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                                                                   Exhibit 10.46

                          HOUSTONSTREET EXCHANGE, INC.

                           THIRD AMENDED AND RESTATED
                  RIGHT OF FIRST REFUSAL AND CO-SALE AGREEMENT

         THIS AGREEMENT, as amended and restated, (the "Agreement") is dated as
of March 30, 2001 and is entered into by and among HoustonStreet Exchange, Inc.,
a Delaware corporation, (the "Company"), those holders of shares of the
Company's Common Stock, par value $.01 per share ("Common Stock"), Series A
Convertible Preferred Stock, par value $.01 per share (the "Series A Stock"),
and Series B Convertible Preferred Stock, par value $.01 per share (the "Series
B Stock") listed on SCHEDULE A hereto, and purchasers of units consisting of (x)
Senior Secured Notes (the "Notes"), (y) Warrants to purchase shares of the
Company's Series C Convertible Preferred Stock, par value $.01 per share (the
"Series C Stock") (the "Series C Warrants"), and (z) Warrants to purchase shares
of Common Stock (the "Common Stock Warrants") (the "Unit Purchasers") listed on
SCHEDULE A hereto.

         For the purposes of this Agreement, the term "Unit" or "Units" shall
mean the units consisting of the Notes, the Series C Warrants and the Common
Stock Warrants; provided that any restriction or right which applies to a Unit
shall also apply to the individual components thereof to the extent that they no
longer constitute a Unit.

                                    RECITALS

                  1. BayCorp Holdings, Ltd., a Delaware corporation ("BayCorp"),
Equiva Trading Company, a Delaware general partnership ("Equiva"), Enron Net
Works LLC, a Delaware limited liability company ("Enron"), and those other
persons identified on SCHEDULE A comprise all the holders of shares of Common
Stock, each holding the number of shares of Common Stock listed on SCHEDULE A.

                  2. The Company has issued shares of its Series A Stock
pursuant to a Series A Convertible Preferred Stock Purchase Agreement dated as
of February 2, 2000; has issued shares of its Series B Convertible Preferred
Stock pursuant to a Series B Convertible Preferred Stock Purchase Agreement
dated as of March 31, 2000; and has issued Units pursuant to a Senior Secured
Note and Warrant Purchase Agreement of even date (the "Note and Warrant Purchase
Agreement"). The holders of Series A Stock, Series B Stock and Series C Stock
are sometimes referred to in this Agreement individually as a "Preferred Holder"
and collectively the "Preferred Holders," and collectively, the Preferred
Holders, the Unit Purchasers and the holders of the shares of Common Stock
listed on SCHEDULE A and any of their respective transferees who become a party
to this Agreement pursuant to Section 7.1 hereof are referred to herein as the
"Stockholders."

                  3. Enron purchased 1,781,043 shares of Common Stock pursuant
to that certain Common Stock Purchase Agreement by and between the Company and
Enron dated as of

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September 20, 2000 (the "Enron Stock Purchase Agreement") and Enron may be
entitled to receive an additional 763,305 shares of Common Stock pursuant to the
Enron Stock Purchase Agreement.

                  4. In connection with the Enron Stock Purchase Agreement, on
December 4, 2000, the Company issued to Enron a warrant (which, when
exercisable, will be defined as the "Enron Warrant") to purchase a minimum of
2,544,347 shares of Common Stock (or such number of shares of Common Stock equal
to ten 10% of the outstanding Common Stock on the date of exercise of the Enron
Warrant) pursuant to a Warrant Agreement dated as of September 20, 2000.

                  5. The Company, certain holders of shares of Common Stock and
certain holders of Series A Stock originally entered into this agreement in
furtherance of their desire to protect the management and control of the Company
from influence by any person not acceptable to the Stockholders and to assist
the Preferred Holders in selling their Co-Sale Shares (as defined below). They,
together with the holders of the Series B Stock, amended and restated the
original agreement as of February 2, 2000 to enable the holders of Series B
Stock to become parties to the agreement. They, together with Enron amended and
restated the agreement as of December 4, 2000 (the "Existing Agreement") to
enable Enron to become a party to the Existing Agreement.

                  6. The holders of shares of Common Stock, Series A Stock,
Series B Stock, Enron and the Unit Purchasers now desire to amend and restate
the Existing Agreement in the manner set forth below and to add the Unit
Purchasers as parties to this Agreement.

                  7. (a) As used in this Agreement, (i) the term "Shares" shall
include (A) all shares of capital stock of the Company held by the Stockholders,
whether now owned or hereafter acquired, (B) the Enron Warrant, (C) the Common
Stock Warrants and (D) the Series C Warrants and (ii) the term "Preferred Stock"
shall include all shares of Series A Stock, Series B Stock and Series C Stock.

                  (b) For purposes of calculating any Stockholder's "pro rata"
ownership of Shares, (i) all of the Common Stock Warrants, Series C Stock
Warrants and the Enron Warrant (when it becomes exercisable) shall be deemed to
have been exercised, (ii) all shares of Preferred Stock of the Company shall be
deemed to have been converted into Common Stock and (iii) a Stockholder's "pro
rata ownership interest" shall equal a fraction, (A) the numerator of which
equals the number of Shares then owned by that Stockholder and (B) the
denominator of which equals the aggregate number of Shares then owned by all
Stockholders.

                  (c) For purposes of calculating any Stockholder's "pro rata"
ownership of the Notes, a Stockholder's "pro rata ownership interest" shall
equal a fraction, (i) the numerator of which equals the aggregate principal
amount and accrued and unpaid interest outstanding under the Notes then owned by
that Stockholders and (ii) the denominator of which equals the aggregate
principal amount and accrued and unpaid interest outstanding under all the Notes
then owned by all Stockholders.

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                  8. (a) As used in this Agreement, the term "Co-Sale Shares"
means the shares of (i) the Preferred Stock of the Company and, without
duplication, the shares of the Common Stock issued or issuable upon conversion
of the Preferred Stock of the Company (assuming exercise of the Series C Stock
Warrants), (ii) the shares of Common Stock listed on SCHEDULE A as owned by
Enron, the shares of Common Stock listed on SCHEDULE A to which Enron may be
entitled to pursuant to the Enron Stock Purchase Agreement and, without
duplication, the shares of Common Stock issued or issuable upon exercise of the
Enron Warrant, (iii) the shares of Common Stock issued or issuable upon exercise
of the Common Stock Warrants, (iv) the Common Stock Warrants, (v) the Series C
Warrants, and (vi) the Enron Warrant. Without limiting the preceding sentence,
the shares of the Common Stock listed on SCHEDULE A as owned by Equiva, BayCorp,
Thomas H. Lee Investors Limited Partnership, TSG Equity Fund, L.P., TSG Equity
Partners LLC, Thomas R. Shepherd, T. Nathanael Shepherd and Frank W. Getman are
not Co-Sale Shares.

                  (b) As used in this Agreement, the term "Co-Sale Notes" means
all the Notes.

                  NOW, THEREFORE, for valuable consideration, it is agreed as
follows.

1.       Restrictions on Transfer.

         1.1. Any sale, transfer or other disposition, including without
         limitation, any pledge or hypothecation, whether voluntarily or by
         operation of law ("Transfer") of any of the Shares or Notes by any of
         the Stockholders, other than according to the terms of this Agreement,
         shall be void and transfer no right, title or interest in or to any of
         such Shares or Notes, as the case may be, to the purported transferee.

         1.2. An original copy of this Agreement, duly executed by each of the
         parties hereto, shall be delivered to the Secretary of the Company and
         maintained at the principal executive office of the Company and made
         available for inspection by any person requesting it.

         1.3. Each of the Stockholders agrees to present the certificates
         representing the Shares presently owned or hereafter acquired by it to
         the Secretary of the Company and allow the Secretary to stamp on the
         certificate in a prominent manner the following legend:

                  "The sale or other disposition of any of the shares
                  represented by this certificate is restricted by a Right of
                  First Refusal and Co-Sale Agreement, dated as of March 30,
                  2001, as amended from time to time, among certain of the
                  stockholders of this Company and this Company (the
                  "Agreement"). A copy of the Agreement is available for
                  inspection during normal business hours at the principal
                  executive office of this Company."

2.       Transfers Not Subject to Restrictions.

         2.1. A bona fide pledge of Shares or Notes by a Stockholder wherein the
         pledgee

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         agrees in writing to be bound by the provisions of this Agreement as
         and to the same extent as the Stockholders shall not be deemed to
         violate the provisions of Section 1.1.

         2.2. The rights of the Company and the Stockholders under Sections 4
         and 5 hereof shall not apply to any Transfer of Shares or Notes by a
         Stockholder to any person that directly, or indirectly through one or
         more intermediaries, controls, or is controlled by, or is under common
         control with, that Stockholder (the "Affiliate"), provided the
         Affiliate provides the Company and the Stockholders with a written
         agreement to be bound hereby to the same extent as the Stockholders.

         2.3. The rights of the Company and the Stockholders under Section 4 and
         5 hereof shall not apply to any Transfer of Shares or Notes by BayCorp
         that involves the spinoff of its Shares or Notes offered to
         substantially all stockholders of BayCorp or any similar transaction
         that results in stockholders of BayCorp acquiring Shares or Notes or
         the right to acquire Shares or Notes from BayCorp, such Shares or Notes
         or right to acquire Shares or Notes in an amount that is pro rata to
         each such stockholder's holdings of BayCorp capital stock.

         2.4. The rights of the Company and the Stockholders under Section 4 and
         5 hereof shall not apply to (a) the first 1,000,000 shares of Common
         Stock that BayCorp transfers (in addition to any exempted Transfers
         pursuant to Section 2.3) and (b) the first 481,500 shares of Common
         Stock that Equiva transfers, in each case such number of shares to be
         adjusted for stock splits, stock dividends, recapitalizations and other
         similar events.

         2.5 The rights of the Company and the Stockholders under the last
         sentence of Section 3.2, Section 3.3, Section 4, Section 5 and Section
         6 hereof shall not apply to any Transfer by Enron to (a) any person or
         entity that directly, or indirectly through one or more intermediaries,
         controls or is controlled by or is under common control with Enron (an
         "Enron Affiliate") or (b) any person or entity in which an Enron
         Affiliate serves as the general partner, managing member, or in a
         similar capacity; provided that any transferee pursuant to clauses (a)
         or (b) shall provide the Company with a written undertaking to be bound
         hereby to the same extent as the Stockholders. For purposes of this
         Section 2.5, the term "control" means the possession, directly or
         indirectly, of the power to direct or cause the direction of the
         management and policies of a person or entity, whether through
         ownership, by contract or otherwise.

3.       Offer of Sale; Notice of Proposed Sale.

         3.1. If a Stockholder desires to transfer any of its Shares or Notes,
         or any interest in its Shares or Notes, in any transaction other than a
         Transfer specified in Section 2 of this Agreement, that Stockholder
         (the "Initial Selling Stockholder") shall first deliver written notice
         of its desire to do so (the "Notice") to the Company and each of the
         Stockholders, in the manner prescribed in Section 10.4 of this
         Agreement.

         3.2. The Notice must specify: (i) the name and address of the party to
         which the Initial Selling Stockholder proposes to transfer the Shares
         or Notes, as the case may be,

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         or an interest in the Shares or Notes, as the case may be (the
         "Offeror"), (ii) the number of Shares or Notes, as the case may be, the
         Initial Selling Stockholder proposes to transfer (the "Offered Shares
         or Notes"), (iii) the consideration per Share or Note, as the case may
         be, to be delivered to the Initial Selling Stockholder for the proposed
         Transfer, (iv) all other material terms and conditions of the proposed
         transaction and (v) that the Offeror has agreed to purchase all of the
         Offered Shares or Notes, as the case may be, on the terms and
         conditions set forth in the Notice. The giving of the Notice shall
         constitute an irrevocable offer by the Initial Selling Stockholder to
         sell the Offered Shares or Notes, as the case may be, to the Company
         and/or the Stockholders on the terms and conditions contained in the
         Offer.

         3.3. If a majority of the members of the Company's Board of Directors
         (excluding members employed or designated by the Initial Selling
         Stockholder) determine in good faith that the proposed transferee is a
         direct competitor of the Company, then (i) the Company shall so inform
         the Initial Selling Stockholder within 10 days after the Notice is
         deemed to have been delivered to the Company and (ii) the Initial
         Selling Stockholder shall not transfer any of its Shares or Notes, as
         the case may be, to the proposed transferee.

4.       Company's Option to Purchase.

         4.1. Subject to Sections 4.5 and 6.1, the Company shall have the first
         option to purchase all or any part of the Offered Shares or Notes, as
         the case may be, for the consideration per share and on the same terms
         and conditions specified in the Notice. The Company may only exercise
         such option, if at all, by written notice to the Initial Selling
         Stockholder and the other Stockholders no later than 15 days after the
         Notice is deemed to have been delivered to the Company.

         4.2. In the event the Company does not exercise its option within such
         15-day period with respect to all of the Offered Shares or Notes, as
         the case may be, the Company shall, by the last day of such period,
         give written notice of that fact to the Initial Selling Stockholder and
         the other Stockholders (the "Stockholder Notice"). The Stockholder
         Notice shall specify the number of Offered Shares or Notes, as the case
         may be, not to be purchased by the Company (the "Remaining Shares or
         Notes").

         4.3. In the event the Company duly exercises its option to purchase all
         or any part of the Offered Shares or Notes, as the case may be, the
         closing of such purchase shall take place at the offices of the Company
         on the later of (i) the date five days after the expiration of such
         15-day period, (ii) the date that the Stockholders consummate their
         purchase of Remaining Shares or Notes under Section 5.3 hereof or (iii)
         the date the Initial Selling Stockholder consummates its sale of the
         Shares or Notes, as the case may be, to the Offeror.

         4.4. To the extent that the consideration proposed to be paid by the
         Offeror for the Offered Shares or Notes, as the case may be, consists
         of property other than cash or a promissory note, the consideration
         required to be paid by the Company and/or the

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         Stockholders exercising their options under Sections 4 and 5 hereof may
         consist of cash equal to the value of such property, as determined in
         good faith by agreement of the Initial Selling Stockholder and the
         Company and/or the Stockholders acquiring such Offered Shares or Notes,
         as the case may be. In the event the parties are unable to agree upon
         the cash value of the property offered in consideration for the Offered
         Shares or Notes, as the case may be, the value of such property shall
         be determined by a firm of qualified independent appraisers of
         recognized national standing selected by the Board of Directors of the
         Company, whose determination shall be final and binding on all parties.

         4.5. Notwithstanding anything to the contrary herein, neither the
         Company nor any of the Stockholders shall have any right to purchase
         any of the Offered Shares or Notes, as the case may be, hereunder
         unless the Company and/or the Stockholders exercise their option or
         options to purchase all of the Offered Shares or Notes, as the case may
         be.

5.       Stockholders' Option to Purchase.

         5.1. Subject to Sections 4.5 and 6.1, each Stockholder shall have an
         option, exercisable for a period of 15 days from the date of delivery
         of the Stockholder Notice, to purchase, on a pro rata basis according
         such Stockholder's "pro rata ownership interest" of Shares or Notes, as
         the case may be, the Remaining Shares or Notes, as the case may be, for
         the consideration per share and on the same terms and conditions set
         forth in the Notice. Such options shall be exercised, if at all, by
         delivery by such Stockholder of written notice to the Secretary of the
         Company and the Initial Selling Stockholder. Alternatively, each
         Stockholder that is a holder of Co-Sale Shares or Notes, as the case
         may be, shall have the option, within the same 15-day period, to notify
         the Secretary of the Company and the Initial Selling Stockholder of its
         desire to participate in the sale of the Offered Shares or Notes, as
         the case may be, on the same terms set forth in the Notice, and the
         number of Co-Sale Shares or Notes, as the case may be, it wishes to
         sell; provided that no Stockholder may exercise both of the foregoing
         options.

         5.2. In the event options to purchase have been exercised by the
         Stockholders with respect to some but not all of the Remaining Shares
         or Notes, as the case may be, those Stockholders who have validly
         exercised their options within the 15-day period specified in Section
         5.1 shall have an additional option, for a period of five days next
         succeeding the expiration of such 15-day period, to purchase all or any
         part of the balance of such Remaining Shares or Notes, as the case may
         be, on the same terms and conditions set forth in the Notice, which
         option shall be exercised by the delivery of written notice to the
         Secretary of the Company and the Initial Selling Stockholder. In the
         event there are two or more such Stockholders that choose to exercise
         the last-mentioned option for a total number of Remaining Shares or
         Notes, as the case may be, in excess of the number available, the
         Remaining Shares or Notes, as the case may be, available for each such
         Stockholder's option shall be allocated to such Stockholder pro rata
         based on the "pro rata ownership interest" of Shares or Notes, as the
         case may be, of the Stockholders so electing.

         5.3. If the options to purchase the Remaining Shares or Notes, as the
         case may be, are

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         exercised in full by the Stockholders, the Company shall immediately
         notify all of the exercising Stockholders and the Initial Selling
         Stockholder of that fact. The closing of the purchase of the Remaining
         Shares or Notes, as the case may be, shall take place at the offices of
         the Company or at such other place agreed upon by the parties no later
         than seven days after the date of such notice to the Stockholders.

6.       Failure to Fully Exercise Options; Co-Sale.

         6.1. If the Company and the Stockholders do not exercise their options
         to purchase all of the Offered Shares or Notes, as the case may be,
         within the periods described in this Agreement (the "Option Period"),
         then all options of the Company and the Stockholders to purchase the
         Offered Shares or Notes, as the case may be, whether exercised or not,
         shall terminate, but each holder of Co-Sale Shares or Notes, as the
         case may be, which has given notice pursuant to Section 5 of such
         holder's desire to sell Co-Sale Shares or Notes, as the case may be, in
         the transaction (a "Participating Co-Sale Seller"), shall be entitled
         to do so pursuant to this Section. The Company shall promptly, on
         expiration of the Option Period, notify the Offeror and the Initial
         Selling Stockholder of the aggregate number of Co-Sale Shares or Notes,
         as the case may be, the Participating Co-Sale Sellers wish to sell. The
         Initial Selling Stockholder shall use its commercially reasonable
         efforts to interest the Offeror in purchasing, in addition to the
         Offered Shares or Notes, as the case may be, the Co-Sale Shares or
         Notes, as the case may be, that the Participating Co-Sale Sellers wish
         to sell. If the Offeror does not wish to purchase all of the Co-Sale
         Shares or Notes, as the case may be, made available by the Initial
         Selling Stockholder and the Participating Co-Sale Sellers, then each
         Participating Co-Sale Seller and the Initial Selling Stockholder shall
         be entitled to sell, at the price (subject to adjustment as described
         below) and on the same terms and conditions set forth in the Notice (or
         in the case of a Participating Co-Sale Seller offering Co-Sale Shares
         that are shares of Preferred Stock of the Company when the Initial
         Selling Stockholder offers shares of Common Stock, then such terms and
         conditions as would result if such offered Co-Sale Shares were deemed
         to have been converted into Common Stock), its "pro rata portion" of
         the Shares or Notes, as the case may be, being sold to the Offeror. In
         determining the "pro rata portion" of the Shares being sold to the
         Offeror of a Participating Co-Sale Seller or an Initial Selling
         Stockholder for purposes of this Section 6, (i) all shares of Preferred
         Stock shall be deemed to have been converted into Common Stock, and
         (ii) a Participating Co-Sale Seller's or an Initial Selling
         Stockholders' "pro rata portion" shall be represented by a fraction,
         (A) the numerator of which equals the number of Shares (on an
         as-converted basis) then owned by the Participating Co-Sale Seller or
         the Initial Selling Stockholder and (B) the denominator of which equals
         the aggregate number of Shares (on an as-converted basis) then owned by
         the Initial Selling Stockholder and all of the Participating Co-Sale
         Sellers; provided, that, to the extent that (a) the Offered Shares
         consist of capital stock of the Company and the Co-Sale Shares consist
         of the Enron Warrant, the Common Stock Warrants or the Series C
         Warrants (collectively, the "Warrants"), the price for such Warrants
         shall be discounted by then current exercise price of such

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         Warrants, (b) to the extent that the Offered Shares consist of Warrants
         and the Co-Sale Shares consist of Common Stock or Preferred Stock, the
         price for such Common Stock or Preferred Stock, as the case may be,
         shall be increased by an amount equal to the then current exercise
         price of such Warrants and (c) to the extent that the Offered Shares
         consist of Warrants and the Co-Sale Shares consist of Warrants with
         different exercise prices, the price for the Warrants constituting
         Co-Sale Shares shall be equitably adjusted to reflect such difference;
         provided, further, that, in the event that any adjustment pursuant to
         clauses (a) or (c) above shall result in a price that is equal to or
         less than zero (0) for the Warrants constituting Co-Sale Shares, the
         Participating Co-Sale Seller shall not be entitled to include such
         Co-Sale Shares. In determining the "pro rata portion" of the Notes
         being sold to the Offeror of a Participating Co-Sale Seller or an
         Initial Selling Stockholder for purposes of this Section 6, a
         Participating Co-Sale Seller's or an Initial Selling Stockholders' "pro
         rata portion" shall be represented by a fraction, (A) the numerator of
         which equals aggregate principal amount and accrued and unpaid interest
         outstanding under the Notes then owned by the Participating Co-Sale
         Seller or the Initial Selling Stockholder and (B) the denominator of
         which equals the aggregate principal amount and accrued and unpaid
         interest outstanding under the Notes then owned by the Initial Selling
         Stockholder and all of the Participating Co-Sale Sellers.

         The transaction contemplated by the Notice shall be consummated not
         later than 60 days after the expiration of the Option Period.

         6.2. If the Participating Co-Sale Sellers do not elect to sell the full
         number of Co-Sale Shares or Notes, as the case may be, which they are
         entitled to sell pursuant to Section 6.1, the Initial Selling
         Stockholder shall be entitled to sell to the Offeror, according to the
         terms set forth in the Notice, that number of its own Co-Sale Shares
         (or Shares, if the Initial Selling Stockholder is not a holder of
         Co-Sale Shares) or Notes, as the case may be, which equals the
         difference between the number of Shares or Notes, as the case may be,
         desired to be purchased by the Offeror and the number of Co-Sale Shares
         or Notes, as the case may be, the Participating Co-Sale Sellers are
         entitled to sell pursuant to Section 6.1. If the Initial Selling
         Stockholder wishes to transfer any such Shares or Notes, as the case
         may be, at a price per share which differs from that set forth in the
         Notice, upon terms different from those previously offered to the
         Company and the Stockholders, to a transferee other than the Offeror,
         or more than 60 days after the expiration of the Option Period, then,
         as a condition precedent to such transaction, such Shares or Notes, as
         the case may be, shall again be subject to the restrictions set forth
         in this Agreement.

         6.3. Without implying that unauthorized Transfers are permissible
         hereunder, the proceeds of any Transfers made by the Initial Selling
         Stockholder without compliance with the provisions of this Section 6
         shall be deemed to be held in constructive trust in such amount as
         would have been due the Participating Co-Sale Sellers if the Initial
         Selling Stockholder had complied with this Agreement.

7.       Additional Transfer Restrictions.

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         7.1. Notwithstanding any provision in this Agreement to the contrary,
         no Transfer of any Shares or Notes other than pursuant to Section 2.3
         or Section 2.4 may be made (i) unless the transferor provides, if
         required by the Company, evidence and assurances satisfactory to the
         Company in its reasonable discretion (which may include an opinion of
         counsel and/or appropriate representations and warranties from the
         transferor and transferee), that such Transfer is made in compliance
         with all applicable securities laws and regulations promulgated
         thereunder and (ii) unless the transferee executes and delivers a
         written instrument acknowledging the receipt of a copy of the
         provisions and restrictions contained in this Agreement and agreeing to
         comply herewith and be bound hereby.

         7.2. Any transferee of Shares or Notes, by reason of such transfer,
         shall become a party to and be bound by this Agreement, as the same may
         be amended from time to time, and if and when a transferee becomes the
         owner of any Shares or Notes, this Agreement shall be amended by the
         Stockholders in any reasonable manner required to continue to provide
         the rights and protections contemplated herein in substantially the
         same manner in which such rights and protections were provided prior to
         such transferee becoming an owner of Shares or Notes. Any transferee of
         Shares or Notes shall have all of the rights and obligations under this
         Agreement of the Stockholder that transferred Shares or Notes, as the
         case may be, to that transferee.

8.       Termination of Agreement.

         8.1. This Agreement shall terminate upon the earliest of the following
         events:

                  (a) The sale of all or substantially all of the assets or
                  business of the Company, by merger, sale of assets or
                  otherwise (except a merger or consolidation in which the
                  holders of capital stock of the Company immediately prior to
                  such merger or consolidation continue to hold immediately
                  following such merger or consolidation at least a majority of
                  the voting power of the capital stock of the surviving
                  corporation);

                  (b) The closing of the Company's initial firm commitment
                  underwritten public offering of shares of Common Stock
                  pursuant to an effective registration statement under the
                  Securities Act of 1933, as amended, resulting in at least
                  $25,000,000 of gross proceeds to the Company at a price to the
                  public of at least $9.50 per share (subject to appropriate
                  adjustment for stock splits, stock dividends,
                  recapitalizations and other similar events); or

                  (c) such time as less than 25% of the aggregate of all
                  originally issued shares of Preferred Stock are outstanding
                  (such number to be proportionately adjusted in the event of
                  any stock splits, stock dividends, recapitalizations or
                  similar events occurring on or after the date hereof).

         8.2. The provisions of Sections 3, 4, 5, 6 and 7 hereof shall not apply
         to any sale of Shares or Notes pursuant to a transaction referred to in
         Sections 8.1(a) or 8.1(b) above.

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9. Transfers of Rights. Subject to Section 8 hereof, this Agreement, and the
rights and obligations of each Stockholder hereunder, may be assigned by such
Stockholder to any person or entity to which Shares or Notes are transferred
(other than a transferee that acquires shares pursuant to Section 2.3, 2.4 or
2.5 hereof) by such Stockholder, and such transferee shall be deemed a
"Stockholder" for purposes of this Agreement.

10. General.

         10.1. Severability. The invalidity or unenforceability of any provision
         of this Agreement shall not affect the validity or enforceability of
         any other provision of this Agreement.

         10.2. Specific Performance. In addition to any and all other remedies
         that may be available at law in the event of any breach of this
         Agreement, each Stockholder shall be entitled to specific performance
         of the agreements and obligations of the Company and each other
         Stockholder hereunder and to such other injunctive or other equitable
         relief as may be granted by a court of competent jurisdiction.

         10.3. Governing Law. This Agreement shall be governed by and construed
         in accordance with the internal laws of the State of Delaware (without
         reference to the conflicts of law provisions thereof).

         10.4. Notices. All notices, requests, consents and other communications
         under this Agreement shall be in writing and shall be deemed delivered
         (i) three business days after being sent by certified mail, return
         receipt requested, postage prepaid or (ii) one business day after being
         sent via a reputable nationwide overnight courier service guaranteeing
         next business day delivery, in each case to the intended recipient at
         his or its address as set forth SCHEDULE A hereto.

         Any party may give any notice, request, consent or other communication
         under this Agreement using any other means (including, without
         limitation, personal delivery, messenger service, telecopy, first class
         mail or electronic mail), but no such notice, request, consent or other
         communication shall be deemed to have been duly given unless and until
         it is actually received by the party for whom it is intended. Any party
         may change the address to which notices, requests, consents or other
         communications hereunder are to be delivered by giving the other
         parties notice in the manner set forth in this Section.

         10.5. Complete Agreement. This Agreement, the Note and Warrant Purchase
         Agreement, the Fourth Amended and Restated Stockholders' Voting
         Agreement and the Amended and Restated Investor Rights Agreement
         constitute the entire agreement and understanding of the parties hereto
         with respect to the subject matter hereof, and supersede all prior
         agreements and understandings relating to such subject matter.

         10.6. Amendments. No amendment, modification or termination of, or
         waiver (other

                                       10
<PAGE>
         than a waiver as to only the rights of the particular party granting
         the waiver) under any provision of this Agreement relating to the
         Shares shall be valid unless in writing and signed by Preferred Holders
         holding 85% of the voting power of the Co-Sale Shares (assuming the
         exercise of the Series C Warrants, the exercise of the Common Stock
         Warrants and the conversion into Common Stock of all securities
         convertible thereinto) and stockholders holding 85% of the Notes (based
         upon aggregate principal and accrued and unpaid interest) then held by
         all of the Stockholders; provided that:

                  (a) the consent of the Company or BayCorp, as applicable,
                  shall be required to effect any amendment, modification or
                  termination of, or waiver under, any provision of this
                  Agreement that adversely affects such party's rights or
                  obligations set forth in this Agreement (it being agreed that
                  adding subsequent purchasers does not adversely affect such
                  party's rights or obligations set forth in this Agreement);

                  (b) any amendment, modification or waiver (other than a waiver
                  as to only the rights of the particular party granting the
                  waiver) under this Agreement that is not executed by all of
                  the parties hereto shall affect all of the parties hereto in
                  the same fashion;

                  (c) subsequent purchasers of the Company's capital stock, or
                  options to purchase such capital stock, securities convertible
                  into such capital stock or Notes, shall constitute
                  "Stockholders" for purposes of this Agreement and the
                  securities of the Company owned by such purchasers shall
                  constitute "Shares" and "Co-Sale Shares" for purposes of this
                  Agreement without any amendment hereto;

                  (d) subsequent purchasers of Units shall constitute "Unit
                  Purchasers" for purposes of this Agreement and the Units owned
                  by such purchasers shall constitute "Units" for purposes of
                  this Agreement without any amendment hereto; and

                  (e) any amendment, modification or termination effected in
                  accordance with this Section 10.6 shall be binding upon all
                  parties hereto.

         10.7. Pronouns. Whenever the context may require, any pronouns used in
         this Agreement shall include the corresponding masculine, feminine or
         neuter forms, and the singular form of nouns and pronouns shall include
         the plural, and vice versa.

         10.8. Counterparts; Facsimile Signatures. This Agreement may be
         executed in any number of counterparts, each of which shall be deemed
         to be an original, and all of which together shall constitute one and
         the same document. This Agreement may be executed by facsimile
         signatures.

         10.9. Section Headings. The section headings are for the convenience of
         the parties and in no way alter, modify, amend, limit or restrict the
         contractual obligations of the parties.

                                       11
<PAGE>
IN WITNESS WHEREOF, this Third Amended and Restated Right of First Refusal and
Co-Sale Agreement has been executed by the parties hereto as of the day and year
first above written.

                                       HOUSTONSTREET EXCHANGE, INC.

                                       By: /s/ Frank W. Getman Jr.
                                           -------------------------------------
                                           Frank W. Getman Jr.
                                           President and Chief Executive Officer

                                       BAYCORP HOLDINGS, LTD.

                                       By: /s/ Frank W. Getman Jr.
                                           -------------------------------------
                                           Frank W. Getman Jr.
                                           President and Chief Executive Officer

                                       EQUIVA TRADING COMPANY

                                       By: /s/ W.J. Finnerty
                                           -------------------------------------
                                           Name: W.J. Finnerty
                                           Title: Sr. VP-ETCO

                                       THOMAS H. LEE INVESTORS
                                       LIMITED PARTNERSHIP

                                       By: /s/ Wendy Masler
                                           -------------------------------------
                                           Name: Wendy Masler
                                           Title: SVP + Treasurer

                                       TSG  EQUITY FUND, L.P.

                                       By: /s/ T. Nathanael Shepherd
                                           -------------------------------------
                                           Name: T. Nathanael Shepherd
                                           Title: President

                                       TSG EQUITY PARTNERS LLC

                                       By: /s/ T. Nathanael Shepherd
                                           -------------------------------------
                                           Name: T. Nathanael Shepherd
                                           Title:President


                                       THOMAS R. SHEPHERD

                                       /s/ Thomas R. Shepherd
                                       -----------------------------------------

                                       12
<PAGE>
                                       T. NATHANAEL SHEPHERD

                                       /s/ T. Nathanael Shepherd
                                       -----------------------------------------


                                       FRANK W. GETMAN JR.

                                       /s/ FRANK W. GETMAN JR.
                                       -----------------------------------------


                                       ENRON NET WORKS LLC

                                       By:
                                           -------------------------------------
                                           Name:
                                           Title:


                                       MICHAEL DESROCHERS

                                       /s/ Michael Desrochers
                                       -----------------------------------------


                                       BARRETT MCDEVITT

                                       /s/ Barrett McDevitt
                                       -----------------------------------------


                                       PETER GETMAN

                                       /s/ Peter Getman
                                       -----------------------------------------


                                       JAMES S. GORDON

                                       /s/ James S. Gordon
                                       -----------------------------------------


                                       MITCHELL JACOBS

                                       /s/ Mitchell Jacobs
                                       -----------------------------------------

                                      A-13
<PAGE>
                                       WILLIAMS ENERGY MARKETING &
                                       TRADING COMPANY

                                       By: /s/ William C. Lawson
                                           -------------------------------------
                                           Name: William C. Lawson
                                           Title: Director


                                       SAPIENT CORPORATION

                                       By:
                                           -------------------------------------
                                           Name:
                                           Title:

                                       BOWSTREET.COM, INC.

                                       By:
                                           -------------------------------------
                                           Name:
                                           Title:

                                       OMEGA ADVISORS, INC. for and on behalf of
                                       Omega Capital Partners, L.P.,
                                       Omega International Partners, L.P.,
                                       Omega Overseas Partners, Ltd., and
                                       various institutional  accounts under the
                                       investment  management of Omega Advisors,
                                       Inc.

                                       By: /s/ David Bloom
                                           -------------------------------------
                                           Name: David Bloom
                                           Title: Chief Operating Officer

                                       ELLIOTT ASSOCIATES, L.P.

                                       By: /s/ Paul Singer
                                           -------------------------------------
                                           Name:
                                           Title:

                                       KROAD VENTURES, L.P.
                                       By:      KRoad Partners, LLC
                                                    Its General Partner

                                       By: /s/ David L. Tohir
                                           -------------------------------------
                                           Name: David L. Tohir
                                           Title: Senior Vice President


                                      A-14
<PAGE>
                                       VIVENDI, S.A.

                                       By:
                                           -------------------------------------
                                           Name:
                                           Title:

                                       CONOCO, INC.

                                       By: /s/ E.L. Oshlo
                                           -------------------------------------
                                           Name: E.L. Oshlo
                                           Title: Vice President

                                       MICROARTS CORPORATION AFFILIATES

                                       By:
                                           -------------------------------------
                                           Name:
                                           Title:



                                      A-15
<PAGE>
                                                                      SCHEDULE A


<TABLE>
<CAPTION>
HOLDERS OF COMMON STOCK                                       SHARES
<S>                                                    <C>
BayCorp Holdings, Ltd.                                    10,000,000
       Attn. Frank W. Getman Jr.
       222 International Drive, Suite 125
       Portsmouth, New Hampshire 03801-6809

Equiva Trading Company                                     4,814,815
       Attention:  William J. Finnerty
       One Allen Center
       500 Dallas Street
       Houston, Texas 77002

Thomas H. Lee Investors Limited Partnership                  200,000
       Attention: Soren Oberg
       75 State Street
       Boston, Massachusetts 02109

TSG Equity Fund, L.P.                                         55,217
       Attention: Thomas R. Shepherd
       636 Great Road
       Stow, MA 01775

TSG Equity Partners LLC                                          667
       Attention: Thomas R. Shepherd
       636 Great Road
       Stow, MA 01775

Thomas R. Shepherd                                             7,939
       c/o TSG Equity Partners LLC
       636 Great Road
       Stow, MA 01775

T. Nathanael Shepherd                                          2,844
       c/o TSG Equity Partners LLC
       636 Great Road
       Stow, MA 01775

Frank W. Getman Jr.                                           60,000
       222 International Drive, Suite 125
       Portsmouth, New Hampshire 03801-6809
</TABLE>

                                      A-1
<PAGE>
<TABLE>
<S>                                                    <C>
Enron Net Works LLC                                        1,781,043
       Attention: Compliance Department; Donna Lowry
       1400 Smith Street
       Houston, Texas 77002
                                                         -----------
                                    TOTAL                 16,922,525
</TABLE>

<TABLE>
<CAPTION>
HOLDERS OF CONTINGENT RIGHTS TO RECEIVE COMMON STOCK          SHARES
<S>                                                    <C>

Enron Net Works LLC                                          763,305
       Attention: Compliance Department; Donna Lowry
       1400 Smith Street
       Houston, Texas 77002
</TABLE>

<TABLE>
<CAPTION>
HOLDERS OF WARRANTS TO PURCHASE COMMON STOCK                  SHARES
<S>                                                    <C>
Enron Net Works LLC                                        2,544,347
       Attention: Compliance Department; Donna Lowry
       1400 Smith Street
       Houston, Texas 77002



HOLDERS OF SERIES A CONVERTIBLE PREFERRED STOCK               SHARES

Michael Desrochers                                            22,222
Barrett McDevitt                                              22,223
Peter Getman                                                  22,222
       c/o MicroArts Corporation
       655 Portsmouth Avenue
       Greenland, Portsmouth 03840

James S. Gordon                                               26,667
       86 Mt. Vernon Street
       Boston, Massachusetts 02108
</TABLE>

                                      A-2
<PAGE>
<TABLE>
<S>                                                    <C>
Williams Energy Marketing & Trading Company                  800,000
       Attention: Bill Hobbs
       One Williams Center
       P.O. Box 2848
       Tulsa, Oklahoma 74172

Sapient Corporation                                          266,667
       Attention: Wendy Kelly
       One Memorial Drive
       Cambridge, Massachusetts 02142

Bowstreet.com, Inc.                                           66,667
       Attention: Jack Serfass
       1 Harbour Place
       Portsmouth, New Hampshire 03801

Equiva Trading Company                                     1,066,667
       Attention:  William J. Finnerty
       One Allen Center
       500 Dallas Street
       Houston, Texas 77002

Omega Advisors, Inc.                                         666,667
       Attention:  Lawrence M. Robbins
       Wall Street Plaza
       88 Pine Street, 31st Floor
       New York, New York 10005

Elliott Associates, L.P.                                     666,667
       Attention: Michael R. Latina
       712 Fifth Avenue, 36th Floor
       New York, New York 10019

Equiva Trading Company                                       133,334
       Attention:  Arthur Nicoletti
       One Allen Center - 500 Dallas
       Houston, Texas 77002
                                                          ----------
                                    TOTAL                  3,760,003
</TABLE>


                                      A-3
<PAGE>
<TABLE>
<CAPTION>
HOLDERS OF SERIES B CONVERTIBLE PREFERRED STOCK               SHARES
<S>                                                    <C>
 KRoad Ventures, L.P.
        330 Madison Ave.                                     416,667
        25th Floor
        New York, NY 10017

 Vivendi, S.A.                                               166,667
        c/o KRoad Ventures, L.P.
        330 Madison Ave.
        25th Floor
        New York, NY 10017

 Conoco, Inc                                                 500,000
        600 N. Dairy Ashford
        MA 3128
        Houston, TX 77079-1175
                                                          ----------
                                     TOTAL                 1,083,334
</TABLE>

PURCHASERS OF UNITS

<TABLE>
<CAPTION>
             Name and Address               Units/Principal     No. of Series C   No. of Common Stock
             ----------------               ---------------     ---------------   -------------------
                                            Amount of Notes      Stock Warrants        Warrants
                                            ---------------      --------------        --------
<S>                                         <C>                 <C>               <C>
BayCorp Holdings, Ltd.                       $8,419,842.00         56,132,280          2,806,614
     Attn:  Frank W. Getman, Jr
     222 International Drive, Suite 125
     Portsmouth, NH 03801-6809
TSG Equity Fund, L.P.                        $   17,763.11            118,421              5,920
     Attn:  Thomas R. Shepherd
     636 Great Road
     Stow, MA 01775
TSG Equity Partners LLC                      $      179.43              1,196                 60
     Attn:  Thomas R. Shepherd
     636 Great Road
     Stow, MA 01775
Thomas R. Shepherd                           $    1,503.60             10,024                501
     c/o TSG Equity Partners LLC
     636 Great Road
     Stow, MA 01775
T. Nathanael Shepherd                        $      553.86              3,692                185
     c/o TSG Equity Partners LLC
     636 Great Road
     Stow, MA 01775
James S. Gordon                              $  187,500.00          1,250,000             62,500
     86 Mt. Vernon Street
     Boston, MA 02108
</TABLE>

                                      A-4
<PAGE>
<TABLE>
<S>                                         <C>                 <C>               <C>
Mitchell Jacobs                              $  125,000.00            833,334             41,667
     1 Energy Road
     North Dartmouth, MA 02747
KRoad Ventures                               $  160,000.00          1,066,667             53,334
     330 Madison Avenue
     25th Floor
     New York, NY 10017
Equiva Trading Company                       $1,394,354.00          9,295,693            464,785
     Attention:  William J. Finnerty
     One Allen Center
     500 Dallas Street
     Houston, TX 77002
Omega Advisors, Inc.                         $  180,000.00          1,200,000             60,000
     Attention: Ed Levy
     Wall Street Plaza
     88 Pine Street, 31st Floor
     New York, NY 10005
Michael A. Desrochers                        $   83,333.00            555,553             27,778
     c/o MicroArts Corporation
     655 Portsmouth Avenue
     Portsmouth, NH 03840
Barrett McDevitt                             $   83,334.00            555,560             27,778
     c/o MicroArts Corporation
     655 Portsmouth Avenue
     Portsmouth, NH 03840
Peter L. Getman                              $   83,333.00            555,553             27,778
     c/o MicroArts Corporation
     655 Portsmouth Avenue
     Portsmouth, NH 03840
Conoco, Inc.                                 $  437,819.00          2,918,793            145,940
     600 N. Dairy Ashford
     MA 3128
     Houston, TX 77079-1175
Thomas H. Lee Investors Limited              $   75,000.00            500,000             25,000
Partnership
     75 State Street
     Boston, MA 02109
</TABLE>


                                      A-5