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                                                                    EXHIBIT 10.1

                              CALL OPTION AGREEMENT

      CALL OPTION AGREEMENT, dated as of December 15, 2004 (this "Agreement"),
among CORPORATE ASSET BACKED CORPORATION, a Delaware corporation (the
"Depositor"), as the sole initial Option Holder (as defined below), UBS
SECURITIES LLC ("UBS Securities"), as the initial purchaser from the Depositor,
and initial and sole holder at the time of execution of this Agreement, of the
Certificates (as defined below), and U.S. BANK TRUST NATIONAL ASSOCIATION, a
national banking association, as the agent appointed by UBS Securities to act on
behalf of UBS Securities and its successors under this Agreement and the Trust
Agreement (as defined below), with respect to the options granted by UBS
Securities to the Depositor under this Agreement. U.S. Bank Trust National
Association, acting for UBS Securities and any subsequent transferee of a
Certificate (as defined below) as agent with respect to such options as set
forth in more detail below, is referred to herein as the "Option Agent."

                                   WITNESSETH:

      WHEREAS, the Depositor has established the CABCO Series 2004-102 Trust
(SBC Communications Inc.) (the "Trust") as a common law trust under the laws of
the State of New York pursuant to the Trust Agreement, dated as of December 15,
2004 (the "Trust Agreement"), between the Depositor and U.S. Bank Trust National
Association, as Trustee and Option Agent;

      WHEREAS, the Trust issued collared floating rate callable certificates
(each, a "Certificate," and collectively, the "Certificates") to the Depositor
evidencing, in the aggregate, the beneficial interests in all the assets of the
Trust;

      WHEREAS, the Depositor is selling all the Certificates issued by the Trust
to UBS Securities, as underwriter pursuant to the Underwriting Agreement, dated
December 7, 2004 (the "Underwriting Agreement"), between the Depositor and UBS
Securities, for resale to investors;

      WHEREAS, as partial consideration for its purchase of each Certificate,
UBS Securities intends to grant to the Depositor an option to purchase that
Certificate upon the terms and subject to the conditions set forth in this
Agreement;

      WHEREAS, each option relating to a single Certificate is referred to
herein as a "Call Option," or the "related Call Option," as the context shall
require;

      WHEREAS, ownership of the Call Options granted hereunder shall be
evidenced by one or more option certificates issued hereunder in definitive
physical form, each of which option certificate shall be substantially in the
form attached as Exhibit C hereto, and each of which option certificates in
definitive physical form shall evidence the number of Call Options set forth on
its face;

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      WHEREAS, the Trust Agreement provides that each subsequent purchaser of a
Certificate agrees, by such purchase, to assume the obligation to perform the
related Call Option, and further agrees to appoint U.S. Bank Trust National
Association as its agent to act on its behalf with respect thereto under this
Agreement and the Trust Agreement; and

      WHEREAS, upon each such transfer of a Certificate (and the automatic
assumption of the obligations under the related Call Option by the transferee),
the transferor of the Certificate shall be released from its obligation to
perform the related Call Option, and the transferor's appointment of U.S. Bank
Trust National Association as its agent with respect thereto shall terminate.

      NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties agree as follows:

                                    ARTICLE I

                                   Definitions

      Section 1.1. Definitions.

      As used in this Agreement, unless the context otherwise requires, the
following terms have the following respective meanings:

            "Affiliate" has the meaning specified in the Trust Agreement.

            "Agreement" has the meaning specified in the preamble to this
      Agreement.

            "Business Day" has the meaning specified in the Trust Agreement.

            "Call Date" means, with respect to any Call Option, the date on
      which settlement of that Call Option occurs pursuant to Section 2.2(d) of
      this Agreement.

            "Call Notice" has the meaning specified in Section 2.2(b) of this
      Agreement.

            "Call Option" has the meaning specified in the recitals to this
      Agreement.

            "Call Option Certificate" has the meaning specified in Section
      2.1(a) of this Agreement.

            "Call Price" means, with respect to each Call Option, an amount
      equal to the sum of (i) the outstanding certificate principal balance on
      the Call Date of the Certificate subject to such Call Option, plus (ii)
      any accrued and unpaid interest on such Certificate through the Call Date.

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            "Certificate Principal Balance" has the meaning specified in the
      Trust Agreement.

            "Certificate Register" has the meaning specified in the Trust
      Agreement.

            "Certificateholder" means each Person in whose name a Certificate is
      registered on the Certificate Register.

            "Certificates" has the meaning specified in the recitals to this
      Agreement.

            "Closing Date" has the meaning specified in the Trust Agreement.

            "Depositor" has the meaning specified in the preamble to this
      Agreement.

            "Depositor Order" has the meaning specified in the Trust Agreement.

            "Option Agent" means U.S. Bank Trust National Association, in its
      capacity as option agent appointed under this Agreement, or any successor
      in such capacity.

            "Option Holder" means, initially, the Depositor, and thereafter with
      respect to all the Call Options, the Person to whom all the Call Options
      have been transferred to as provided herein.

            "Person" means any individual, corporation, estate, limited
      liability company, partnership, joint venture, association, joint stock
      company, trust (including any trust beneficiary), unincorporated
      organization or government or any agency or political subdivision thereof.

            "Protected Purchaser" has the meaning specified in the Uniform
      Commercial Code as is in effect in the State of New York.

            "Rating Agency" has the meaning specified in the Trust Agreement.

            "Responsible Officer" has the meaning specified in the Trust
      Agreement.

            "Securities Act" has the meaning specified in Section 2.4(a) of this
      Agreement.

            "SEC Reporting Failure" has the meaning specified in the Trust
      Agreement.

            "Transfer" means, with respect to any Call Option, the assignment by
      the Option Holder of all rights and delegation by the Option Holder of all
      obligations under such Call Option, and "Transferee" and "Transferor"
      shall have correlative meanings.

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            "Transfer Confirmation" has the meaning specified in Section 2.4(c)
      of this Agreement.

            "Trust" has the meaning specified in the recitals to this Agreement.

            "Trust Agreement" has the meaning specified in the recitals to this
      Agreement.

            "Trust Regulatory Event" has the meaning specified in the Trust
      Agreement.

            "Trust Swap Default" has the meaning specified in the Trust
      Agreement.

            "Trustee" means the trustee from time to time under the Trust
      Agreement.

            "UBS Securities" has the meaning specified in the preamble to this
      Agreement.

            "Underlying Securities" means the $32,500,000 principal amount of
      6.450% Global Notes due June 15, 2034 issued by the Underlying Securities
      Issuer, deposited in the Trust, exclusive of interest accrued from and
      including August 18, 2004, to but excluding the Closing Date (which
      interest has been paid to the Depositor), unless the context otherwise
      requires.

            "Underlying Securities Bankruptcy Default" has the meaning specified
      in the Trust Agreement.

            "Underlying Securities Issuer" means SBC Communications Inc.

            "Underlying Securities Payment Default" has the meaning specified in
      the Trust Agreement.

            "Underwriting Agreement" has the meaning specified in the recitals
      to this Agreement.

      Section 1.2. Interpretive Provisions.

      For all purposes of this Agreement, except as otherwise expressly provided
or unless the context otherwise requires:

            (a) the terms defined in this Article have the meanings assigned to
      them in this Article and include the plural as well as the singular, and
      nouns and pronouns of each gender include each of the other genders;

            (b) all accounting terms not otherwise defined in this Agreement
      have the meanings assigned to them in accordance with generally accepted
      accounting principles in the United States;

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            (c) whenever the words "include," "includes" or "including" are used
      in this Agreement, they shall be deemed to be followed by the words
      "without limitation";

            (d) any reference in this Agreement to any statute, regulation or
      agreement is a reference to such statute, regulation or agreement as
      supplemented or amended from time to time;

            (e) any reference in this Agreement to any Person is a reference to
      such Person and such Person's successors and assigns;

            (f) the Article and Section headings in this Agreement are for
      convenience only and shall not affect the construction of this Agreement;

            (g) when a reference is made in this Agreement to Articles,
      Sections, Exhibits or Schedules, such reference is to Articles or Sections
      of, or Exhibits or Schedules to, this Agreement; and

            (h) all references to a specific time are references to New York
      City time.

                                   ARTICLE II

                                THE CALL OPTIONS

      Section 2.1 Grant of Call Options; Option Holder is Beneficiary.

      (a) UBS Securities, as the initial purchaser of the Certificates from the
Depositor, and initial and sole holder of the Certificates at the time of
execution of this Agreement, hereby grants the Call Options to the Depositor. To
evidence such grant, the Option Agent is hereby directed to concurrently issue
to the Depositor an option certificate in definitive registered physical form (a
"Call Option Certificate") in the Depositor's name in substantially the form
attached as Exhibit C hereto, evidencing 1,300,000 Call Options, and to register
the Depositor's ownership of such 1,300,000 Call Options in the register
referred to in Section 2.4(e).


      (b) The Option Holder shall be an express beneficiary of this Agreement,
entitled to enforce this Agreement directly in its own name against the Option
Agent and the Certificateholders.

      Section 2.2. Manner of and Conditions to Exercise.

      (a) Subject to the terms and conditions of this Agreement, the Call
Options may be exercised by the Option Holder on any Business Day occurring (i)
on or after December 15, 2009, (ii) at any time following the occurrence of an
Underlying Securities Payment Default, an Underlying Securities Bankruptcy
Default, an SEC Reporting

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Failure, a Trust Swap Default or a Trust Regulatory Event, or (iii) at any time
in connection with any tender offer for, a redemption or repurchase of or an
unscheduled payment on the Underlying Securities. The parties acknowledge that,
under the Trust Agreement, if the Trustee receives any announcement, proposal or
notice of any such event set forth in clauses (ii) or (iii) of this section, the
Trustee will be required to deliver a copy of that document to the Option Agent
within two (2) Business Days. The Option Agent agrees to send a copy of each
such document received from the Trustee to each Option Holder on the same day it
is received from the Trustee.

      (b) The Option Holder may exercise the Call Options only upon satisfaction
of each of the following conditions:

            (i) Except in connection with a partial tender offer for, a partial
      redemption or repurchase of or an unscheduled payment on an aggregate
      principal amount of Underlying Securities that is less than the aggregate
      outstanding Certificate Principal Balance of all the Certificates, the
      Option Holder exercises the Call Options with respect to all the
      Certificates outstanding.

            (ii) In connection with a partial tender offer for, a partial
      redemption or repurchase of or an unscheduled payment on an aggregate
      principal amount of Underlying Securities that is less than the aggregate
      outstanding Certificate Principal Balance of all the Certificates, the
      Option Holder exercises the Call Options with respect to the aggregate
      outstanding Certificate Principal Balance of the Certificates equal to the
      aggregate principal amount of Underlying Securities being tendered,
      redeemed, repurchased or repaid.

            (iii) Not fewer than fifteen (15) calendar days nor more than sixty
      (60) calendar days prior to the proposed Call Date, the Option Holder
      shall deliver a notice substantially in the form attached as Exhibit A
      hereto (a "Call Notice") to each of the Option Agent and the Trustee
      specifying the number of Call Options being exercised, the proposed Call
      Date with respect to the Call Options and the account to which the Trustee
      shall deliver the liquidation proceeds from the sale of the Underlying
      Securities deliverable pursuant to Section 2.15 of the Trust Agreement;
      provided, however, that (A) with respect to any exercise of Call Options
      pursuant to Section 2.2(a)(ii), the Call Notice shall be delivered to the
      Option Agent and the Trustee within three (3) Business Days of the
      effectiveness of the Option Holder receiving notice of such events and the
      proposed Call Date shall be the second Business Day after the date of
      delivery of the Call Notice and (B) with respect to any exercise of Call
      Options pursuant to 2.2(a)(iii), the Call Notice shall be delivered to the
      Option Agent and the Trustee no later than seven (7) Business Days prior
      to the expiration of the tender offer acceptance period or the redemption,
      repurchase or payment date, as the case may be.

            (iv) (A) Unless the Option Holder has exercised the Call Options in
      connection with a tender offer, the Option Holder shall have made payment
      of the

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      Call Price under all of the Call Options to the Option Agent, by wire
      transfer in immediately available funds, no later than 10:00 a.m. on the
      proposed Call Date, and (B) if the Option Holder has exercised the Call
      Options in connection with a tender offer, the Trustee shall have received
      payment of the tender price from the Underlying Securities Issuer or other
      purchaser of the Underlying Securities relating to the Certificates
      subject to all of the exercised Call Options (or with respect to the
      portion of the Call Options deemed exercised as provided in Section
      2.2(e), if less than all of the Underlying Securities are tendered by the
      Trustee pursuant to Section 2.15 of the Trust Agreement), in immediately
      available funds, no later than 10:00 a.m. on the later of (i) the Call
      Date specified in the Call Notice or (ii) the earlier to occur of the date
      immediately following the date on which the tender offer is consummated or
      the date on which it expires unconsummated.

      (c) The Option Agent shall notify the Trustee immediately upon its receipt
of a Call Notice. The number of Certificates specified in such Call Notice shall
not be less than the outstanding number of Certificates, except as provided in
Section 2.2(b)(ii). If the number of Certificates specified in such Call Notice
is less than the outstanding number of Certificates (as provided in Section
2.2(b)(ii)), the Trustee shall select the Certificates to be purchased by the
Option Holder. The Certificates so selected shall be a pro rata portion of the
Certificates held by each Certificateholder, provided that purchase of a
fraction of a single Certificate will not be made, and the Trustee shall round
up or down the number of Certificates to be purchased from each
Certificateholder to avoid such fractional purchases.

      (d) On the date specified in the applicable Call Notice, upon satisfaction
of the conditions specified in Section 2.2(b), the Option Agent shall (x) notify
the Trustee of its receipt of the Call Price and the satisfaction of such
conditions, (y) instruct the Trustee to transfer to the Option Holder the number
of Certificates corresponding to the number of Call Options exercised by the
Option Holder, and (z) (i) unless the Call Options were exercised in connection
with a tender offer, remit the amount of the Call Price received from the Option
Holder to the Trustee and instruct the Trustee to pay to each Certificateholder
from whom the Certificates were purchased the Call Price in respect of such
Certificates, or (ii) if the Call Options were exercised in connection with a
tender offer, pay to the Option Holder the amount that the tender offer proceeds
(subject to any early termination payment payable by, or to, the Trust, as the
case may be, under the Swap Agreement (as defined in the Trust Agreement))
exceeds the Call Price, if any.

      (e) Delivery of a Call Notice does not give rise to an obligation on the
part of the Option Holder to pay the Call Price. The Call Notice shall
automatically expire (i) if the Call Options are being exercised other than in
connection with a tender offer, and the Option Holder has not paid the Call
Price to the Option Agent by 10:00 a.m. on the Call Date, or (ii) if the Call
Options are being exercised in connection with any tender offer, if the Trustee
has not received payment of the tender offer proceeds from the Underlying
Securities Issuer or other purchaser by 10:00 a.m. on the later of (A) the date
specified for

                                        7

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settlement in the Call Notice, or (B) the earlier to occur of the date
immediately following the date on which the tender offer is consummated or the
date on which it expires unconsummated. Furthermore, if any Call Options are
exercised in connection with any tender offer and fewer than all of the
Underlying Securities tendered by the Trustee are accepted for payment and paid
for under the tender offer as provided in Section 2.15 of the Trust Agreement,
then the number of Call Options deemed exercised will be reduced so that the
Certificate Principal Balance of the Certificates subject to such exercised Call
Options is equal to the principal amount of Underlying Securities tendered by
the Trustee that are accepted for payment and paid for, and the Call Options
deemed not exercised will remain outstanding. In addition, if the tender offer
is terminated by the person making the tender offer before any Underlying
Securities are accepted for payment and paid for, or if all tenders by the
Trustee of Underlying Securities are rejected, then the applicable Call Notice
will be of no further force and effect, and any related Call Options will be
deemed not exercised and will remain outstanding. If a Call Notice shall expire
for any reason provided for in this Section 2.2(e), none of the Option Holder,
the Option Agent, the Trustee or any Certificateholder shall have any obligation
with respect to the Call Notice, and the expiration of a Call Notice shall in no
way affect the Option Holder's right to deliver a Call Notice at a later date.

      Section 2.3. Legends on Certificates.

      Each Certificate shall bear a legend notifying any Certificateholder of
the existence and terms of the Call Option to which that Certificate is subject,
in substantially the following form:

            BY ACQUIRING OR ACCEPTING ANY INTEREST IN THIS CERTIFICATE, YOU
      ACKNOWLEDGE THAT THIS CERTIFICATE IS SUBJECT TO A PURCHASE OPTION GRANTED
      TO CORPORATE ASSET BACKED CORPORATION, A DELAWARE CORPORATION (THE
      "DEPOSITOR"), BY UBS SECURITIES LLC UNDER THE CALL OPTION AGREEMENT, DATED
      AS OF DECEMBER 15, 2004 (THE "CALL OPTION AGREEMENT"), AMONG THE
      DEPOSITOR, AS THE SOLE INITIAL OPTION HOLDER, UBS SECURITIES LLC, AS THE
      INITIAL PURCHASER FROM THE DEPOSITOR, AND SOLE HOLDER AT THE TIME OF SUCH
      GRANT, OF THE CERTIFICATES, AND U.S. BANK TRUST NATIONAL ASSOCIATION, A
      NATIONAL BANKING ASSOCIATION, ACTING AS OPTION AGENT FOR THE
      CERTIFICATEHOLDERS WITH RESPECT TO THE OPTIONS (THE "OPTION AGENT"), WHICH
      OBLIGATIONS HAVE BEEN ASSUMED BY EACH SUBSEQUENT HOLDER OF SUCH
      CERTIFICATES; YOU AGREE TO ASSUME THE OBLIGATION OF YOUR TRANSFEROR TO
      PERFORM SUCH OPTION; AND YOU ACKNOWLEDGE THAT YOUR TRANSFEROR HAS BEEN
      RELEASED FROM ITS OBLIGATION TO PERFORM SUCH OPTION. THE CALL OPTION
      AGREEMENT PERMITS THE HOLDER OF THE RELATED OPTION TO PURCHASE THIS
      CERTIFICATE FROM YOU, WITHOUT YOUR

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      CONSENT, AT THE TIMES AND ON THE CONDITIONS SPECIFIED IN THE CALL OPTION
      AGREEMENT AT THE CALL PRICE SPECIFIED IN THAT AGREEMENT. THE OPTION MAY BE
      TRANSFERRED FROM TIME TO TIME. UPON THE EXERCISE OF THE RELATED OPTION IN
      THE MANNER SPECIFIED IN THE CALL OPTION AGREEMENT, THE CERTIFICATE WILL BE
      TRANSFERRED TO THE RELEVANT OPTION HOLDER BY THE TRUSTEE, AND YOU WILL BE
      PAID THE CALL PRICE FOR THIS CERTIFICATE IN ACCORDANCE WITH THE TERMS OF
      THE CALL OPTION AGREEMENT, WITHOUT THE REQUIREMENT OF ANY FURTHER ACTION
      BY YOU, EXCEPT THAT, IF THE CERTIFICATES ARE HELD IN DEFINITIVE FORM AT
      SUCH TIME, YOU WILL NOT RECEIVE SUCH CALL PRICE UNLESS AND UNTIL YOU
      SURRENDER THIS CERTIFICATE.

      Section 2.4. Transfer of Call Options.

      (a) Each of the parties to this Agreement acknowledges that the Call
Options are being issued in a transaction exempt from registration under the
U.S. Securities Act of 1933 (the "Securities Act") and that the Call Options
have not been and will not be registered under the Securities Act or any
applicable state securities law of any state and may not be offered, sold,
pledged or otherwise transferred except in a transaction registered pursuant to
the Securities Act or exempt from registration under the Securities Act, and
otherwise in accordance with the terms of this Agreement.

      (b) Promptly following the sale of the Certificates to UBS Securities
pursuant to the Underwriting Agreement and the related grant of the Call Options
by UBS Securities to the Depositor as provided in Section 2.1, and in any event
within forty-five (45) days thereafter, the Depositor shall Transfer 100% of the
Call Options to the London Branch of UBS AG through UBS Securities, as agent
pursuant to the Placement Agency Agreement, dated December 15, 2004, between the
Depositor and UBS Securities. Subject to the terms and conditions set forth in
this Article II, the Option Holder may Transfer all of the Call Options it holds
to another Person at any time; provided that under no circumstances may the Call
Options be re-Transferred to the Depositor.

      (c) The Transfer of the Call Options shall be effected by the delivery of
the relevant Call Option Certificate to the Option Agent for registration in the
name of the Transferee as set forth in Section 2.4(e), in each case with a form
of assignment executed by the Transferor and the execution and delivery by the
Transferor, the Transferee and the Option Agent of a confirmation substantially
in the form attached as Exhibit B hereto (a "Transfer Confirmation").

      (d) The Call Options may be Transferred only in full. No fractional
interest in the Call Options may be transferred, and no interest in the Call
Options may be transferred except in connection with a Transfer of all the
rights and obligations of the Option Holder under and in respect of the Call
Options.

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      (e) The Option Agent shall keep a register in which it shall provide for
the registration of the Call Options and the registration of transfers of the
Call Options. The Option Agent shall record in such register (w) the name and
registered address of the Option Holder, (x) the number of Call Options held by
the Option Holder, (y) the Transfer of the Call Options and (z) the number of
Call Options exercised by the Option Holder and the number of Call Options
cancelled as provided in Section 2.5. The Trustee and the Option Agent may treat
the Person in whose name the Call Options are registered on such register as the
owner of the Call Options for all purposes, and the Trustee and the Option Agent
shall not be affected by any notice to the contrary.

      Section 2.5. Pro Rata Reduction of Call Options Upon Partial Redemption of
Underlying Securities.

      If Underlying Securities are redeemed in part by the Underlying Securities
Issuer and the Option Holder does not exercise the Call Options with respect to
all the Underlying Securities redeemed in such partial redemption, the number of
Call Options held by the Option Holder shall be reduced proportionately so that
the aggregate amount of Certificates callable by the exercise of the Call
Options shall equal the outstanding Certificate Principal Balance of outstanding
Certificates after giving effect to such partial redemption. The Option Agent
shall make such adjustments to its records as shall be necessary to reflect such
reductions and shall notify the Option Holder of such adjustments.

      Section 2.6. Expiration.

      The Call Options shall expire, and the right to exercise the Call Options
shall terminate, on the earlier to occur of (a) the termination of the Trust
Agreement and (b) the liquidation of the Trust.

      Section 2.7. Mutilated, Destroyed, Lost or Stolen Call Option
Certificates.

      (a) If (i) any Call Option Certificate that has been mutilated is
surrendered to the Option Agent, or the Option Agent receives evidence to its
satisfaction of the destruction, loss or theft of any Call Option Certificate,
and (ii) there is delivered to the Option Agent such security or indemnity as
may be required by it to hold it harmless, then, in the absence of notice to the
Option Agent that such Call Option Certificate has been acquired by a Protected
Purchaser, the Option Agent shall execute on behalf of the Certificateholders,
and shall authenticate and deliver, in exchange for or in lieu of any such
mutilated, destroyed, lost or stolen Call Option Certificate, a replacement Call
Option Certificate in respect of a like aggregate Certificate Principal Balance
of Certificates.

      (b) If, after the delivery of a replacement Call Option Certificate in
respect of a mutilated, destroyed, lost or stolen Call Option Certificate
pursuant to Section 2.7(a), a Protected Purchaser of the original Call Option
Certificate in lieu of which such replacement Call Option Certificate was issued
exercises such original Call Option

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Certificate, the Option Agent shall be entitled to recover such replacement Call
Option Certificate from the Person to whom it was delivered or any Person taking
such replacement Call Option Certificate from such Person to whom such
replacement Call Option Certificate was delivered or any assignee of such
Person, except a Protected Purchaser, and shall be entitled to recover upon the
security or indemnity provided therefor to the extent of any loss, damage, cost
or expense incurred by the Option Agent in connection with such exercise.

      (c) In connection with the issuance of any replacement Call Option
Certificate under this Section 2.7, the Option Agent may require the payment by
the holder of the Call Option Certificate of a sum sufficient to cover any tax
or other governmental charge that may be imposed in relation thereto and any
other reasonable expenses (including the fees and expenses of the Option Agent)
connected therewith.

      (d) Any Call Option Certificate issued pursuant to this Section 2.7 in
replacement of any mutilated, destroyed, lost or stolen Call Option Certificate
shall be entitled to all the benefits of this Agreement equally and
proportionately with any and all other Call Option Certificates duly issued
hereunder.

      (e) The provisions of this Section 2.7 are exclusive and shall preclude
(to the extent lawful) all other rights and remedies with respect to the
replacement of mutilated, destroyed, lost or stolen Call Option Certificates.

      Section 2.8. Representations and Warranties of UBS Securities.

      UBS Securities represents and warrants to the Depositor and the Option
Agent as of the date of this Agreement, and as of the time of delivery of the
Call Option Certificates by the Option Agent to the Depositor, that each of the
execution of this Agreement, and the grant of the Call Options and the direction
to the Option Agent to issue the Call Option Certificates in the manner provided
for in Section 2.1, has been duly authorized by UBS Securities and is within the
corporate power and authority of UBS Securities.

      Section 2.9. Representations and Warranties of the Depositor.

      The Depositor represents and warrants to UBS Securities and the Option
Agent as of the date of this Agreement, and as of the time of delivery of the
Call Option Certificates by the Option Agent to the Depositor, that each of the
execution of this Agreement and the receipt by the Depositor of the Call
Options, has been duly authorized by the Depositor and is within the corporate
power and authority of the Depositor.

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                                   ARTICLE III

                                  OPTION AGENT

      Section 3.1. Limitation on Liability.

      The Option Agent shall be protected and shall incur no liability for or in
respect of any action taken, suffered or omitted by it in connection with its
administration of the Call Options in reliance upon any instrument of assignment
or transfer, power of attorney, endorsement, affidavit, letter, notice,
direction, consent, certificate, statement or other paper or document in good
faith believed by it to be genuine and to be signed, executed and, where
necessary, verified and acknowledged, by the proper Person or Persons.

      Section 3.2. Duties of Option Agent.

      The Option Agent undertakes only the specific duties and obligations
imposed under this Agreement upon the following terms and conditions, by all of
which the Depositor, the Option Holder and each Certificateholder shall be
bound:

      (a) The Option Agent may consult with legal counsel (who may be legal
counsel for the Depositor or any of its Affiliates), and the opinion of such
counsel shall be full and complete authorization and protection to the Option
Agent as to any action taken or omitted by it in good faith and in accordance
with such opinion, provided the Option Agent shall have exercised reasonable
care in the selection by it of such counsel.

      (b) Whenever in the performance of its duties under this Agreement, the
Option Agent shall deem it necessary or desirable that any fact or matter be
proved or established by the Depositor or the Trustee prior to taking or
suffering any action under this Agreement, such fact or matter may be deemed to
be conclusively proved and established by a Depositor Order or a certificate
signed by a Responsible Officer of the Trustee and delivered to the Option
Agent; and such Depositor Order or certificate shall be full authorization to
the Option Agent for any action taken or suffered in good faith by it under this
Agreement in reliance upon such Depositor Order or certificate.

      (c) The Option Agent shall be liable under this Agreement only for its own
gross negligence, willful misconduct or bad faith.

      (d) The Option Agent shall not be liable for or by reason of any of the
statements of fact or recitals contained in this Agreement or be required to
verify the same, but all such statements and recitals are and shall be deemed to
have been made by the Depositor only.

      (e) The Option Agent shall not have any responsibility in respect of and
makes no representation as to the validity of the Call Options or the execution
and delivery of this Agreement (except the due execution of this Agreement by
the Option

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Agent); nor shall it be responsible for any breach by the Trustee or the Option
Holder of any covenant or condition contained in this Agreement; nor shall it by
any act under this Agreement be deemed to make any representation or warranty as
to the Certificates or the Underlying Securities.

      (f) The Option Agent is hereby authorized and directed to accept
instructions with respect to the performance of its duties under this Agreement
from the Chairman of the Board, the Chief Executive Officer, the Chief Financial
Officer, the Chief Operating Officer, the President, a Vice President, a Senior
Vice President, a Managing Director, the Treasurer, an Assistant Treasurer, the
Secretary or an Assistant Secretary of the Depositor, and to apply to such
officers for advice or instructions in connection with its duties, and it shall
not be liable for any action taken or suffered to be taken by it in good faith
in accordance with instructions of any such officer.

      (g) The Option Agent and any shareholder, director, officer or employee of
the Option Agent may buy, sell or deal in the Call Options or the Certificates
or otherwise act as fully and freely as though it were not Option Agent under
this Agreement, so long as such persons do so in full compliance with all
applicable laws and, to the extent applicable, the Trust Agreement. Nothing in
this Agreement shall preclude U.S. Bank Trust National Association from acting
in any other capacity for the Trust, the Depositor or for any other legal
entity.

      (h) The Option Agent may execute and exercise any of the rights or powers
hereby vested in it or perform any duty under this Agreement either itself or by
or through its attorneys or agents.

      (i) The Option Agent shall act solely as the agent of the
Certificateholders under this Agreement. The Option Agent shall not be liable
except for the failure to perform such duties as are specifically set forth in
this Agreement, and no implied covenants or obligations shall be read into this
Agreement against the Option Agent, whose duties shall be determined solely by
the express provisions of this Agreement.

      (j) The Option Agent shall not be under any obligation or duty to
institute, appear in or defend any action, suit or legal proceeding in respect
of this Agreement, unless first indemnified to its satisfaction, but this
provision shall not affect the power of the Option Agent to take such action as
the Option Agent may consider proper, whether with or without such indemnity.
The Option Agent shall promptly notify the Depositor and the Trustee in writing
of any claim made or action, suit or proceeding instituted against it arising
out of or in connection with this Agreement.

      Section 3.3. Change of Option Agent.

      (a) The Option Agent may resign and be discharged from its duties under
this Agreement upon thirty (30) days' notice in writing mailed to the Depositor
and the Trustee by registered or certified mail, and to the Option Holder by
first-class mail at the expense of the Depositor; provided that no such
resignation or discharge shall become

                                       13

<PAGE>

effective until a successor Option Agent shall have been appointed under this
Agreement. The Depositor may remove the Option Agent upon three (3) Business
Days' notice in writing, mailed to the Option Agent and to the Option Holder by
first-class mail; provided that no such removal shall become effective until a
successor Option Agent shall have been appointed under this Agreement.

      (b) If the Option Agent shall resign or be removed or shall otherwise
become incapable of acting, the Depositor shall promptly appoint a successor to
the Option Agent. If the Depositor shall fail to make such appointment of a
permanent successor within a period of thirty (30) days after such removal or
within sixty (60) days after notification in writing of such resignation or
incapacity by the resigning or incapacitated Option Agent or by the Option
Holder, then the Option Agent or the Option Holder may apply to any court of
competent jurisdiction for the appointment of such a successor.

      (c) Any entity that may be merged or consolidated with or that shall
otherwise succeed to substantially all of the trust or agency business of the
Option Agent shall be deemed to be the successor Option Agent without any
further action.

      (d) The Option Agent shall at all times be a bank that is not an Affiliate
of the Depositor (but may have normal banking relationships with the Depositor
or the Underlying Securities Issuer and their respective Affiliates), that (i)
is organized and doing business under the laws of any State or the United
States; (ii) is authorized under such laws to exercise corporate trust powers;
(iii) has a combined capital and surplus of at least $50,000,000; (iv) is
subject to supervision or examination by federal or state authority; and (v) has
(or has a parent that has) a long-term unsecured debt rating of at least BBB- by
Standard & Poor's Ratings Services, a Division of The McGraw-Hill Companies,
Inc., or their successor, if any. If the bank publishes reports of condition at
least annually, pursuant to law or to the requirements of the aforesaid
supervising or examining authority, then for the purpose of this Section 3.3(d),
the combined capital and surplus of such corporation shall be deemed to be its
combined capital and surplus as set forth in its most recent report of condition
so published. If at any time the Option Agent shall cease to be eligible in
accordance with the provisions of this Section 3.3(d), the Option Agent shall
resign immediately in the manner and with the effect specified in Section
3.3(a).

                                   ARTICLE IV

                                  MISCELLANEOUS

      Section 4.1. Remedies.

      The remedies of the Option Holder at law in the event of any default or
threatened default by a Certificateholder in the performance of or compliance
with any of the terms of this Agreement are not and will not be adequate and, to
the full extent permitted by law and equity, such terms may be specifically
enforced by a decree for the specific

                                       14

<PAGE>

performance of any agreement contained in this Agreement or by an injunction
against a violation of any of the terms of this Agreement or otherwise.

      Section 4.2. Limitation on Liabilities of the Option Holder.

      Nothing contained in this Agreement or the Call Options shall be construed
as imposing any obligation on the Option Holder to exercise the Call Options or
to purchase any of the Certificates.

      Section 4.3. Notices.

      All notices and other communications under this Agreement shall be in
writing and shall be delivered, or mailed by registered or certified mail,
postage prepaid, return receipt requested, or delivered by a nationally
recognized overnight courier, addressed (a) if to the Option Holder, at the
registered address of the Option Holder as set forth in the register kept by the
Option Agent pursuant to Section 2.4(e), or (b) if to the Option Agent, to U.S.
Bank Trust National Association, 100 Wall Street, Suite 1600, New York, New York
10005, Attention: Corporate Trust, or to such other address of which the Option
Agent shall have given notice to the Option Holder and the Trustee, or (c) if to
the Trust or the Trustee, to the Corporate Trust Office specified in the Trust
Agreement, or (d) if to the Depositor, 445 Broad Hollow Road, Suite 239,
Melville, New York 11747. Any such notice shall be effective on the Business Day
on which it is delivered in person, on the Business Day following the date on
which it is provided to a nationally recognized overnight courier and on the
fifth Business Day following the day on which it is deposited in the mails, in
each case as provided above. Subject to Section 2.2(a), the Option Agent shall
promptly forward to the Option Holder a copy of any notice or other
communication received by it under this Agreement. Notwithstanding the
foregoing, all notices and other communications delivered pursuant to Sections
2.2(a) and 2.2(b) shall be delivered in person or provided to a nationally
recognized overnight courier.

      Section 4.4. Amendment.

      (a) This Agreement may be amended from time to time by the Depositor and
the Option Agent without the consent of the Option Holder, upon receipt of an
opinion of counsel satisfactory to the Option Agent that the execution of the
amendment is authorized or permitted by this Agreement and all conditions
provided for in this Agreement relating to such amendment have been complied
with and that such amendment would not alter the status of the Trust as a
grantor trust under the Internal Revenue Code of 1986, for any of the following
purposes: (i) to cure any ambiguity or to correct or supplement any provision in
this Agreement that may be defective or inconsistent with any other provision in
this Agreement or to provide for any other terms or modify any other provisions
with respect to matters or questions arising under this Agreement that shall not
adversely affect in any material respect the interests of the Option Holder or
any Certificateholder or alter the terms on which the Call Options are
exercisable or the amounts payable upon exercise of the Call Options or (ii) to
evidence

                                       15

<PAGE>

and provide for the acceptance of appointment under this Agreement of a
successor Option Agent.

      (b) This Agreement may also be modified or amended from time to time by
the Depositor and the Option Agent with the consent of the Option Holder, upon
receipt of an opinion of counsel satisfactory to the Option Agent that the
execution of the amendment is authorized or permitted by this Agreement and all
conditions provided for in this Agreement relating to such amendment have been
complied with, for the purpose of adding any provisions to or changing in any
manner or eliminating any of the provisions of this Agreement or the Call
Options or modifying in any manner the rights of the Option Holder; provided,
however, that no such amendment shall (i) adversely affect in any material
respect the interests of the Certificateholders without (x) the consent of all
the Certificateholders and (y) written confirmation from the Rating Agency that
such amendment will not result in a downgrading or withdrawal of its rating of
the Certificates, if then rated by the Rating Agency; (ii) alter the terms on
which the Call Options are exercisable or the amounts payable upon exercise of
the Call Options without the consent of the holders of all the Certificates and
the Call Options; or (iii) reduce or modify the vote required by clause (i) or
(ii) of this proviso without the consent of the holders of 100% of the
Certificates. Notwithstanding any other provision of this Agreement, this
Section 4.4(b) shall not be amended without the consent of the Option Holder.

      (c) Promptly after the execution of any amendment or modification to this
Agreement, the Option Agent shall furnish a copy of such amendment or
modification to the Option Holder, to the Trustee and to the Rating Agency. It
shall not be necessary for the consent of the Option Holder or the Certificates
to approve the particular form of any proposed amendment or modification, but it
shall be sufficient if such consent shall approve the substance of such
amendment or modification. The manner of obtaining and evidencing the
authorization of the execution of such consents shall be subject to such
reasonable regulations as the Option Agent may prescribe.

      Section 4.5. Governing Law.

      THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE
LAWS OF THE STATE OF NEW YORK.

      Section 4.6. Judicial Proceedings.

      Any judicial proceeding brought against any party with respect to this
Agreement may be brought in any court of competent jurisdiction in the County of
New York, State of New York or of the United States of America for the Southern
District of New York and, by execution and delivery of this Agreement or
acceptance of a Certificate, as applicable, each party (a) accepts, generally
and unconditionally, the nonexclusive jurisdiction of such courts and any
related appellate court, and agrees that such party shall be bound by any
judgment rendered thereby in connection with this Agreement, subject to any
rights of appeal, and (b) irrevocably waives any objection that such party may
now

                                       16

<PAGE>

or hereafter have as to the venue of any such suit, action or proceeding brought
in such a court or that such court is an inconvenient forum.

      Section 4.7. Nonpetition Covenant.

      Each of the Option Agent and the Option Holder agrees that it shall not,
until the date which is one year and one day after the payment in full of all
securities issued by the Trust, the Depositor or other trusts formed,
established or settled by the Depositor, acquiesce, petition or otherwise invoke
or cause the Trust, the Depositor, or any such other trust to invoke the process
of the United States of America or any State or other political subdivision of
the United States or any entity exercising executive, legislative, judicial,
regulatory or administrative functions of or pertaining to government for the
purpose of commencing or sustaining a case by or against the Trust, the
Depositor or any such other trust under a federal or state bankruptcy,
insolvency or similar law or appointing a receiver, liquidator, assignee,
trustee, custodian, sequestrator or other similar official of the Trust, the
Depositor or any such other trust or all or any part of the property or assets
of the Trust, the Depositor or any such other trust or ordering the winding up
or liquidation of the affairs of the Trust, the Depositor or any such other
trust.

      Section 4.8. No Recourse.

      Each of the Option Agent and the Option Holder agrees that it shall not
have any recourse to the Trust for any amounts due under this Agreement. This
Section 4.8 shall not affect any rights or remedies that an Option Holder may
have against the Option Agent or the Certificateholders hereunder.

      Section 4.9. New Issuances.

      The Depositor agrees that it shall not cause the Trust to issue additional
Certificates unless it obtains from the holders of such Certificates options on
substantially the same terms as the Call Options and either (x) it resells such
options to the then-current holder of the Call Options, or (y) takes such
measures as shall be necessary to ensure that the issuance of such additional
Certificates does not impair the right of the then holder of the Call Options to
exercise such Call Options on the terms set forth in this Agreement.

                                       17

<PAGE>

      IN WITNESS WHEREOF, the parties hereto have caused this Call Option
Agreement to be executed by their duly authorized officers as of the first date
specified above.

                                           CORPORATE ASSET BACKED CORPORATION,
                                           as sole initial Option Holder

                                           By: /s/ Robert D. Vascellaro
                                               ---------------------------------
                                               Name: Robert D. Vascellaro
                                               Title: Vice President

                                           By: /s/ James Hausmann
                                               ---------------------------------
                                               Name: James Hausmann
                                               Title: Vice President

                                           UBS SECURITIES LLC

                                           By: /s/ Michael Sabatino
                                               ---------------------------------
                                               Name: Michael Sabatino
                                               Title: Director
                                                      Fixed Income Syndicate

                                           By: /s/ James B. Fuqua
                                               ---------------------------------
                                               Name: James B. Fuqua
                                               Title: Director and Counsel
                                                      Region Americas Legal
                                                      Fixed Income Section

                                           U.S. BANK TRUST NATIONAL ASSOCIATION,
                                           as Option Agent and Attorney-in-Fact
                                           for the Certificateholders

                                           By: /s/ David J. Kolibachuk
                                               ---------------------------------
                                               Name: David J. Kolibachuk
                                               Title: Vice President

<PAGE>

                                                                       EXHIBIT A

                              [Form of Call Notice]

                                   CALL NOTICE

      To:   U.S. Bank Trust National Association, as Option Agent
            100 Wall Street, Suite 1600
            New York, New York 10005
            Attention: Corporate Trust

      This Call Notice is delivered pursuant to the Call Option Agreement, dated
as of December 15, 2004 (the "Call Option Agreement"), among Corporate Asset
Backed Corporation, a Delaware corporation (the "Depositor"), as the sole
initial Option Holder, UBS Securities LLC, as the initial purchaser from the
Depositor, and initial and sole holder, at the time of execution of the Call
Option Agreement, of the Certificates, and U.S. Bank Trust National Association,
a national banking association, acting as Option Agent for the holders of
Certificates from time to time (the "Option Agent").

      The undersigned registered holder of the Call Options hereby exercises
________ Call Options for the purchase of Certificates upon and subject to the
terms specified in the Call Option Agreement.

      Subject to the satisfaction of the conditions specified in the Call Option
Agreement, the Call Date in respect of the Call Options so exercised shall be:
___________________ (which date shall be at least fifteen (15) days nor more
than sixty (60) days after the date of delivery of this Call Notice or, if this
Call Notice is delivered with respect to any exercise of Call Options pursuant
to Section 2.2(a)(ii) of the Call Option Agreement, the second Business Day
after the date of delivery of this Call Notice or, if this Call Notice is
delivered with respect to any exercise of Call Options pursuant to Section
2.2(a)(iii) of the Call Option Agreement, no later than seven (7) Business Days
prior to the expiration of the tender offer acceptance period, or the
redemption, repurchase or payment date, as the case may be).

      The undersigned hereby agrees that (i) if the Call Options are being
exercised other than in connection with a tender offer, and the undersigned has
paid the Call Price to the Option Agent by 10:00 a.m. (New York City time) on
the Call Date, or (ii) if the Call Options are being exercised in connection
with any tender offer, if the Trustee has received payment of the Call Price
from the Underlying Securities Issuer or other purchaser by 10:00 a.m. (New York
City time) on the later of (A) the date specified for settlement in the Call
Notice, or (B) the earlier to occur of the date immediately following the date
on which the tender offer is consummated or the date on which it expires
unconsummated, the undersigned will have purchased the Certificates deliverable
pursuant to the Call Options at the time such payment is made. The aggregate
Call Price

<PAGE>

in respect of the Call Options shall be _________________ (insert number
calculated in accordance with the definition of "Call Price" in the Call Option
Agreement).

                                        2

<PAGE>

      The undersigned requests that the liquidation proceeds from the sale of
the Underlying Securities be transferred to the following account in accordance
with the following instructions: _______________________________________________
________________________________________________________________________________
_________________ (insert information required for transfer of liquidation
proceeds).

                                        3

<PAGE>

      All capitalized terms used but not defined in this Call Notice shall have
the meanings assigned to such terms in the Call Option Agreement, and this Call
Notice is subject to the terms and conditions of that Agreement.

      Dated:

                                           [NAME OF OPTION HOLDER]

                                           By:__________________________________
                                              Name:
                                              Title:

                                        4

<PAGE>

                                                                       EXHIBIT B

                         [Form of Transfer Confirmation]

                              TRANSFER CONFIRMATION

      This Transfer Confirmation is delivered pursuant to the Call Option
Agreement, dated as of December 15, 2004 (the "Call Option Agreement"), among
Corporate Asset Backed Corporation, a Delaware corporation (the "Transferor"),
as the sole initial Option Holder, UBS Securities LLC, as the initial purchaser
from the Transferor, and initial and sole holder, at the time of execution of
the Call Option Agreement, of the Certificates, and U.S. Bank Trust National
Association, a national banking association, acting as Option Agent for the
holders of Certificates from time to time (the "Option Agent").

      Capitalized terms used but not defined herein should have the respective
meaning set forth in the Call Option Agreement.

      [Name of Transferor] (the "Transferor") and [Name of Transferee] (the
"Transferee") hereby instruct the Option Agent to register a transfer (the
"Transfer") of 100% of the Call Options owned by the Transferor on the books of
the Option Agent maintained for such purpose.

      As a condition to such Transfer, the Transferee hereby represents and
warrants to the Transferor, the Option Agent and the Trustee referred to in the
Call Option Agreement, for the benefit of the Trust referred to therein, that:

            (1) the Transferee acknowledges that the Call Options have not been
      and will not be registered under the Securities Act of 1933, as amended
      (the "Securities Act"), or any state securities laws, and may not be
      offered or sold in the United States except in accordance with an
      exemption under the Securities Act;

            (2) the Transferee is a "qualified institutional buyer" within the
      meaning of Rule 144A under the Securities Act;

            (3) [with respect to any initial Transfer from the Depositor only:
      Such information regarding the Call Options, the Trust and the
      Certificates as the Transferee has required is, or has been made,
      available to it and it has been afforded the opportunity to ask questions
      and receive answers concerning the terms and conditions of the Call
      Options, and to obtain such additional information as the Transferor
      possesses or can acquire without unreasonable effort or expense that is
      necessary to verify the accuracy of such information;]

            (4) the Transferee agrees that the Call Options may be offered,
      resold, pledged or otherwise transferred only (A) to a person who the
      seller reasonably

<PAGE>

      believes is a "qualified institutional buyer" within the meaning of Rule
      144A under the Securities Act that purchases for its own account or for
      the account of a qualified institutional buyer, pursuant to an exemption
      from registration under the Securities Act, and in compliance with
      applicable state securities laws, and (B) in compliance with the
      securities laws of each other applicable jurisdiction;

            (5) neither the Transferee, nor any person acting on its behalf, has
      offered the Call Options for sale, or solicited any offer to buy the Call
      Options by means of any form of general solicitation or general
      advertising, including but not limited to the methods described in Rule
      502(c) under the Securities Act or in any other manner that would render
      the issuance and sale of the Call Options a violation of the Securities
      Act or require registration pursuant to the Securities Act; and

            (6) the Transferee will notify, and cause each subsequent transferee
      of the Call Options to agree to notify, each subsequent holder of the Call
      Options of the restrictions referred to in paragraph (4) above.

      The address to which any notices addressed to the Transferee should be
addressed is as follows: _______________________________________.

      All capitalized terms used but not defined in this Transfer Confirmation
are used with the meanings specified in the Call Option Agreement, and this
Transfer Confirmation is subject to the terms and conditions of that Agreement.

      This Transfer Confirmation shall be governed by and construed in
accordance with the laws of the State of New York.

      IN WITNESS WHEREOF, the parties have signed their names as of the date set
forth below.

                                           [NAME OF TRANSFEROR],
                                           as Transferor

                                           By: _________________________________
                                               Name:
                                               Title:

                                        2

<PAGE>

                                           [NAME OF TRANSFEREE],
                                           as Transferee

                                           By: _________________________________
                                               Name:
                                               Title:

                                           U.S. BANK TRUST NATIONAL ASSOCIATION,
                                           as Option Agent

                                           By: _________________________________
                                               Name:
                                               Title:

                                        3

<PAGE>

                                                                       EXHIBIT C

                             Call Option Certificate

                                       for

                                  CALL OPTIONS

                       relating to Certificates issued by
              CABCO SERIES 2004-102 TRUST (SBC COMMUNICATIONS INC.)

      THESE CALL OPTIONS HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
1933, AS AMENDED, AND MAY NOT BE TRANSFERRED, SOLD OR OTHERWISE DISPOSED OF
EXCEPT PURSUANT TO AN EXEMPTION UNDER SUCH ACT. THE CALL OPTIONS REPRESENTED
HEREBY MAY BE TRANSFERRED ONLY IN COMPLIANCE WITH THE CONDITIONS SPECIFIED IN
THE CALL OPTION AGREEMENT (AS DEFINED BELOW).

                                  Call Options

                                [_] Call Options

       (Each Call Option relates to $25 principal amount of Certificates)

No. O-[_]                                                                 [Date]

      In connection with CABCO Series 2004-102 Trust (SBC Communications Inc.)
(the "Trust"), a trust created under the laws of the State of New York pursuant
to the Trust Agreement, dated as of December 15, 2004 (the "Trust Agreement"),
between Corporate Asset Backed Corporation, a Delaware corporation (the
"Depositor") and U.S. Bank Trust National Association, a national banking
association, as trustee (the "Trustee") and option agent, for value received,
this Call Option Certificate certifies that [_] or registered assigns, is
entitled to purchase, in whole or part, [_] Certificates issued by the Trust on
any Call Date designated by the holder of these options (these "Call Options")
at a purchase price equal to the Call Price, all subject to the terms and
conditions of the Call Option Agreement, dated as of December 15, 2004 (the
"Call Option Agreement"), among the Depositor, as the sole initial Option
Holder, UBS Securities LLC, as the initial purchaser from the Depositor, and
sole holder at the time of execution of the Call Option Agreement, of the
Certificates, and the Option Agent.

      Certain capitalized terms used in this Call Option Certificate are defined
in the Call Option Agreement and capitalized terms used but not defined herein
or therein shall have the respective meanings set forth in the Trust Agreement.

<PAGE>

      Each of (i) the Option Holder, by its acceptance hereof, and (ii) the
Option Agent agrees, that, without affecting any rights or remedies that the
Option Holder may have against the Option Agent or any Certificateholders under
the Call Option Agreement, it shall not have any recourse to the Trust for any
amount due under these Call Options.

                                           U.S.BANK TRUST NATIONAL
                                               ASSOCIATION,
                                               as Option Agent

                                           By: _________________________________
                                               Authorized Signatory

                                        2

<PAGE>

                               FORM OF ASSIGNMENT

            [To be executed only upon transfer of these Call Options]

      For value received, the undersigned registered holder of these Call
Options hereby sells, assigns and transfers unto _____________ 100% of the Call
Options owned by the undersigned to purchase Certificates, and appoints _____ as
such holder's Attorney to make such transfer on the books of the Option Agent
maintained for such purpose, with full power of substitution in the premises.
The undersigned hereby certifies that it has executed, together with its
transferee and the Option Agent, a Transfer Confirmation in the form attached to
the Call Option Agreement in connection with such transfer.

      Dated:

      (Signature must conform in all respects to name of holder as specified on
the face of these Call Options)

            (Street Address)
      (City State) (Zip Code)

      Signed in the presence of:

                                        3