares of that Fund unless the
            shareholder elects to have them paid in cash. There are no sales
            charges on reinvested dividends. If a shareholder has elected to
            receive dividends and/or capital gain distributions in cash and
            the postal or other delivery service is unable to
            deliver checks to the shareholder's address of record, such share-
            holder's distributions will automatically be invested in the Money
            Market Fund until such shareholder is located.
               Your financial service firm may offer a program pursuant to
            which you may elect to invest dividends and/or distributions paid
            by any Fund in shares of the same class of any other Fund of the
            Trust at net asset value. Please contact your financial service
            firm for details.
 
            Taxes
 
            Each Fund intends to qualify as a regulated investment company an-
            nually and to elect to be treated as a regulated investment com-
            pany under the Code. As such, a Fund generally will not pay fed-
            eral income tax on the income and gains it pays as dividends to
            its shareholders. In order to avoid a 4% federal excise tax, each
            Fund intends to distribute each year substantially all of its net
            income and gains.
               Shareholders subject to U.S. federal income tax will be subject
            to tax on dividends received from a Fund, regardless of whether
            received in cash or reinvested in additional shares. Distributions
            received by tax-exempt shareholders generally will not be subject
            to federal income tax to the extent permitted under applicable tax
            law. All shareholders must treat dividends, other than capital
            gain dividends or dividends that represent a return of capital to
            shareholders, as ordinary income.
 
30 PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
               Dividends designated by a Fund as capital gain dividends de-
            rived from the Fund's net capital gain (that is, the excess of net
            long-term gain over net short-term loss) are taxable to sharehold-
            ers as long-term capital gain except as provided by an applicable
            tax exemption. Under the Taxpayer Relief Act of 1997, long-term
            capital gains will generally be taxed at a 28% or 20% rate, de-
            pending upon the holding period of the portfolio securities. Any
            distributions that are not from a Fund's net investment income,
            short-term capital gain, or net capital gain may be characterized
            as a return of capital to shareholders or, in some cases, as capi-
            tal gain. Certain dividends declared in October, November or De-
            cember of a calendar year are taxable to shareholders (who other-
            wise are subject to tax on dividends) as though received on Decem-
            ber 31 of that year if paid to shareholders during January of the
            following calendar year. For state income tax purposes, interest
            on some federal obligations generally is not exempt from taxation,
            whether received directly by a shareholder or through distribu-
            tions of investment company taxable income (for example, interest
            on FNMA and GNMA Certificates). Each Fund will advise shareholders
            annually of the amount and nature of the dividends paid to them.
               Dividends paid to shareholders by the Municipal Bond Fund which
            are derived from interest on Municipal Bonds are expected to be
            designated by the Fund as "exempt-interest dividends," and share-
            holders may generally exclude such dividends from gross income for
            federal income tax purposes. However, if a shareholder receives
            social security or railroad retirement benefits, the shareholder
            may be taxed on a portion of those benefits as a result of receiv-
            ing tax- exempt income. In addition, certain exempt-interest divi-
            dends could, as discussed below, cause certain shareholders to be-
            come subject to the alternative minimum tax and may increase the
            alternative minimum tax liability of shareholders already subject
            to this tax.
               To the extent that dividends paid to shareholders by the Munic-
            ipal Bond Fund are derived from taxable interest or from capital
            gains, such dividends will be subject to federal income tax. Any
            gain realized on a redemption of shares will be taxable gain, sub-
            ject to any applicable tax exemption for which an investor may
            qualify.
               Dividends derived from interest on certain U.S. Government se-
            curities may be exempt from state and local taxes, although inter-
            est on mortgage-backed U.S. Government securities is generally not
            so exempt. The distributions of "exempt-interest dividends" paid
            by the Municipal Bond Fund may be exempt from state and local tax-
            ation when received by a shareholder to the extent that they are
            derived from interest on Municipal Bonds issued by the state or
            political subdivision in which such shareholder resides. The fed-
            eral exemption for "exempt-interest dividends" attributable to Mu-
            nicipal Bonds does not necessarily result in exemption of such
            dividends from income for the purpose of state and local taxes.
            The Trust will report annually on a state-by-state basis the
            source of income the Municipal Bond Fund receives on Municipal
            Bonds that was paid out as dividends during the preceding year.
               The Code also provides that exempt-interest dividends allocable
            to interest received from "private activity bonds" issued after
            August 7, 1986 are an item of tax preference for individual and
            corporate alternative minimum tax at the applicable rate for indi-
            viduals and corporations. Therefore, if the Municipal Bond Fund
            invests in such private activity bonds, certain of its sharehold-
            ers may become subject to the alternative minimum tax on that part
            of its distributions to them that are derived from interest income
            on such bonds, and certain shareholders already subject to such
            tax may have increased liability therefor. However, it is the
            present policy of the Municipal Bond Fund to invest no more than
            20% of its assets in such bonds. Other provisions of the Code af-
            fect the tax treatment of distributions from the Municipal Bond
            Fund for corporations, casualty insurance companies, and financial
            institutions. In particular, under the Code, for corporations, al-
            ternative minimum taxable income will be increased by a percentage
            of the amount by which the corporation's "adjusted current earn-
            ings" (which includes various items of tax exempt income) exceeds
            the amount otherwise determined to be alternative minimum taxable
            income. Accordingly, an investment in the Municipal Bond Fund may
            cause shareholders to be subject to (or result in an increased li-
            ability under) the alternative minimum tax.
               Dividends to shareholders of the Municipal Bond Fund derived
            from money market instruments and U.S. Government securities are
            generally taxable as ordinary income. The Fund may seek to reduce
            fluctuations in its net asset value by engaging in portfolio
            strategies involving options on securities, futures contracts, and
            options on futures contracts. Any gain derived by the Fund from
            the use of such instruments, including by reason of "marking to
            market," will be treated as a combination of short-term and long-
            term capital gain and, if not offset by realized capital losses
            incurred by

                                                     April 8, 1998 Prospectus 31
<PAGE>
 
            the Fund, will be distributed to shareholders (possibly requiring
            the liquidation of other portfolio securities) and will be taxable
            to shareholders as a combination of ordinary income and long-term
            capital gain.
               Interest accrued by a Fund from inflation-indexed bonds will be
            includable in the Fund's gross income in the period in which they
            accrue. Periodic adjustments for inflation in the principal value
            of these securities also may give rise to original issue discount,
            which, likewise, will be includable in the Fund's gross income on
            a current basis, regardless of whether the Fund receives any cash
            payments. See "Taxation--Original Issue Discount" in the Statement
            of Additional Information. Amounts includable in a Fund's gross
            income become subject to tax-related distribution requirements.
            Accordingly, a Fund may be required to make annual distributions
            to shareholders in excess of the cash received in a given period
            from these investments. As a result, the Fund may be required to
            liquidate certain investments at a time when it is not advanta-
            geous to do so. If the principal value of an inflation-indexed
            bond is adjusted downward in any period as a result of deflation,
            the reduction may be treated as a loss to the extent the reduction
            exceeds coupon payments received in that period; in that case, the
            amount distributable by the Fund may be reduced and amounts dis-
            tributed previously in the taxable year may be characterized in
            some circumstances as a return of capital.
               Taxable shareholders should note that the timing of their in-
            vestment could have undesirable tax consequences. If shares are
            purchased on or just before the record date of a dividend, taxable
            shareholders will pay full price for the shares and may receive a
            portion of their investment back as a taxable distribution.
               The preceding discussion relates only to federal income tax;
            the consequences under other tax laws may differ. For additional
            information relating to the tax aspects of investing in a Fund,
            see the Statement of Additional Information.
 
            Management of the Trust
 
            The business affairs of the Trust are managed under the direction
            of the Board of Trustees. The Trustees are Guilford C. Babcock, R.
            Wesley Burns, Vern O. Curtis, Brent R. Harris, Thomas P. Kemp, and
            William J. Popejoy. Additional information about the Trustees and
            the Trust's executive officers may be found in the Statement of
            Additional Information under the heading "Management--Trustees and
            Officers."
 
 
INVESTMENT  Pacific Investment Management serves as investment advisor
ADVISOR     ("Advisor") to the Funds pursuant to an investment advisory
            contract. The Advisor is an investment counseling firm founded in
            1971, and had approximately $118 billion in assets under
            management as of December 31, 1997. Pacific Investment Management
            is a subsidiary of PIMCO Advisors L.P. ("PIMCO Advisors"). The
            general partners of PIMCO Advisors are PIMCO Partners, G.P. and
            PIMCO Advisors Holdings L.P. ("PAH"). PIMCO Partners, G.P. is a
            general partnership between PIMCO Holding LLC, a Delaware limited
            liability company and indirect wholly-owned subsidiary of Pacific
            Life Insurance Company, and PIMCO Partners LLC, a California
            limited liability company controlled by the Managing Directors of
            Pacific Investment Management. PIMCO Partners, G.P. is the sole
            general partner of PAH. Pacific Investment Management's address is
            840 Newport Center Drive, Suite 360, Newport Beach, California
            92660. Pacific Investment Management is registered as an
            investment adviser with the Securities and Exchange Commission and
            as a commodity trading advisor with the CFTC.
               The Advisor manages the investment and reinvestment of the as-
            sets of each Fund. The Advisor is responsible for placing orders
            for the purchase and sale of each Fund's investments directly with
            brokers or dealers selected by it in its discretion. See "Portfo-
            lio Transactions" in the Statement of Additional Information.
 
32 PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
               Information about the individual portfolio managers responsible
            for management of the Trust's currently operational Funds offered
            in this Prospectus, including their occupations for the past five
            years, is provided below.
 
<TABLE>
<CAPTION>
                                      PORTFOLIO MANAGER AND BUSINESS EXPERIENCE
           FUND                       (PAST FIVE YEARS)
           --------------------------------------------------------------------
           <C>                        <S>
           SHORT-TERM FUND            William H. Gross, Managing Director, Pa-
           LOW DURATION FUND          cific Investment Management. A Fixed In-
           TOTAL RETURN FUND          come Portfolio Manager, Mr. Gross is one
           STRATEGIC BALANCED FUND    of the founders of Pacific Investment
           STOCKSPLUS FUND            Management and has managed the Total Re-
                                      turn and Low Duration Funds since their
                                      inception, May 11, 1987. Mr. Gross is the
                                      leader of the team which has managed the
                                      Short-Term , StocksPLUS and Strategic
                                      Balanced Funds since January 6, 1998.
           --------------------------------------------------------------------
           REAL RETURN BOND FUND      John Brynjolfsson, Vice President, Pa-
                                      cific Investment Management. A Fixed In-
                                      come Portfolio Manager, Mr. Brynjolfsson
                                      joined Pacific Investment Management in
                                      1989, and has managed the Real Return
                                      Bond Fund since its inception, January
                                      29, 1997.
           --------------------------------------------------------------------
           TOTAL RETURN MORTGAGE FUND Pasi Hamalainen, Executive Vice Presi-
                                      dent, Pacific Investment Management. A
                                      Fixed Income Portfolio Manager, Mr.
                                      Hamalainen joined Pacific Investment Man-
                                      agement in 1994 and has managed the Total
                                      Return Mortgage Fund since its inception,
                                      July 31, 1997.
           --------------------------------------------------------------------
           HIGH YIELD FUND            Benjamin Trosky, Managing Director, Pa-
                                      cific Investment Management. A Fixed In-
                                      come Portfolio Manager, Mr. Trosky joined
                                      Pacific Investment Management in 1990 and
                                      has managed the High Yield Fund since its
                                      inception, December 16, 1992.
           --------------------------------------------------------------------
           MUNICIPAL BOND FUND        Benjamin Ehlert, Executive Vice Presi-
                                      dent, PIMCO. A Fixed Income Portfolio
                                      Manager, Mr. Ehlert has been associated
                                      with PIMCO for over 23 years.
           --------------------------------------------------------------------
           FOREIGN BOND FUND          Lee R. Thomas, III, Managing Director and
                                      Senior International Portfolio Manager,
                                      Pacific Investment Management. A Fixed
                                      Income Portfolio Manager, Mr. Thomas has
                                      managed the Foreign Bond Fund since July
                                      13, 1995. Prior to joining Pacific In-
                                      vestment Management in 1995, Mr. Thomas
                                      was associated with Investcorp as a mem-
                                      ber of the management committee responsi-
                                      ble for global securities and foreign ex-
                                      change trading. Prior to Investcorp, he
                                      was associated with Goldman Sachs as an
                                      Executive Director in foreign fixed in-
                                      come.
</TABLE>
 
 
 
FUND        Pacific Investment Management also serves as administrator to the
ADMINISTRA- Funds' Class D shares pursuant to an administration agreement with
TOR         the Trust. Pacific Investment Management provides administrative
            services for Class D shareholders of the Funds, which include
            clerical help and accounting, bookkeeping, internal audit servic-
            es, and certain other services required by the Funds, preparation
            of reports to the Funds' shareholders and regulatory filings. Pa-
            cific Investment Management may also retain certain of its affili-
            ates to provide certain of these services. In addition, Pacific
            Investment Management, at its own expense, arranges for the provi-
            sion of legal, audit, custody, transfer agency (including sub-
            transfer agency and other administrative services) and other serv-
            ices for the Funds, and is responsible for the costs of registra-
            tion of the Trust's shares and the printing of prospectuses and
            shareholder reports for current shareholders.
               Pacific Investment Management or an affiliate may pay financial
            service firms a portion of the Class D administration fees in re-
            turn for the firms' services (normally not to exceed an annual
            rate of .35% of a Fund's average daily net assets attributable to
            Class D shares purchased through such firms). The Funds' adminis-
            tration agreement includes a plan for Class D shares that has been
            adopted in conformity with the requirements set forth under Rule
            12b-1 of the 1940 Act to allow for the payment of up to .25% per
            annum of the Class D administrative fees for activities that may
            be deemed to be primarily intended to result in the sale of Class
            D shares. The principal types of activities for which such pay-
            ments may be made are services in connection with the distribution
            of Class D shares and/or the provision of shareholder services.
               The Funds (and not Pacific Investment Management) are responsi-
            ble for the following expenses: (i) salaries and other compensa-
            tion of any of the Trust's executive officers and employees who
            are not officers, directors, stockholders or employees of Pacific
            Investment Management or its subsidiaries or affiliates; (ii)
            taxes and governmental fees; (iii) brokerage fees and commissions
            and other portfolio transaction expenses; (iv) the costs of bor-
            rowing money, including interest expenses; (v) fees and expenses
            of the Trustees who are not "interested persons" of Pacific In-
            vestment Management or the
 
                                                     April 8, 1998 Prospectus 33
                                                      
<PAGE>
 
            Trust, and any counsel retained exclusively for their benefit;
            (vi) extraordinary expenses, including costs of litigation and in-
            demnification expenses; (vii) expenses, such as organizational ex-
            penses, which are capitalized in accordance with generally ac-
            cepted accounting principles; and (viii) any expenses allocated or
            allocable to a specific class of shares, which include servicing
            fees payable with respect to Class D shares, and may include cer-
            tain other expenses as permitted by the Trust's Multi-Class Plan
            adopted pursuant to Rule 18f-3 under the 1940 Act, subject to re-
            view and approval by the Trustees.
 
 
ADVISORY    The Funds feature fixed advisory and administrative fee rates. For
AND         providing investment advisory and administrative services to the
ADMINISTRA- Funds as described above, Pacific Investment Management receives
TIVE FEES   monthly fees from each Fund at an annual rate (i) based on the av-
            erage daily net assets of the Fund for advisory fees and, (ii) at-
            tributable in the aggregate to the Fund's Class D shares for ad-
            ministrative fees, as follows:
 
 
<TABLE>
<CAPTION>
                                                 ADVISORY
           FUND                                  FEE RATE
           ----------------------------------------------------
           <S>                                   <C>
           Strategic Balanced and StocksPLUS
            Funds                                .40%
           ----------------------------------------------------
           All other Funds                       .25%
 
 
 
<CAPTION>
                                                 ADMINISTRATIVE
           FUND                                  FEE RATE*
           ----------------------------------------------------
           <S>                                   <C>
           Foreign Bond Fund                     .70%
           ----------------------------------------------------
           Municipal Bond Fund                   .60%
           ----------------------------------------------------
           Short-Term, Low Duration and Total
            Return Funds                         .50%
           ----------------------------------------------------
           All other Funds                       .65%
</TABLE>
 
            * As described under "Fund Administrator," the administration
            agreement includes a plan adopted in conformity with Rule 12b-1
            which provides for the payment of up to .25% of the Administrative
            Fee Rate as reimbursement for expenses in respect of activities
            that may be deemed to be primarily intended to result in the sale
            of Class D shares. The "Annual Fund Operating Expenses" table on
            page 4 of this Prospectus shows the Administrative Fee Rate under
            two separate columns entitled "Administrative Fee" and "12b-1
            (Service) Fee."
 
               Both the investment advisory contract and administration agree-
            ment with respect to Class D shares of the Funds may be terminated
            by the Trustees at any time on 60 days' written notice. The in-
            vestment advisory contract may be terminated by Pacific Investment
            Management on 60 days' written notice. Following the expiration of
            the one-year period commencing with the effectiveness of the ad-
            ministration agreement, it may be terminated by Pacific Investment
            Management on 60 days' written notice. Following its initial two-
            year term, the investment advisory contract will continue from
            year to year if approved by the Trustees. Following its initial
            one-year term, the administration agreement with respect to Class
            D shares of the Funds will continue from year-to-year if approved
            by the Trustees.
 
PORTFOLIO   Pursuant to the advisory contract, the Advisor places orders for
TRANS-      the purchase and sale of portfolio investments for the Funds' ac-
ACTIONS     counts with brokers or dealers selected by it in its discretion.
            In effecting purchases and sales of portfolio securities for the
            account of the Funds, the Advisor will seek the best price and ex-
            ecution of the Funds' orders. In doing so, a Fund may pay higher
            commission rates than the lowest available when the Advisor be-
            lieves it is reasonable to do so in light of the value of the bro-
            kerage and research services provided by the broker effecting the
            transaction.
               The Advisor manages the Funds without regard generally to re-
            strictions on portfolio turnover, except those imposed on its
            ability to engage in short-term trading by provisions of the fed-
            eral tax laws. The use of certain derivative instruments with rel-
            atively short maturities may tend to exaggerate the portfolio
            turnover rate for some of the Funds. Trading in fixed income secu-
            rities does not generally involve the payment of brokerage commis-
            sions, but does involve indirect transaction costs. The use of
            futures contracts may involve the payment of commissions to
            futures commission merchants. The higher the rate of portfolio
            turnover of a Fund, the higher all these transaction costs borne
            by the Fund generally will be. The portfolio turnover rate for
            each Fund for which financial highlights are provided in this Pro-
            spectus is set forth under "Financial Highlights."
               Some securities considered for investments by the Funds may
            also be appropriate for other clients served by the Advisor. If a
            purchase or sale of securities consistent with the investment pol-
            icies of a Fund and one or more of these
 
34 PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
            clients served by the Advisor is considered at or about the same
            time, transactions in such securities will be allocated among the
            Fund and clients in a manner deemed fair and reasonable by the Ad-
            visor. The Advisor may aggregate orders for the Funds with simul-
            taneous transactions entered into on behalf of other clients of
            the Advisor so long as price and transaction expenses are averaged
            either for that transaction or for the day.
 
            Description of the Trust
 
CAPITALIZA- The Trust was organized as a Massachusetts business trust on Feb-
TION        ruary 19, 1987. The Board of Trustees may establish additional
            portfolios in the future. The capitalization of the Trust consists
            solely of an unlimited number of shares of beneficial interest
            with a par value of $0.0001 each. When issued, shares of the Trust
            are fully paid, non-assessable and freely transferable.

            Under Massachusetts law, shareholders could, under certain cir-
            cumstances, be held personally liable for the obligations of the
            Trust. However, the Declaration of Trust disclaims liability of
            the shareholders, Trustees or officers of the Trust for acts or
            obligations of the Trust, which are binding only on the assets and
            property of the Trust, and requires that notice of the disclaimer
            be given in each contract or obligation entered into or executed
            by the Trust or the Trustees. The Declaration of Trust also pro-
            vides for indemnification out of Trust property for all loss and
            expense of any shareholder held personally liable for the obliga-
            tions of the Trust. The risk of a shareholder incurring financial
            loss on account of shareholder liability is limited to circum-
            stances in which such disclaimer is inoperative or the Trust it-
            self is unable to meet its obligations, and thus should be consid-
            ered remote.
 
 
MULTIPLE    In addition to Class D shares, each Fund also offers up to five
CLASSES OF  additional classes of shares, Class A, Class B, Class C, Institu-
SHARES      tional Class and Administrative Class shares, through separate
            prospectuses. The other classes are subject to different sales
            charges and expense levels than Class D shares, which will affect
            performance accordingly. This Prospectus relates only to the Class
            D shares of the Funds. Unlike Class D shares, which may be pur-
            chased only through financial service firms, the other classes may
            be purchased directly from the Trust and/or the Distributor.
            Shareholders of a particular class may also receive additional
            services or services different from those received by the other
            classes. To obtain more information about the other classes of
            shares, please call the Distributor at 800-927-4648 (for Institu-
            tional and Administrative Classes) or 800-426-0107 (for Class A,
            Class B or Class C).
 
VOTING      Shareholders have the right to vote on the election of Trustees
            and on any and all matters on which the law or the Declaration of
            Trust states they may be entitled to vote. The Trust is not re-
            quired to hold regular annual meetings of Trust shareholders and
            does not intend to do so. Shareholders of a class of shares or
            Fund have separate voting rights with respect to matters that only
            affect that class or Fund. See "Other Information--Voting Rights"
            in the Statement of Additional Information.
               The Declaration of Trust provides that the holders of not less
            than two-thirds of the outstanding shares of the Trust may remove
            a person serving as Trustee either by declaration in writing or at
            a meeting called for such purpose. The Trustees are required to
            call a meeting for the purpose of considering the removal of a
            person serving as Trustee if requested in writing to do so by the
            holders of not less than 10% of the outstanding shares of the
            Trust.
               Shares entitle their holders to one vote per share (with pro-
            portionate voting for fractional shares). As of February 28, 1998,
            the following were shareholders of record of at least 25% of the
            outstanding voting securities of the indicated Fund: National Fi-
            nancial Services Corporation (New York, New York) with respect to
            the Real Return Bond Fund; Pacific Investment Management Company
            (Newport Beach, California) with respect to the Total Return Mort-
            gage and Municipal Bond Funds; and California Community Foundation
            (Los Angeles, California) with respect to the Strategic Balanced
            Fund. To the extent such shareholders are also the beneficial own-
            ers of those shares, they may be deemed to control (as that term
            is defined in the 1940 Act) the relevant Fund. As used in this
            Prospectus, the phrase "vote of a majority of the outstanding
            shares" of a Fund (or the Trust) means the vote of the lesser of:
            (1) 67% of the shares of the Fund (or the Trust) present at a
            meeting, if the holders of more than 50% of the outstanding shares
            are present in person or by proxy; or (2) more than 50% of the
            outstanding shares of the Fund (or the Trust).
 
                                                     April 8, 1998 Prospectus 35
                                                      
<PAGE>
 
            Appendix A
            Description of Duration
 
            Duration is a measure of the expected life of a fixed income secu-
            rity that was developed as a more precise alternative to the con-
            cept of "term to maturity." Traditionally, a fixed income
            security's "term to maturity" has been used as a proxy for the
            sensitivity of the security's price to changes in interest rates
            (which is the "interest rate risk" or "volatility" of the securi-
            ty). However, "term to maturity" measures only the time until a
            fixed income security provides its final payment, taking no ac-
            count of the pattern of the security's payments prior to maturity.
            In contrast, duration incorporates a bond's yield, coupon interest
            payments, final maturity and call features into one measure. Dura-
            tion management is one of the fundamental tools used by the Advi-
            sor.
               Duration is a measure of the expected life of a fixed income
            security on a present value basis. Duration takes the length of
            the time intervals between the present time and the time that the
            interest and principal payments are scheduled or, in the case of a
            callable bond, expected to be received, and weights them by the
            present values of the cash to be received at each future point in
            time. For any fixed income security with interest payments occur-
            ring prior to the payment of principal, duration is always less
            than maturity. In general, all other things being equal, the lower
            the stated or coupon rate of interest of a fixed income security,
            the longer the duration of the security; conversely, the higher
            the stated or coupon rate of interest of a fixed income security,
            the shorter the duration of the security.
               Futures, options and options on futures have durations which,
            in general, are closely related to the duration of the securities
            which underlie them. Holding long futures or call option positions
            (backed by a segregated account of cash and cash equivalents) will
            lengthen a Fund's duration by approximately the same amount that
            holding an equivalent amount of the underlying securities would.
               Short futures or put option positions have durations roughly
            equal to the negative duration of the securities that underlie
            these positions, and have the effect of reducing portfolio dura-
            tion by approximately the same amount that selling an equivalent
            amount of the underlying securities would.
               There are some situations where even the standard duration cal-
            culation does not properly reflect the interest rate exposure of a
            security. For example, floating and variable rate securities often
            have final maturities of ten or more years; however, their inter-
            est rate exposure corresponds to the frequency of the coupon re-
            set. For inflation-indexed bonds, duration is calculated on the
            basis of modified real duration, which measures price changes of
            inflation-indexed bonds on the basis of changes in real, rather
            than nominal, interest rates. Another example where the interest
            rate exposure is not properly captured by duration is the case of
            mortgage pass-through securities. The stated final maturity of
            such securities is generally 30 years, but current prepayment
            rates are more critical in determining the securities' interest
            rate exposure. Finally, the duration of a fixed income security
            may vary over time in response to changes in interest rates and
            other market factors. In these and other similar situations, the
            Advisor will use more sophisticated analytical techniques that in-
            corporate the anticipated economic life of a security into the de-
            termination of its interest rate exposure.
 
36 PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
            Appendix B
            Description of Securities Ratings
 
            Certain of the Funds make use of average portfolio credit quality
            standards to assist institutional investors whose own investment
            guidelines limit their investments accordingly. In determining a
            Fund's overall dollar-weighted average quality, unrated securities
            are treated as if rated, based on the Advisor's view of their com-
            parability to rated securities. A Fund's use of average quality
            criteria is intended to be a guide for those institutional invest-
            ors whose investment guidelines require that assets be invested
            according to comparable criteria. Reference to an overall average
            quality rating for a Fund does not mean that all securities held
            by the Fund will be rated in that category or higher. A Fund's in-
            vestments may range in quality from securities rated in the lowest
            category in which the Fund is permitted to invest to securities
            rated in the highest category (as rated by Moody's or S&P or, if
            unrated, determined by the Advisor to be of comparable quality).
            The percentage of a Fund's assets invested in securities in a par-
            ticular rating category will vary. Following is a description of
            Moody's and S&P's ratings applicable to fixed income securities.
 
 
MOODY'S     CORPORATE AND MUNICIPAL BOND RATINGS
INVESTORS      Aaa: Bonds which are rated Aaa are judged to be of the best
SERVICE,    quality. They carry the smallest degree of investment risk and are
INC.        generally referred to as "gilt edge." Interest payments are pro-
            tected by a large or by an exceptionally stable margin and princi-
            pal is secure. While the various protective elements are likely to
            change, such changes as can be visualized are most unlikely to im-
            pair the fundamentally strong position of such issues.
               Aa: Bonds which are rated Aa are judged to be of high quality
            by all standards. Together with the Aaa group they comprise what
            are generally known as high-grade bonds. They are rated lower than
            the best bonds because margins of protection may not be as large
            as in Aaa securities or fluctuation of protective elements may be
            of greater amplitude or there may be other elements present that
            make the long-term risks appear somewhat larger than with Aaa se-
            curities.
               A: Bonds which are rated A possess many favorable investment
            attributes and are to be considered as upper-medium-grade obliga-
            tions. Factors giving security to principal and interest are con-
            sidered adequate but elements may be present that suggest a sus-
            ceptibility to impairment sometime in the future.
               Baa: Bonds which are rated Baa are considered as medium-grade
            obligations (i.e., they are neither highly protected nor poorly
            secured). Interest payments and principal security appear adequate
            for the present but certain protective elements may be lacking or
            may be characteristically unreliable over any great length of
            time. Such bonds lack outstanding investment characteristics and
            in fact have speculative characteristics as well.
               Ba: Bonds which are rated Ba are judged to have speculative el-
            ements; their future cannot be considered as well-assured. Often
            the protection of interest and principal payments may be very mod-
            erate and thereby not well safeguarded during both good and bad
            times over the future. Uncertainty of position characterizes bonds
            in this class.
               B: Bonds which are rated B generally lack characteristics of a
            desirable investment. Assurance of interest and principal payments
            or of maintenance of other terms of the contract over any long pe-
            riod of time may be small.
               Caa: Bonds which are rated Caa are of poor standing. Such is-
            sues may be in default or there may be present elements of danger
            with respect to principal or interest.
               Ca: Bonds which are rated Ca represent obligations which are
            speculative in a high degree. Such issues are often in default or
            have other marked shortcomings.
               C: Bonds which are rated C are the lowest rated class of bonds
            and issues so rated can be regarded as having extremely poor pros-
            pects of ever attaining any real investment standing.
               Moody's applies numerical modifiers, 1, 2, and 3 in each ge-
            neric rating classified from Aa through B in its corporate bond
            rating system. The modifier 1 indicates that the security ranks in
            the higher end of its generic rating category; the modifier 2 in-
            dicates a mid-range ranking; and the modifier 3 indicates that the
            issue ranks in the lower end of its generic rating category.
 
                                                     April 8, 1998 Prospectus 37
<PAGE>
 
 
 
            CORPORATE SHORT-TERM DEBT RATINGS
            Moody's short-term debt ratings are opinions of the ability of is-
            suers to repay punctually senior debt obligations which have an
            original maturity not exceeding one year. Obligations relying upon
            support mechanisms such as letters of credit and bonds of indem-
            nity are excluded unless explicitly rated.
               Moody's employs the following three designations, all judged to
            be investment grade, to indicate the relative repayment ability of
            rated issuers:
               PRIME-1: Issuers rated Prime-1 (or supporting institutions)
            have a superior ability for repayment of senior short-term debt
            obligations. Prime-1 repayment ability will often be evidenced by
            many of the following characteristics: leading market positions in
            well-established industries; high rates of return on funds em-
            ployed; conservative capitalization structure with moderate reli-
            ance on debt and ample asset protection; broad margins in earnings
            coverage of fixed financial charges and high internal cash genera-
            tion; and well-established access to a range of financial markets
            and assured sources of alternate liquidity.
               PRIME-2: Issuers rated Prime-2 (or supporting institutions)
            have a strong ability for repayment of senior short-term debt ob-
            ligations. This will normally be evidenced by many of the charac-
            teristics cited above but to a lesser degree. Earnings trends and
            coverage ratios, while sound, may be more subject to variation.
            Capitalization characteristics, while still appropriate, may be
            more affected by external conditions. Ample alternate liquidity is
            maintained.
               PRIME-3: Issuers rated Prime-3 (or supporting institutions)
            have an acceptable ability for repayment of senior short-term ob-
            ligations. The effect of industry characteristics and market com-
            positions may be more pronounced. Variability in earnings and
            profitability may result in changes in the level of debt protec-
            tion measurements and may require relatively high financial lever-
            age. Adequate alternate liquidity is maintained.
               NOT PRIME: Issuers rated Not Prime do not fall within any of
            the Prime rating categories.
 
 
STANDARD &  CORPORATE AND MUNICIPAL BOND RATINGS
POOR'S
RATINGS     INVESTMENT GRADE
SERVICES       AAA: Debt rated AAA has the highest rating assigned by S&P. Ca-
            pacity to pay interest and repay principal is extremely strong.
               AA: Debt rated AA has a very strong capacity to pay interest
            and repay principal and differs from the highest rated issues only
            in small degree.
               A: Debt rated A has a strong capacity to pay interest and repay
            principal although it is somewhat more susceptible to the adverse
            effects of changes in circumstances and economic conditions than
            debt in higher rated categories.
               BBB: Debt rated BBB is regarded as having an adequate capacity
            to pay interest and repay principal. Whereas it normally exhibits
            adequate protection parameters, adverse economic conditions, or
            changing circumstances are more likely to lead to a weakened ca-
            pacity to pay interest and repay principal for debt in this cate-
            gory than in higher-rated categories.
 
            SPECULATIVE GRADE
            Debt rated BB, B, CCC, CC, and C is regarded as having predomi-
            nantly speculative characteristics with respect to capacity to pay
            interest and repay principal. BB indicates the least degree of
            speculation and C the highest. While such debt will likely have
            some quality and protective characteristics, these are outweighed
            by large uncertainties or major exposures to adverse conditions.
               BB: Debt rated BB has less near-term vulnerability to default
            than other speculative issues. However, it faces major ongoing un-
            certainties or exposure to adverse business, financial, or eco-
            nomic conditions which could lead to inadequate capacity to meet
            timely interest and principal payments. The BB rating category is
            also used for debt subordinated to senior debt that is assigned an
            actual or implied BBB- rating.
               B: Debt rated B has a greater vulnerability to default but cur-
            rently has the capacity to meet interest payments and principal
            repayments. Adverse business, financial, or economic conditions
            will likely impair capacity or willingness to
 
38 PIMCO Funds: Pacific Investment Management Series
<PAGE>
 
            pay interest and repay principal. The B rating category is also
            used for debt subordinated to senior debt that is assigned an ac-
            tual or implied BB or BB- rating.
               CCC: Debt rated CCC has a currently identifiable vulnerability
            to default and is dependent upon favorable business, financial,
            and economic conditions to meet timely payment of interest and re-
            payment of principal. In the event of adverse business, financial
            or economic conditions, it is not likely to have the capacity to
            pay interest and repay principal. The CCC rating category is also
            used for debt subordinated to senior debt that is assigned an ac-
            tual or implied B or B- rating.
               CC: The rating CC is typically applied to debt subordinated to
            senior debt that is assigned an actual or implied CCC rating.
               C: The rating C is typically applied to debt subordinated to
            senior debt that is assigned an actual or implied CCC- debt rat-
            ing. The C rating may be used to cover a situation where a bank-
            ruptcy petition has been filed, but debt service payments are con-
            tinued.
               CI: The rating CI is reserved for income bonds on which no in-
            terest is being paid.
               D: Debt rated D is in payment default. The D rating category is
            used when interest payments or principal payments are not made on
            the date due even if the applicable grace period has not expired,
            unless S&P believes that such payments will be made during such
            grace period. The D rating will also be used upon the filing of a
            bankruptcy petition if debt service payments are jeopardized.
               Plus (+) or Minus (-): The ratings from AA to CCC may be modi-
            fied by the addition of a plus or minus sign to show relative
            standing within the major rating categories.
               Provisional ratings: The letter "p" indicates that the rating
            is provisional. A provisional rating assumes the successful com-
            pletion of the project being financed by the debt being rated and
            indicates that payment of debt service requirements is largely or
            entirely dependent upon the successful and timely completion of
            the project. This rating, however, while addressing credit quality
            subsequent to completion of the project, makes no comment on the
            likelihood of, or the risk of default upon failure of, such com-
            pletion. The investor should exercise his own judgment with re-
            spect to such likelihood and risk.
               r: The "r" is attached to highlight derivative, hybrid, and
            certain other obligations that S&P believes may experience high
            volatility or high variability in expected returns due to non-
            credit risks. Examples of such obligations are: securities whose
            principal or interest return is indexed to equities, commodities,
            or currencies; certain swaps and options; and interest only and
            principal only mortgage securities.
               The absence of an "r" symbol should not be taken as an indica-
            tion that an obligation will exhibit no volatility or variability
            in total return.
               N.R.: Not rated.
               Debt obligations of issuers outside the United States and its
            territories are rated on the same basis as domestic corporate and
            municipal issues. The ratings measure the creditworthiness of the
            obligor but do not take into account currency exchange and related
            uncertainties.
 
            COMMERCIAL PAPER RATING DEFINITIONS
            An S&P commercial paper rating is a current assessment of the
            likelihood of timely payment of debt having an original maturity
            of no more than 365 days. Ratings are graded into several catego-
            ries, ranging from A for the highest quality obligations to D for
            the lowest. These categories are as follows:
               A-1: This highest category indicates that the degree of safety
            regarding timely payment is strong. Those issues determined to
            possess extremely strong safety characteristics are denoted with a
            plus sign (+) designation.
               A-2: Capacity for timely payment on issues with this designa-
            tion is satisfactory. However, the relative degree of safety is
            not as high as for issues designated A-1.
               A-3: Issues carrying this designation have adequate capacity
            for timely payment. They are, however, more vulnerable to the ad-
            verse effects of changes in circumstances than obligations carry-
            ing the higher designations.
 
                                                     April 8, 1998 Prospectus 39
                                                      
<PAGE>
 
               B: Issues rated B are regarded as having only speculative ca-
            pacity for timely payment.
               C: This rating is assigned to short-term debt obligations with
            a doubtful capacity for payment.
               D: Debt rated D is in payment default. The D rating category is
            used when interest payments or principal payments are not made on
            the date due, even if the applicable grace period has not expired,
            unless S&P believes that such payments will be made during such
            grace period.
               A commercial paper rating is not a recommendation to purchase,
            sell or hold a security inasmuch as it does not comment as to mar-
            ket price or suitability for a particular investor. The ratings
            are based on current information furnished to S&P by the issuer or
            obtained from other sources it considers reliable. S&P does not
            perform an audit in connection with any rating and may, on occa-
            sion, rely on unaudited financial information. The ratings may be
            changed, suspended, or withdrawn as a result of changes in or un-
            availability of such information.
 
 
40 PIMCO Funds: Pacific Investment Management Series
<PAGE>
<TABLE> 
 <CAPTION> 
<C>                 <S>
                    ----------------------------------------------------------------------------------------------
PIMCO Funds:        INVESTMENT ADVISOR AND ADMINISTRATOR                      
Pacific Investment                                                            
Management Series   Pacific Investment Management Company, 840 Newport Center Drive, Suite 360,
                    Newport Beach, CA 92660
                    ----------------------------------------------------------------------------------------------
                    DISTRIBUTOR                                               
                                                                              
                    PIMCO Funds Distributors LLC, 2187 Atlantic Street, Stamford, CT 06902  
                    ----------------------------------------------------------------------------------------------
                    CUSTODIAN                                                
                                                                             
                    Investors Fiduciary Trust Company, 801 Pennsylvania, Kansas City, MO 64105      
                    ----------------------------------------------------------------------------------------------
                    SHAREHOLDER SERVICING AGENT AND TRANSFER AGENT          
                                                                            
                    Shareholder Services, Inc., P.O. Box 5866, Denver, CO 80217               
                    ----------------------------------------------------------------------------------------------
                    INDEPENDENT ACCOUNTANTS
                                     
                    Price Waterhouse LLP, 1055 Broadway, Kansas City, MO 64105                      
                    ----------------------------------------------------------------------------------------------
                    LEGAL COUNSEL     
                                      
                    Dechert Price & Rhoads, 1775 Eye Street N.W., Washington, D.C. 20006-2401              
                    ----------------------------------------------------------------------------------------------
                    For further information about the PIMCO Funds, call 1-888-87-PIMCO or vist our Web site
                    at http://www.pimcofunds.com.
</TABLE> 


© 2022 IncJournal is not affiliated with or endorsed by the U.S. Securities and Exchange Commission