<PAGE>   1
                                                                       Ex 3.1(a)

                                                               STATE OF DELAWARE
                                                              SECRETARY OF STATE
                                                        DIVISION OF CORPORATIONS
                                                       FILED 11:30 AM 12/30/1996
                                                             960387324 - 2292039




              CERTIFICATE OF DESIGNATIONS, PREFERENCES AND RIGHTS
                  OF 5% CUMULATIVE CONVERTIBLE PREFERRED STOCK
                          (Par Value $0.01 Per Share)

                                       of

                             THE JOHN NUVEEN COMPANY

             Pursuant to Section 151 of the General Corporation Law
                            of the State of Delaware


         The undersigned, Anthony T. Dean, President and Chief Operating
Officer of THE JOHN NUVEEN COMPANY, a corporation organized and existing under
the General Corporation Law of the State of Delaware (the "Corporation"), in
accordance with the provisions of Section 103 thereof, DOES HEREBY CERTIFY:

         That in accordance with the provisions of Section 151 of the General
Corporation Law of the State of Delaware and pursuant to Article Fifth of the
Certificate of Incorporation of the Corporation, the Board of Directors of the
Corporation is authorized to issue from time to time shares of Preferred Stock,
par value $0.01 per share, in one or more series and has authorized the
creation of the series of Preferred Stock hereinafter provided for and has
established the voting rights thereof and has adopted the following resolution
creating a series of 1,800,000 shares of Preferred Stock, par value $0.01 per
share, designated as 5% Cumulative Convertible Preferred Stock, as follows:

         RESOLVED, that pursuant to the authority expressly vested in the Board
of Directors of this Corporation in accordance with the provisions of its
Certificate of Incorporation, a series of Preferred Stock of the corporation,
par value $0.01 per share, be and it hereby is, created, and that the
designation and amount thereof and the voting powers, preferences and relative,
participating, optional and other special rights of the shares of such series,
and the qualifications, limitations or restrictions thereof are as follows:

         Section 1.  Number of Shares and Designation.  One million eight
hundred thousand (1,800,000) shares of the Preferred Stock, par value $0.01 per
share, of the Corporation are hereby constituted as a series of the Preferred
Stock designated as 5% Cumulative Convertible Preferred Stock (the "Convertible
Preferred Stock").

<PAGE>   2
         Section 2. Definitions. For purposes of the Convertible Preferred
Stock, the following terms shall have the meanings indicated:


         "Board of Directors" shall mean the board of directors of the
Corporation or any committee authorized by such board of directors to perform
any of its responsibilities with respect to the Convertible Preferred Stock.


         "Business Day" shall mean any day other then a Saturday, Sunday or a
day on which state or federally chartered banking institutions in Chicago,
Illinois or New York, New York are not required to be open.


         "Class A Common Stock" shall mean the Class A Common Stock of the
Corporation, par value $0.01 per share.


         "Class B Common Stock" shall mean the Class B Common Stock of the
Corporation, par value $0.01 per share.


         "Constituent Person" shall have the meaning set forth in paragraph (E)
of Section 7 hereof.


         "Conversion Price" shall mean the conversion price per share of Class
A Common Stock for which the Convertible Preferred Stock is convertible, as such
Conversion Price may be adjusted pursuant to Section 7 hereof. The initial
Conversion Price will be $27.28.


         "Convertible Preferred Stock" shall have the meaning set forth in
Section 1 hereof.


         "Current Market Price" of publicly traded shares of Class A Common
Stock or any other class of capital stock or other security of the Corporation
or any other issuer for any day shall mean the last reported sales price,
regular way on such day or, if no sale takes place on such day, the average
regular way, in either case as reported on the New York Stock Exchange Composite
Tape or, if such security is not listed or admitted for trading on the New York
Stock Exchange ("NYSE"), on the principal national securities exchange on which
such security is listed or admitted for trading or, if not listed or admitted
for trading on any national securities exchange, on the Nasdaq Stock Market or,
if such security is not quoted on the Nasdaq Stock Market, the average of the
closing bid and asked prices on such day in the over-the-counter market as
reported by the National Association of Securities Dealers, Inc. Automated
Quotations System ("NASDAQ") or, if bid and asked prices for such security on
such day shall not have been


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reported through NASDAQ, the average of the bid and asked prices on such day as
furnished by any NYSE member firm regularly making a market in such security
selected for such purpose by the Board of Directors.

        "Dividend Payment Date" shall mean the first day of the first month of
each quarterly period in each year, commencing on the first day of the first
full month following the Issue Date; provided, however, that if any Dividend
Payment Date falls on any day other than a Business Day, the dividend payment
due on such Dividend Payment Date shall be paid on the Business Day immediately
following such Dividend Payment Date.

        "Dividend Periods" shall mean quarterly dividend periods commencing on
each Dividend Payment Date of each year and ending on and including the day
preceding the first day of the next succeeding Dividend Period (other than the
initial Dividend Period, which shall commence on the Issue Date and end on and
include the day preceding the first Dividend Payment Date thereafter).

        "Fair Market Value" shall mean the average of the daily Current Market
Prices of a share of Class A Common Stock during the five (5)
consecutive Trading Days selected by the Corporation commencing not more than
20 Trading Days before, and ending not later than, the earlier of the day in
question and the day before the "ex" date with respect to the issuance or
distribution requiring such computation. The term "'ex' date", when used with
respect to any issuance or distribution, means the first day on which the Class
A Common Stock trades regular way, without the right to receive such issuance
or distribution, on the exchange or in the market, as the case may be, used to
determine that day's Current Market Price.

        "Issue Date" shall mean the first date on which shares of Convertible
Preferred Stock are issued.

        "Junior Stock" shall mean the Class A Common Stock, the Class B Common
Stock and any other class or series of stock of the Corporation over which the
Convertible Preferred Stock has preference or priority in the payment of
dividends or in the distribution of assets on any liquidation, dissolution or
winding up of the Corporation.

        "Liquidation Preference" shall have the meaning set forth in paragraph
(A) of Section 4 hereof.

        "non-electing share" shall have the meaning set forth in paragraph (E)
of Section 7 hereof.



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        "Parity Stock" shall mean any other class or series of stock of the
Corporation which ranks on a parity with the Convertible Preferred Stock as to
payment of dividends or in the distribution of the assets on any liquidation,
dissolution or winding up of the Corporation.

        "Person" shall mean any individual, firm, partnership, corporation or
other entity, and shall include any successor (by merger or otherwise) of such
entity.

        "Redemption Date" shall have the meaning set forth in paragraph (C) of
Section 5 hereof.

        "Rights" shall mean rights of the Corporation to purchase any capital
stock of the Corporation under any shareholder rights plan or plans adopted by
the Corporation.

        "Securities" shall have the meaning set forth in paragraph (D)(iii) of
Section 7 hereof.

        "set apart for payment" shall be deemed to include, without any action
other than the following, the recording by the Corporation in its accounting
ledgers of any accounting or bookkeeping entry which indicates, pursuant to a
declaration of dividends or other distribution by the Board of Directors, the
allocation of funds to be so paid on any series or class of capital stock of
the Corporation; provided, however, that if any funds for any class or series
of Junior Stock or any Parity Stock are placed in a separate account of the
Corporation or delivered to a disbursing, paying or other similar agent, then
during the period that any such funds remain in such account or with such
agent, "set apart for payment" with respect to the Convertible Preferred Stock
shall mean placing such funds in a separate account or delivering such funds to
a disbursing, paying or other similar agent.

        "Stated Value" shall have the meaning set forth in paragraph (A) of
Section 4 hereof.

        "Trading Day" shall mean any day on which the securities in question
are traded on the NYSE, or if such securities are not listed or admitted for
trading on the NYSE, on the principal national securities exchange on which
such securities are listed or admitted, or if not listed or admitted for
trading on any national securities exchange, on the Nasdaq Stock Market, or if
such securities are not quoted on the Nasdaq Stock Market, in the applicable
securities market in which the securities are traded.



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         "Transaction" shall have the meaning set forth in paragraph (E) of
Section 7 hereof.

         "Transfer Agent" shall mean the Secretary of the Corporation or such
other agent or agents of the Corporation as may be designated by the Board of
Directors as the transfer agent for the Convertible Preferred Stock.

         Section 3. Dividends. (A) The holders of shares of the Convertible
Preferred Stock shall be entitled to receive, when, as and if declared by the
Board of Directors out of assets legally available for that purpose, dividends
payable in cash at a rate per Dividend Period equal to (x) one-fourth (1/4) of
5% of the Stated Value per share of Convertible Preferred Stock or, if greater
than the rate specified in clause (x) and if the regular quarterly dividend
rate last declared during the relevant Dividend Period in respect of the Class
A Common Stock (the "Common Rate") is greater than two times the regular
quarterly dividend rate last declared prior to the Issue Date in respect of the
Class A Common Stock, then (y) the Common Rate multiplied by the number of
shares of Class A Common Stock into which the Convertible Preferred Stock is
then convertible. Such dividends shall be cumulative from the Issue Date,
whether or not in any Dividend Period or Dividend Periods there shall be assets
of the Corporation legally available for the payment of such dividends, and
shall be payable quarterly, when, as and if declared by the Board of Directors,
in arrears on Dividend Payment Dates, commencing on the first Dividend Payment
Date following the Issue Date. Each such dividend shall be payable in arrears
to the holders of record of shares of the Convertible Preferred Stock, as they
appear on the stock records of the Corporation at the close of business on such
record dates, which shall not be more than 60 days nor less than 10 days
preceding the payment dates thereof, as shall be fixed by the Board of
Directors. Accrued and unpaid dividends for any past Dividend Periods may be
declared and paid at any time, without reference to any Dividend Payment Date,
to holders of record on such date, not exceeding 45 days preceding the payment
date thereof, as may be fixed by the Board of Directors.

         (B) The amount of dividends payable for each full Dividend Period for
the Convertible Preferred Stock shall be equal to the full per Dividend Period
dividend rate. The amount of dividends payable for the initial Dividend Period,
or any other period shorter or longer than a full Dividend Period, on the
Convertible Preferred Stock shall be computed on the basis of twelve 30-day
months and a 360-day year. Holders of shares of Convertible Preferred Stock
shall not be entitled to any dividends, whether payable in cash, property or
stock, in


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excess of cumulative dividends, as herein provided, on the Convertible
Preferred Stock. No interest, or sum of money in lieu of interest, shall be
payable in respect of any dividend payment or payments on the Convertible
Preferred Stock that may be in arrears.

         (C) So long as any shares of the Convertible Preferred Stock are
outstanding, no dividends, except as described in the next succeeding sentence,
shall be declared or paid or set apart for payment on any Parity Stock for any
period unless full cumulative dividends have been or contemporaneously are
declared and paid or declared and a sum sufficient for the payment thereof set
apart for such payment on the Convertible Preferred Stock for all Dividend
Periods terminating on or prior to the date of payment of the dividend on such
Parity Stock. When dividends are not paid in full or a sum sufficient for such
payment is not set apart, as aforesaid, all dividends declared upon shares of
the Convertible Preferred Stock and all dividends declared upon any Parity
Stock shall be declared ratably in proportion to the respective amounts of
dividends accumulated and unpaid on the Convertible Preferred Stock and
accumulated and unpaid on such Parity Stock.

         (D) So long as any shares of the Convertible Preferred Stock are
outstanding, no dividends (other than (i) the Rights and (ii) dividends or
distributions paid in shares of, or options, warrants or rights to subscribe
for or purchase shares of, Junior Stock) shall be declared or paid or set apart
for payment or other distribution declared or made upon Junior Stock, nor shall
any Junior Stock or any Parity Stock be redeemed, purchased or otherwise
acquired (other than a redemption, purchase or other acquisition of shares of
Common Stock made for purposes of an employee incentive or benefit plan of the
Corporation or any subsidiary) for any consideration (or any moneys be paid to
or made available for a sinking fund for the redemption of any shares of any
such stock) by the Corporation, directly or indirectly (except by conversion
into or exchange for Junior Stock), unless in each case all accrued and unpaid
dividends on all outstanding shares of the Convertible Preferred Stock and any
Parity Stock shall have been paid or funds have been set apart for payment of
such dividends for all past Dividend Periods with respect to the Convertible
Preferred Stock and all past dividend periods with respect to such Parity Stock.


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Section 4. Payments upon Liquidation.

     (A) In the event of any voluntary or involuntary liquidation, dissolution
or winding up of the Corporation, before any payment or distribution of the
assets of the Corporation (whether capital or surplus) shall be made to or set
apart for the holders of Junior Stock, the holders of the shares of Convertible
Preferred Stock shall be entitled to receive Twenty-Five Dollars ($25) per share
of Convertible Preferred Stock (the "Stated Value") plus an amount per share of
Convertible Preferred Stock equal to all dividends (whether or not earned or
declared) accrued and unpaid thereon to the date of final distribution to such
holders (the "Liquidation Preference"); but such holders shall not be entitled
to any further payment. If, upon any liquidation, dissolution or winding up of
the Corporation, the assets of the Corporation, or proceeds thereof,
distributable among the holders of the shares of Convertible Preferred Stock
shall be insufficient to pay in full the Liquidation Preference and the
liquidation preference on all other shares of any Parity Stock, then such
assets, or the proceeds thereof, shall be distributed among the holders of
shares of Convertible Preferred Stock and any such other Parity Stock ratably in
accordance with the respective amounts that would be payable on such shares of
Convertible Preferred Stock and any such other stock if all amounts payable
thereon were paid in full. For the purposes of this Section 4, (i) a
consolidation, merger or business combination of the Corporation with or into
one or more corporations, or (ii) a sale or transfer of all or substantially all
of the Corporation's assets, shall not be deemed to be a liquidation,
dissolution or winding up, voluntary or involuntary, or the Corporation.

     (B) Subject to the rights of the holders of Parity Stock, after payment
shall have been made to the holders of the Convertible Preferred Stock, and to
the fullest extent provided in this Section 4, any other series or class or
classes of Junior Stock shall, subject to the respective terms and provisions
(if any) applying thereto, be entitled to receive any and all assets remaining
to be paid or distributed, and the holders of the Convertible Preferred Stock
shall not be entitled to share therein.

     Section 5. Redemption at the Option of the Corporation; Mandatory
Redemption.

     (A) The shares of Convertible Preferred Stock shall be redeemable
at the option of the Corporation, in whole, or, from time to time, in part, out
of funds legally available for such purpose, at any time on or after the fourth
anniversary of the Issue Date, and shall in any event be redeemed in whole by
the Corporation as of the





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<PAGE>   8
tenth such anniversary of the Issue Date, in each case, at a redemption price
of $25.00 per share of Convertible Preferred Stock, plus an amount equal to all
dividends accrued and unpaid on the shares of Convertible Preferred Stock up to
the date fixed for the redemption, upon giving notice as provided hereinbelow.

         (B) If fewer than all of the outstanding shares of Convertible
Preferred Stock are to be redeemed, the number of shares to be redeemed shall be
determined by the Board of Directors and the shares to be redeemed shall be
determined pro rata or by lot or in such other manner and subject to such
regulations as the Board of Directors in its sole discretion shall prescribe.

         (C) At least 30 days, but not more than 60 days, prior to the date
fixed for the redemption of shares of Convertible Preferred Stock, a written
notice shall be mailed in a postage prepaid envelope to each holder of record of
the shares of Convertible Preferred Stock to be redeemed, addressed to such
holder at his or her post office address as shown on the records of the
Corporation, notifying such holder of the election of the Corporation to redeem
such shares, stating the date fixed for redemption thereof (the "Redemption
Date"), and calling upon such holder to surrender to the Corporation, on the
Redemption Date at the place designated in such notice, his or her certificate
or certificates representing the number of shares specified in such notice of
redemption. On or after the Redemption Date, such holder of shares of
Convertible Preferred Stock to be redeemed shall present and surrender his or
her certificate or certificates for such shares to the Corporation at the place
designated in such notice and thereupon the redemption price of such shares
(including an amount equal to all accrued and unpaid dividends up to the
Redemption Date) shall be paid to the order of the person whose name appears on
such certificate or certificates as the owner thereof and each surrendered
certificate shall be cancelled. In case less than all the shares represented by
any such certificates are redeemed, a new certificate shall be issued
representing the unredeemed shares.

         From and after the Redemption Date (unless the Corporation defaults in
payment of the redemption price), all dividends on the shares of Convertible
Preferred Stock designated for redemption in such notice shall cease to accrue,
and all rights of the holders thereof as stockholders of the Corporation, except
the right to receive the redemption price of such shares (including an amount
equal to all accrued and unpaid dividends up to the Redemption Date) upon the
surrender of certificates representing the same, shall cease and terminate and


                                      -8-

<PAGE>   9
such shares shall not thereafter be transferred (except with the consent of the
Corporation) on the books of the Corporation, and such shares shall not be
deemed to be outstanding for any purpose whatsoever; provided however, in the
case of the Redemption Date falling after a dividend payment record date and
prior to the related Dividend Payment Date, the holders of Convertible
Preferred Stock at the close of business on such record date will be entitled
to receive the dividend payable on such shares on the corresponding Dividend
Payment Date, notwithstanding the redemption of such shares following such
dividend payment record date.

         At its election, the Corporation, prior to the Redemption Date, may
deposit the redemption price (including an amount equal to all accrued and
unpaid dividends up to the Redemption Date) of the shares of Convertible
Preferred Stock so called for redemption in trust for the holders thereof with a
bank or trust company (having a capital surplus and undivided profits
aggregating not less than $50,000,000) in the Borough of Manhattan, City and
State of New York, or in any other city in which the Corporation at the time
shall maintain a transfer agency with respect to such shares, in which case the
aforesaid notice to holders of shares of Convertible Preferred Stock to be
redeemed shall (i) state the date of such deposit, (ii) shall specify the office
of such bank or trust company as the place of payment of the redemption price
and (iii) shall call upon such holders to surrender the certificates
representing such shares at such place on or after the date fixed in
such redemption notice (which shall not be later than the Redemption Date)
against payment of the redemption price (including an amount equal to all
accrued and unpaid dividends up to the Redemption Date). Any interest accrued on
such funds shall be paid to the Corporation from time to time. Any moneys so
deposited which shall remain unclaimed by the holders of such shares of
Convertible Preferred Stock at the end of two years after the Redemption Date
shall be returned by such bank or trust company to the Corporation.

         If a notice of redemption has been given pursuant to this Section 5
and any holder of shares of Convertible Preferred Stock shall, prior to the
close of business on the day preceding the Redemption Date, give written notice
to the Corporation pursuant to Section 7 below of the conversion of any or all
of the shares to be redeemed held by such holder (accompanied by a certificate
or certificates for such shares, duly endorsed or assigned to the Corporation,
and any necessary transfer tax payment, as required by Section 7 below), then
such redemption shall not become effective as to such shares to


                                      -9-


<PAGE>   10
be converted, such conversion shall become effective as provided in Section 7
below, and any moneys set aside by the Corporation for the redemption of such
shares of converted Convertible Preferred Stock shall revert to the general
funds of the Corporation.


         Section 6.  Shares to Be Retired. All shares of Convertible Preferred
Stock which shall have been issued and reacquired in any manner by the
Corporation (excluding, until the Corporation elects to retire them, shares
which are held as treasury shares) shall be restored to the status of authorized
but unissued shares of Preferred Stock, without designation as to series.


         Section 7.  Conversion. Holders of shares of Convertible Preferred
Stock shall have the right to convert all or a portion of such shares into
shares of Class A Common Stock, as follows:


         (A)  Subject to and upon compliance with the provisions of this Section
7, a holder of shares of Convertible Preferred Stock shall have the right, at
his or her option, at any time or from time to time after the second anniversary
of the Issue Date, to convert such shares into the number of fully paid and
nonassessable shares of Class A Common Stock obtained by dividing the aggregate
Stated Value of such shares by the Conversion Price (as in effect on the date
provided for in the last paragraph of paragraph (B) of this Section 7) by
surrendering such shares to be converted, such surrender to be made in the
manner provided in paragraph (B) of this Section 7; provided, however, that the
right to convert shares called for redemption pursuant to Section 5 shall
terminate at the close of business on the date preceding the Redemption Date,
unless the Corporation shall default in making payment of the cash payable upon
such redemption under Section 5 hereof. Certificates will be issued for the
remaining shares of Convertible Preferred Stock in any case in which fewer than
all of the shares of Convertible Preferred Stock represented by a certificate
are converted.


         (B)  In order to exercise the conversion right, the holder of shares of
Convertible Preferred Stock to be converted shall surrender the certificate or
certificates representing such shares, duly endorsed or assigned to the
Corporation or in blank, at the office of the Transfer Agent in the Borough of
Manhattan, City of New York, accompanied by written notice to the Corporation
that the holder thereof elects to convert Convertible Preferred Stock. Unless
the shares issuable on conversion are to be issued in the same name as the name
in which such share of Convertible Preferred Stock is registered, each


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share surrendered for conversion shall be accompanied by instruments of
transfer, in the form satisfactory to the Corporation, duly executed by the
holder or such holder's duly authorized attorney and an amount sufficient to pay
any transfer or similar tax (or evidence reasonably satisfactory to the
Corporation demonstrating that such taxes have been paid).

         Holders of shares of Convertible Preferred Stock at the close of
business on a dividend payment record date shall be entitled to receive the
dividend payable on such shares on the corresponding Dividend Payment Date
notwithstanding the conversion thereof following such dividend payment record
date and prior to such Dividend Payment Date. However, shares of Convertible
Preferred Stock surrendered for conversion during the period between the close
of business on any dividend payment record date and the opening of business on
the corresponding Dividend Payment Date (except shares converted after the
issuance of a notice of redemption with respect to a Redemption Date during such
period, which shall be entitled to the benefit of such dividend on the Dividend
Payment Date) must be accompanied by payment of an amount equal to the dividend
payable on such shares on such Dividend Payment Date. A holder of shares of
Convertible Preferred Stock on a dividend payment record date who (or whose
transferee) tenders any such shares for conversion into shares of Class A Common
Stock on such Dividend Payment Date will receive the dividend payable by the
Corporation on such shares of Convertible Preferred Stock on such date, and the
converting holder need not include payment of the amount of such dividend upon
surrender of shares Convertible Preferred Stock for conversion. Except as
provided above, the Corporation shall make no payment or allowance for unpaid
dividends, whether or not in arrears, on converted shares or for dividends on
the shares of Class A Common Stock issued upon such conversion.

         As promptly as practicable after the surrender of certificates for
shares of Convertible Preferred Stock as aforesaid, the Corporation shall issue
and deliver at such office to such holder, or on his or her written order, a
certificate or certificates for the number of full shares of Common Stock
issuable upon the conversion of such shares in accordance with the provisions of
this Section 7, and any fractional interest in respect of a share of Class A
Common Stock arising upon such conversion shall be settled as provided in
paragraph (C) of this Section 7.

         Each conversion shall be deemed to have been effected immediately prior
to the close of business on the date on which the certificates for shares of
Convertible Preferred Stock shall have been surrendered and such notice (and if
applicable,


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<PAGE>   12
payment of an amount equal to the dividend payable on such shares) received by
the Corporation as aforesaid, and the person or persons in whose name or names
any certificate or certificates for shares of Class A Common Stock shall be
issuable upon such conversion shall be deemed to have become the holder or
holders of record of the shares represented thereby at such time on such date
and such conversion shall be at the Conversion Price in effect at such time on
such date, unless the stock transfer books of the Corporation shall be closed
on that date, in which event such person or persons shall be deemed to have
become such holder or holders of record at the close of business on the next
succeeding day on which such stock transfer books are open, but such conversion
shall be at the Conversion Price in effect on the date upon which such shares
shall have been surrendered and such notice received by the Corporation.

         (C) No fractional shares or scrip representing fractions of shares
of Class A Common Stock shall be issued upon conversion of the Convertible
Preferred Stock. Instead of any fractional interest in a share of Class A
Common Stock that would otherwise be deliverable upon the conversion of a share
of Convertible Preferred Stock, the Corporation shall pay to the holder of such
share an amount in cash based upon the Current Market Price of Class A Common
Stock on the Trading Day immediately preceding the date of conversion. If more
than one share shall be surrendered for conversion at one time by the same
holder, the number of full shares of Class A Common Stock issuable upon
conversion thereof shall be computed on the basis of the aggregate number of
shares of Convertible Preferred Stock so surrendered.

         (D) The Conversion Price shall be adjusted from time to time as
follows:

          (i) If the Corporation shall after the Issue Date (A) pay a dividend
     or make a distribution on its capital stock in shares of its Class A Common
     Stock, (B) subdivide its outstanding Class A Common Stock into a greater
     number of shares, (C) combine its outstanding Class A Common Stock into a
     smaller number of shares or (D) issue any shares of capital stock by
     reclassification of its Class A Common Stock, the Conversion Price in
     effect at the opening of business on the day next following the date fixed
     for the determination of stockholders entitled to receive such dividend or
     distribution or at the opening of business on the day next following the
     day on which such subdivision, combination or reclassification becomes
     effective, as the case may be,


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<PAGE>   13
     shall be adjusted so that the holder of any share of Convertible Preferred
     Stock thereafter surrendered for conversion shall be entitled to receive
     the number of shares of Class A Common Stock that such holder would have
     owned or have been entitled to receive after the happening of any of the
     events described above had such share been converted immediately prior to
     the record date in the case of a dividend or distribution or the effective
     date in the case of a subdivision, combination or reclassification. An
     adjustment made pursuant to this subparagraph (i) shall become effective
     immediately after the opening of business on the day next following the
     record date (except as provided in paragraph (H) below) in the case of a
     dividend or distribution and shall become effective on the day next
     following the effective date in the case of a subdivision, combination or
     reclassification.

          (ii) If the Corporation shall issue after the Issue Date rights or
     warrants (in each case, other than the Rights) to all holders of Class A
     Common Stock entitling them (for a period expiring within 45 days after
     the record date mentioned below) to subscribe for or purchase Class A
     Common Stock or Securities which are convertible into Class A Common Stock
     at a price per share less than the Fair Market Value per share of Class A
     Common Stock on the record date for the determination of stockholders
     entitled to receive such rights or warrants, then the Conversion Price in
     effect at the opening of business on the day next following such record
     date shall be adjusted to equal the price determined by multiplying (I)
     the Conversion Price in effect immediately prior to the opening of
     business on the day next following the date fixed for such determination
     by (II) a fraction, the numerator of which shall be the sum of (A) the
     number of shares of Class A Common Stock outstanding on the close of
     business on the date fixed for such determination and (B) the number of
     shares that the aggregate proceeds to the Corporation from the exercise of
     such rights or warrants for Class A Common Stock would purchase at such
     Fair Market Value, and the denominator of which shall be the sum of (A)
     the number of shares of Class A Common Stock outstanding on the close of
     business on the date fixed for such determination and (B) the number of
     additional shares of Class A Common Stock offered for subscription or
     purchase pursuant to such rights or warrants. Such adjustment shall become
     effective immediately after the opening of business on the day next
     following such record date (except as provided in paragraph (H) below). In
     determining whether any rights or warrants entitle the holders of Class A
     Common Stock to subscribe for or

                                      -13-
<PAGE>   14


purchase shares of Class A Common Stock at less than such Fair market Value,
there shall be taken into account any consideration received by the Corporation
upon issuance and upon exercise of such rights or warrants, the value of such
consideration, if other than cash, to be determined by valuation of the Board
of Directors.

     (iii) If the Corporation shall distribute to all holders of its Class A
Common Stock any shares of capital stock of the Corporation (other than Class A
Common Stock) or evidence of its indebtedness or assets (excluding any cash
dividends or distributions paid from profits or surplus of the Corporation or
referred to in subparagraph (i) above or any stocks, securities or other
property received pursuant to paragraph 7(E) below) or rights of warrants (in
each case, other than the Rights) to subscribe for or purchase any of its
securities (excluding those rights and warrants issued to all holders of Class
A Common Stock entitling them for a period expiring within 45 days after the
record date referred to in subparagraph (ii) above to subscribe for or purchase
Class A Common Stock, which rights and warrants are referred to in and treated
under subparagraph (ii) above) (any of the foregoing being hereinafter in this
subparagraph (iii) called the "Securities"), then in each such case the
Conversion Price shall be adjusted so that it shall equal the price determined
by multiplying (I) the Conversion Price in effect immediately prior to the
close of business on the date fixed for the determination of stockholders
entitled to receive such distribution by (II) a fraction, the numerator of
which shall be the Fair Market Value per share of the Class A Common Stock on
the record date mentioned below less the then fair market value (as determined
by the Board of Directors, whose determination shall be conclusive) of the
portion of the capital stock or assets or evidences of indebtedness so
distributed or of such rights or warrants applicable to one share of Class A
Common Stock, and the denominator of which shall be the Fair Market Value per
share of the Class A Common Stock on the record date mentioned below. Such
adjustment shall become effective immediately at the opening of business on the
Business Day next following (except as provided in paragraph (H) below) the
record date for the determination of shareholders entitled to receive such
distribution. For the purposes of this subparagraph (iii), the distribution of
a Security, which is distributed not only to the holders of the Class A Common
Stock on the date fixed for the determination of stockholders entitled to such
distribution of such Security, but also is distributed to the holders of the



                                      -14-
<PAGE>   15
     Convertible Preferred Stock (assuming for purposes of this subparagraph
     (iii) that such shares of Convertible Preferred Stock have been converted)
     or reserved for distribution with each share of Class A Common Stock
     delivered to a person converting a share of Convertible Preferred Stock
     after such determination date, shall not require an adjustment of the
     Conversion Price pursuant to this subparagraph (iii); provided that on the
     date, if any, on which a Person converting a share of Convertible Preferred
     Stock would no longer be entitled to receive such Security with a share of
     Class A Common Stock (other than as a result of the termination of all such
     Securities), a distribution of such Securities shall be deemed to have
     occurred and the Conversion Price shall be adjusted as provided in this
     subparagraph (iii) (and such day shall be deemed to be "the date fixed for
     the determination of the stockholders entitled to receive such
     distribution" and "the record date" within the meaning of the two preceding
     sentences).

          (iv) No adjustment in the Conversion Price shall be required unless
     such adjustment would require a cumulative increase or decrease of at least
     1% in such price; provided, however, that any adjustments that by reason of
     this subparagraph (iv) are not required to be made shall be carried forward
     and taken into account in any subsequent adjustment until made; and
     provided, further, that any adjustment shall be required and made in
     accordance with the provisions of this Section 7 (other than this
     subparagraph (iv)) not later than such time as may be required in order to
     preserve the tax-free nature of a distribution to the holders of shares of
     Class A Common Stock. Notwithstanding any other provisions of this Section
     7, the Corporation shall not be required to make any adjustment of the
     Conversion Price for the issuance of any shares of Class A Common Stock
     pursuant to any plan providing for the reinvestment of dividends in
     securities of the Corporation. All calculations under this Section 7 shall
     be made to the nearest cent (with $.005 being rounded upward) or to the
     nearest 1/10 of a share (with .05 of a share being rounded upward), as the
     case may be. Anything in this paragraph (D) to the contrary
     notwithstanding, the Corporation shall be entitled, to the extent permitted
     by law, to make such reductions in the Conversion Price, in addition to
     those required by this paragraph (D), as it in its discretion shall
     determine to be advisable in order that any stock dividends, subdivision of
     shares, reclassification or combination of shares, distribution of rights
     or warrants to purchase stock or securities, or a distribution of other
     assets

                                      -15-

<PAGE>   16


     (other than cash dividends) hereafter made by the Corporation to its
     stockholders shall not be taxable.

          (v)  Anything in this paragraph (D) to the contrary not withstanding,
     no adjustment in the Conversion Price shall be required upon the issuance
     of any shares of Class A Common Stock to holders of Class B Common Stock,
     upon the conversion thereof, if any, in the case of any adjustment in the
     conversion rate for the Class B Common Stock, or in the case of any
     exchange of shares of Class A Common Stock for Class B Common Stock.

     (E)  If the Corporation shall be a party to any transaction (including
without limitation a merger, consolidation, sale of all or substantially all of
the Corporation's assets or recapitalization of the Class A Common Stock and
excluding any transaction as to which subparagraph (D)(i) of this Section 7
applies) (each of the foregoing being referred to herein as a "Transaction"),
in each case as a result of which shares of Class A Common Stock shall be
converted into the right to receive stock, securities or other property
(including cash or any combination thereof), each share of Convertible
Preferred Stock which is not converted into the right to receive stock,
securities or other property in connection with such Transaction shall
thereafter be convertible into the kind and amount of shares of stock,
securities and other property (including cash or any combination thereof)
receivable upon the consummation of such Transaction by a holder of that number
of shares or fraction thereof of Class A Common Stock into which one share of
Convertible Preferred Stock was convertible immediately prior to such
Transaction, assuming such holder of Class A Common Stock (i) is not a Person
with which the Corporation consolidated or into which the Corporation merged or
which merged into the Corporation or to which such sale or transfer was made,
as the case may be ("Constituent Person"), or an affiliate of a Constituent
Person and (ii) failed to exercise his or her rights of election, if any, as to
the kind or amount of stock, securities and other property (including cash)
receivable upon such Transaction (provided that if the kind or amount of stock,
securities and other property (including cash) receivable upon such Transaction
is not the same for each share of Class A Common Stock of the Corporation held
immediately prior to such Transaction by other than a Constituent Person or an
affiliate thereof and in respect of which such rights of election shall not
have been exercised ("non-electing share"), than for the purpose of this
paragraph (E) the kind and amount of stock, securities and other property
(including cash) receivable upon such Transaction by each non-electing share
shall be deemed to be the kind and amount so receivable per



                                      -16-

<PAGE>   17


share by the plurality of the non-electing shares). The Corporation shall not
be a party to any Transaction unless the terms of such Transaction are
consistent with the provisions of this paragraph (E) and it shall not consent
or agree to the occurrence of any Transaction until the Corporation has entered
into an agreement with the successor or purchasing entity, as the case may be,
for the benefit of the holders of the Convertible Preferred Stock that will
contain provisions enabling the holders of the Convertible Preferred Stock that
remains outstanding after such Transaction to convert into the consideration
received by holders of Class A Common Stock at the Conversion Price in effect
immediately prior to such Transaction. The provisions of this paragraph (E)
shall similarly apply to successive Transactions.

          (F)  If:

               (i)  the Corporation shall declare a dividend (or any other
          distribution) on the Class A Common Stock (other than in cash out of
          profits or surplus and other than the Rights); or

              (ii)  the Corporation shall authorize the granting to the holders
          of the Class A Common Stock of rights or warrants (other than the
          Rights) to subscribe for or purchase any shares of any class or any
          other rights or warrants (other than the Rights); or

             (iii)  there shall be any reclassification of the Class A Common
          Stock (other than an event to which subparagraph (D)(i) of this
          Section 7 applies) or any consolidation or merger to which the
          Corporation is a party and for which approval of any stockholders of
          the Corporation is required, or the sale or transfer of all or
          substantially all of the assets of the Corporation as an entirety; or

              (iv)  there shall occur the voluntary or involuntary liquidation,
          dissolution or winding up of the Corporation,

then the Corporation shall cause to be filed with the Transfer Agent and shall
cause to be mailed to the holders of shares of the Convertible Preferred Stock
at their address as shown on the stock records of the Corporation, as promptly
as possible, but at least 15 days prior to the applicable date hereinafter
specified, a notice stating (A) the date on which a record is to be taken for
the purpose of such dividend, distribution or rights or warrants, or, if a
record is not to be taken, the date on which the holders of Class A Common
Stock of record to


                                      -17-

<PAGE>   18
be entitled to such dividend, distribution or rights or warrants are to be
determined or (B) the date on which such reclassification, consolidation,
merger, sale, transfer, liquidation, dissolution or winding up is expected to
become effective, and the date on which it is expected that holders of Class A
Common Stock of record shall be entitled to exchange their shares of Class A
Common Stock for securities or other property, if any, deliverable upon such
reclassification, consolidation, merger, sale, transfer, liquidation,
dissolution or winding up.  Failure to give or receive such notice or any defect
therein shall not affect the legality or validity of the proceedings described
in this Section 7.

         (G) Whenever the Conversion Price is adjusted as herein provided, the
Corporation shall promptly file with the Transfer Agent an officer's certificate
setting forth the Conversion Price after such adjustment and setting forth a
brief statement of the facts requiring such adjustment which certificate shall
be prima facie evidence of the correctness of such adjustment. Promptly after
delivery of such certificate, the Corporation shall prepare a notice of such
adjustment of the Conversion Price setting forth the adjusted Conversion Price
and the effective date of such adjustment and shall mail such notice of such
adjustment of the Conversion Price to the holder of each share of Convertible
Preferred Stock at such holder's last address as shown on the stock records of
the Corporation.

         (H) In any case in which paragraph (D) of this Section 7 provides that
an adjustment shall become effective on the day next following a record date for
an event, the Corporation may defer until the occurrence of such event (A)
issuing to the holder of any share of Convertible Preferred Stock converted
after such record date and before the occurrence of such event the additional
shares of Class A Common Stock issuable upon such conversion by reason of the
adjustment required by such event over and above the Class A Common Stock
issuable upon such conversion before giving effect to such adjustment and (B)
paying to such holder any amount in cash in lieu of any fraction pursuant to
paragraph (C) of this Section 7.

         (I) For purposes of this Section 7, the number of shares of Class A
Common Stock at any time outstanding shall not include any shares of Class A
Common Stock then owned or held by or for the account of the Corporation. The
Corporation shall not pay a dividend or make any distribution on shares of Class
A Common Stock held in the treasury of the Corporation.

         (J) There shall be no adjustment of the Conversion Price in case of the
issuance of any stock of the Corporation


                                      -18-
<PAGE>   19
in a reorganization, acquisition or other similar transaction except as
specifically set forth in this Section 7. If any action or transaction would
require adjustment of the Conversion Price pursuant to more than one paragraph
of this Section 7, only one adjustment shall be made and such adjustment shall
be the amount of adjustment that has the highest absolute value to the holders
of Convertible Preferred Stock as determined by the Board of Directors.

         (K) If the Corporation shall take any action affecting the Class A
Common Stock, other then action described in this Section 7, that in the opinion
of the Board of Directors would materially adversely affect the conversion
rights of the holders of the shares of Convertible Preferred Stock, the
Conversion Price for the Convertible Preferred Stock may be adjusted, to the
extent permitted by law, in such manner, if any, and at such time, as the Board
of Directors may determine to be equitable in the circumstances.

         (L) The Corporation covenants that it will at all times reserve and
keep available, free from preemptive rights, out of the aggregate of its
authorized but unissued shares of Class A Common Stock or its issued shares of
Class A Common Stock held in its treasury, or both, for the purpose of
effecting conversion of the Convertible Preferred Stock, the full number of
shares of Class A Common Stock deliverable upon the conversion of all
outstanding shares of Convertible Preferred Stock not theretofore converted.
For purposes of this paragraph (L), the number of shares of Class A Common
Stock that shall be deliverable upon the conversion of all outstanding shares
of Convertible Preferred Stock shall be computed as if at the time of
computation all such outstanding shares were held by a single holder.

         The Corporation covenants that any shares of Class A Common Stock
issued upon conversion of the Convertible Preferred Stock shall be validly
issued, fully paid and nonassessable. Before taking any action that would cause
an adjustment reducing the Conversion Price below the then-par value of the
shares of Class A Common Stock deliverable upon conversion of the Convertible
Preferred Stock, the Corporation will take any corporate action that, in the
opinion of its counsel, may be necessary in order that the Corporation may
validly and legally issue fully paid and non-assessable shares of Class A Common
Stock at such adjusted Conversion Price.

         The Corporation shall list the shares of Class A Common Stock required
to be delivered upon conversion of the Convertible Preferred Stock, prior to
such delivery, upon each


                                      -19-
<PAGE>   20


national securities exchange, if any, upon which the outstanding Class A Common
Stock is listed at the time of such delivery.

     Prior to the delivery of any securities that the Corporation shall be
obligated to deliver upon conversion of the Convertible Preferred Stock, the
Corporation shall endeavor to comply with all federal and state laws and
regulations thereunder requiring the registration of such securities with, or
any approval of or consent to the delivery thereof by, any governmental
authority.

     (M)  The Corporation will pay any and all documentary, stamp or similar
issue or transfer taxes payable in respect of the issue or delivery of shares
of Class A Common Stock or other securities or property on conversion of the
Convertible Preferred Stock pursuant hereto; provided, however, that the
Corporation shall not be required to pay any tax that may be payable in respect
of any transfer involved in the issue or delivery of shares of Class A Common
Stock or other securities or property in a name other than that of the holder
of the Convertible Preferred Stock to be converted and no such issue or
delivery shall be made unless and until the person requesting any issue or
delivery has paid to the Corporation the amount of any such tax or established,
to the reasonable satisfaction of the Corporation, that such tax has been paid.

     Section 8.  Ranking.  Any class or series of stock of the Corporation
shall be deemed to rank:

     (A)  prior to the Convertible Preferred Stock, as to the payment of
dividends and as to distributions of assets upon liquidation, dissolution or
winding up, if the holders of such class or series shall be entitled to the
receipt of dividends and of amounts distributed upon liquidation, dissolution
or winding up in preference or priority to the holders of Convertible Preferred
Stock;

     (B)  on a parity with the Convertible Preferred Stock, as to the payment
of dividends and as to distribution of assets upon liquidation, dissolution or
winding up, whether or not the dividend rates, dividend payment dates or
redemption or liquidation prices per share thereof be different from those of
the Convertible Preferred Stock if the holders of such class of stock or series
and the Convertible Preferred Stock shall be entitled to the receipt of
dividends and of amounts distributable upon liquidation, dissolution or winding
up in proportion to their respective amounts of accrued and unpaid dividends per
share or liquidation preferences, without preference or priority one over the
other; and



                                      -20-
<PAGE>   21

     (C) junior to the Convertible Preferred Stock, as to the payment of
dividends or as to the distribution of assets upon liquidation, dissolution or
winding up, if such stock or series shall be Class A Common Stock or Class B
Common Stock or if the holders of Convertible Preferred Stock shall be entitled
to receipt of dividends or of amounts distributable upon liquidation,
dissolution or winding up in preference or priority to the holders of shares of
such stock or series.

     Section 9. Voting. Except as otherwise required by applicable law, the
shares of Convertible Preferred Stock shall not have any relative,
participating, optional or other special voting rights and powers and the
consent of the holders thereof shall not be required for the taking of any
corporate action.

     Section 10. Transfer of Convertible Preferred Stock. Shares of Convertible
Preferred Stock may not be directly or indirectly sold, transferred or assigned
by the holders thereof; provided, however, that a holder of shares of
Convertible Preferred Stock may transfer the shares owned thereby to one or
more trusts or other persons the sole beneficiary of which and the holder of
all ownership interests in which is such holder or, in the case of such a
holder that is a trust, to a trust or other persons the sole beneficiaries of
which and holders of all ownership interests in which are those persons who are
the beneficiaries of, grantors of or holders of all ownership interests in such
holder.

     Section 11. Registration Rights. At any time after conversion of any
portion of any holder's shares of Convertible Preferred Stock pursuant to
Section 7 hereof, the Corporation shall, if requested by any such holder, as
expeditiously as possible file a registration statement on a form for general
use under the Securities Act of 1933, as amended, if necessary in order to
permit the sale or other disposition of the shares of Class A Common Stock
issued upon conversion of the Convertible Preferred Stock in accordance with
the intended method of sale or other disposition requested by such holder;
provided, however, that the Corporation shall not be required to register any
shares hereunder unless the aggregate number of shares to be registered under
such registration statement is in excess of 1% of the aggregate number of
shares of Class A Common Stock outstanding on the date of the Corporation's
receipt of such holder's request. Each such holder shall provide all
information reasonably requested by the Corporation for inclusion in any
registration statement to be filed hereunder. The Corporation shall use its best
efforts to cause such registration statement first to become effective and then
to remain effective for such period not in excess of 180 days



                                 -21-
<PAGE>   22


from the day such registration statement first becomes effective as may be
reasonably necessary to effect such sales or other dispositions. The
registration effected under this Section 11 shall be at the Corporation's
expense except for underwriting commissions and the fees and disbursements of
such holder's counsel attributable to the registration of such Class A Common
Stock. In no event shall the Corporation be required to effect more than two
registrations in the aggregate hereunder. The filing of any registration
statement required hereunder may be delayed for such period of time (not to
exceed 60 days) as may reasonably be required to facilitate any public
distribution by the Corporation of Class A Common Stock or Class B Common Stock
or if a special audit of the Corporation would otherwise be required in
connection therewith. If requested by any such holder in connection with such
registration, the Corporation shall become a party to any underwriting
agreement relating to the sale of such shares on terms and including
obligations and indemnities which are customary for parties similarly situated.
Upon receiving any request for registration under this Section 11 from any such
holder, the Corporation agrees to send a copy thereof to any other person known
to the Corporation to be entitled to registration rights under this Section 11,
in each case by promptly mailing the same, postage prepaid, to the address of
record of the persons entitled to receive such copies, and to use its
reasonable efforts to allow any such persons who so request in writing to
participate in such registration.

     Section 12.  Determinations by the Board of Directors.  Any determinations
made in good faith by the Board of Directors of the Corporation under any
provision of this Certificate of Designations, Preferences and Rights shall be
final and binding on all stockholders (including holders of shares of
Convertible Preferred Stock) of the Corporation.



                                      -22-

<PAGE>   23
         Section 13. Record Holders. The Corporation and the Transfer Agent may
deem and treat the record holder of any shares of Convertible Preferred Stock as
the true and lawful owner thereof for all purposes, and neither the Corporation
nor the Transfer Agent shall be affected by any notice to the contrary.

         IN WITNESS WHEREOF, the Corporation has caused this Certificate of
Designations to be made under the seal of the Corporation and signed and
attested by its duly authorized officers this 30th day of December, 1996.

                                             THE JOHN NUVEEN COMPANY


                                             By: /s/ Anthony T. Dean
                                                ---------------------
                                                 Anthony T. Dean
                                                 President and Chief
                                                 Operating Officer








Attest:


By: /s/ James J. Wesolowski
   --------------------------
    James J. Wesolowski
    Secretary







                                      -23-