Document:

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                                                                EXHIBIT 4.27

                                MASTER AGREEMENT

THIS AGREEMENT is dated April 22, 2001

AMONG:

                  GREGORY B. MAFFEI, of
                  1500 42nd Avenue E., No. 4
                  Seattle, WA 98112

                  ("GBM")

AND:

                  WORLDWIDE FIBER HOLDINGS LTD., an Alberta corporation with an
                  office at 1000 - 1066 West Hastings Street, Vancouver, British
                  Columbia

                  ("WFH")

AND:

                  360NETWORKS INC., a Nova Scotia corporation with an office at
                  1500 - 1066 West Hastings Street, Vancouver, British Columbia

                  ("360")

WHEREAS:

(A)      360 currently employs GBM as its Chief Executive Officer. In connection
         with GBM's employment, GBM purchased from 360 62,000,000 shares of 360
         (the "PURCHASED SHARES") pursuant to the Stock Purchase Agreement. To
         finance GBM's purchase of the Purchased Shares, he delivered the
         Original Note.

(B)      Pursuant to Section 8 of the Stock Purchase Agreement, GBM was granted
         the Prior GBM Put, whereby GBM has the right to require 360 to purchase
         certain Purchased Shares at their fair market value, as determined
         pursuant to the Stock Purchase Agreement. Prior to any of the
         transactions contemplated hereby, GBM had informed 360 that he may be
         compelled to exercise the Prior GBM Put to reduce the risk to him of
         his recourse obligations under the Original Note.

(C)      360 does not currently have a right to set-off its obligations under
         the Prior GBM Put against the Original Note. Further, the Prior GBM Put
         is not currently delegable to WFH under present circumstances. If GBM
         were to exercise the Prior GBM Put, it could therefore adversely affect
         360's liquidity and capital resources, cause compliance issues under
         360's existing credit facilities, and be perceived adversely by the
         public investment

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                                     - 2 -

         community. Accordingly, neither WFH nor 360 believe it would be in its
         best interests for GBM to exercise the Prior GBM Put.

(D)      360 and WFH wish to avoid the risks described in recital C and, to do
         so, they have requested GBM's cooperation and agreement to facilitate a
         transaction whereby WFH would assume 360's obligation for GBM's put
         rights contained in the Stock Purchase Agreement and clarify and amend
         WFH's put obligations to GBM in the form of the GBM Put provided herein
         and GBM would agree to cancel his put rights against 360, and 360 would
         cause the GBM Note to be sold to WFH in exchange for a recourse
         promissory note made by WFH in favour of 360finance ltd. in an amount
         equal to the principal and interest owing under the GBM Note. GBM has
         agreed to release 360 from its obligations with respect to the Prior
         GBM Put only in the event that WFH, 360 and GBM enter into this
         Agreement, whereby, among other things, WFH delivers the GBM Put.

(E)      WFH would not be willing to purchase the GBM Note unless GBM agrees to
         increase the interest rate charged on the GBM Note by 0.1% and would
         not be willing to deliver the GBM Put unless GBM agrees to forbear his
         rights to exercise the GBM Put for a period of up to 9 months (on the
         terms and conditions set forth in the Forbearance Agreement) and GBM
         agrees to grant to WFH certain set-off rights. GBM is willing to enter
         into the Forbearance Agreement and increase the interest rate on his
         note, and thereby facilitate the sale of the GBM Note to WFH and 360's
         delegation of its put obligations to WFH, on the condition that the GBM
         Note be amended to, among other things, make it non-recourse (except to
         the Shares) and to grant GBM certain set-off rights, and the further
         condition that the parties execute this Agreement.

(F)      After giving effect to the transactions contemplated by this Agreement
         and the documents referenced herein, GBM will be indebted to WFH in the
         amount of $77,500,000, plus accrued but unpaid interest, as evidenced
         by the Revised GBM Note issued in substitution for the GBM Note.

(G)      In consideration of revisions which are incorporated in the Revised GBM
         Note and the provision by WFH of the GBM Put, GBM has agreed to pledge
         the Shares, and deliver possession of certificates evidencing the
         Shares, to WFH to be dealt with as provided herein.

(H)      360 shall retain the Repurchase Right to repurchase some of GBM's
         Shares, which may be exercised pursuant to the Stock Purchase
         Agreement.

(I)      The transactions described in Recitals C through G are occurring
         concurrently with the execution of this Agreement and each such
         transaction is dependent upon a concurrent occurrence of the others.

NOW THEREFORE THIS AGREEMENT WITNESSES that, in consideration of the mutual
agreements and covenants described above, contained herein, contained in
documents contemplated herein, and for other good and valuable consideration,
the receipt and sufficiency of which is hereby acknowledged, the parties hereto
mutually agree as follows:

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DEFINITIONS AND EXHIBITS

1.            In this Agreement the following terms have the meaning ascribed
              thereto:

         AGGREGATE PUT AMOUNT LIMIT means that number of Shares which, when
         multiplied by the Fair Market Value applicable to such Shares on an
         Exercise Date, would at such time satisfy the outstanding principal and
         interest on the Revised GBM Note;

         ALTERNATIVE FAIR MARKET VALUE (LISTED SECURITIES) means, for the
         purposes of this Agreement:

         (a) at any time the Subordinate Voting Shares are Listed Securities,
         the Alternative Fair Market Value (Listed Securities) of a Subordinate
         Voting Share shall equal the simple average of the closing sale prices
         of the Subordinate Voting Shares on the Applicable Canadian Exchange
         (defined in (b) below) for each of the trading days on which there is a
         closing price falling not more than 20 trading days immediately prior
         to the Exercise Date, provided that:

                  (i) if there is no published market for Subordinate Voting
         Shares in Canada, the calculation above will be made solely by
         reference to the published market outside Canada on which the greatest
         volume of trading in the Subordinate Voting Shares occurred during the
         said 20 trading days;

                  (ii) if there has been trading of the Subordinate Voting
         Shares on the relevant published market for fewer than 10 of the said
         20 trading days, the Alternative Fair Market Value (Listed Securities)
         of a Subordinate Voting Share is the average of the following prices
         for each day of the said 20 trading days:

                           (A)      the average of the bid and ask prices for
         each day on which there was no trading ; and

                           (B)      the closing price of Subordinate Voting
         Shares for each day that there was trading;

         (b) "Applicable Canadian Exchange" means, if there is only one
         published market for Subordinate Voting Shares in Canada such published
         market (which at the date hereof is the TSE), and if there is more than
         one published market in Canada for Subordinate Voting Shares, the
         exchange on which the greatest volume of trading of Subordinate Voting
         Shares occurred during the said 20 trading days;

         (c) for purposes of this definition, the Alternative Fair Market Value
         (Listed Securites) of a Multiple Voting Share will be equal to the
         Alternative Fair Market Value (Listed Securities) of a Subordinate
         Voting Share;

         (d) for purposes of this definition, all references to closing prices
         and bid and ask prices shall be as published in the Eastern Edition of
         The Wall Street Journal, or if not published therein, as published in
         The Globe & Mail, and shall be expressed in US dollars.

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                                     - 4 -

         AMENDED STOCK PURCHASE AGREEMENT means the Amended and Restated Stock
         Purchase Agreement dated April 22, 2001 between GBM and 360;

         CERTIFICATE means a certificate signed by GBM and an officer of 360
         (other than GBM) confirming the number of Vested Shares and Unvested
         Shares as of the date thereof.

         CLOSING has the meaning ascribed thereto in s.6;

         CLOSING DATE has the meaning ascribed thereto in s.6;

         EXERCISE DATE means the date on which GBM notifies WFH of GBM's
         exercise of the GBM Put;

         FAIR MARKET VALUE means, for purposes of this Agreement:

         (a) at any time when the Subordinate Voting Shares are not traded on
         any one or more of the Nasdaq National Market Quotation System
         ("NASDAQ"), the New York Stock Exchange ("NYSE"), the American Stock
         Exchange ("AMEX") or the Toronto Stock Exchange ("TSE" and together
         with NASDAQ, NYSE AND AMEX, the "EXCHANGES") (a listed security traded
         on any of NASDAQ, NYSE, AMEX or TSE being a "LISTED SECURITY"), the
         fair market value of a Subordinate Voting Share of 360 as determined,
         at WFH's sole expense, by an appraisal firm or investment bank of
         national standing experienced in the valuation of such securities
         ("VALUATION FIRM") selected in good faith by GBM and approved by WFH,
         which approval shall not be unreasonably withheld or delayed. The
         determination of Fair Market Value of a share of a Subordinate Voting
         Share shall be based on the value in U.S. dollars that a willing buyer
         with knowledge of all relevant facts would pay a willing seller for all
         the outstanding equity securities of 360 in connection with an auction
         of 360 as a going concern assuming bidders are prepared to pay a
         control premium and without any discount for lesser voting rights, lack
         of liquidity, lack of control, minority holder status or similar
         factors. The Fair Market Value shall be determined by the Valuation
         Firm as soon as practicable but in any event not later than 60 days
         following the date of the appointment of the Valuation Firm. If WFH has
         not approved a Valuation Firm within 15 days of the proposal of such
         Valuation Firm by GBM hereunder, then (without prejudice to GBM's other
         rights and remedies) GBM may request the President of the American
         Arbitration Association to appoint a Valuation Firm, which will then be
         the Valuation Firm for the transaction in question. 360 shall furnish
         to the Valuation Firm all reasonably available information requested by
         the Valuation Firm. The Fair Market Value established by the Valuation
         Firm (or by the written agreement of all parties to the transaction)
         shall be final and binding with respect to each required Valuation;

         (b) at any time the Subordinate Voting Shares are Listed Securities,
         the Fair Market Value of a share of Subordinate Voting Shares shall
         equal the average of the closing sale prices of the Subordinate Voting
         Shares (and in the event that the Subordinate Voting Shares are traded
         on more than one Exchange, the average of the closing sale prices on
         each such Exchange on which they are traded) (or, if no sales take
         place on any such trading day on any Exchange on which the Subordinate
         Voting Shares are traded, the

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         closing sale price for the Subordinate Voting Shares on such Exchange
         shall be the average of the closing bid and ask prices of the
         Subordinate Voting Shares on such trading day on such Exchange)
         expressed in U.S. dollars and as published in the Eastern Edition of
         The Wall Street Journal (except with respect to the TSE, which shall be
         as published in The Globe & Mail) for the 20 consecutive trading days
         immediately prior to the Exercise Date;

         (c) for purposes of this definition, the Fair Market Value of a
         Multiple Voting Share will be equal to the Fair Market Value of a
         Subordinate Voting Share;

         FORBEARANCE AGREEMENT means the Forbearance Agreement made April 22,
         2001 between GBM and WFH, a copy of which is attached as Exhibit 3;

         GBM NOTE means the Original Note which has been assigned by 360finance
         ltd. and reissued by GBM in favour of WFH, a copy of which is attached
         hereto as Exhibit 2;

         GBM PUT means the put right described herein;

         MARKET VALUE, with respect to any Share, means Fair Market Value;
         provided, however, that if the Subordinate Voting Shares are Listed
         Securities and Fair Market Value is 115% or greater than Alternative
         Fair Market Value (Listed Securities), then Market Value means
         Alternative Fair Market Value (Listed Securities);

         MULTIPLE VOTING SHARES means multiple voting shares of 360;

         NOTICE means a written notice from any party addressed to all other
         parties hereto;

         ORIGINAL NOTE means the promissory note dated December 22, 1999
         delivered pursuant to the Stock Purchase Agreement;

         PERMITTED TRANSFEREE shall mean:

                  (a)      GBM's spouse or children or grandchildren (in each
                  case, natural or adopted);

                  (b)      any trust established solely for GBM's benefit or
                  the benefit of GBM's spouse or children or grandchildren (in
                  each case, natural or adopted);

                  (c)      any corporation or partnership in which the direct
                  and beneficial owner of all of the equity interest is GBM or
                  GBM's spouse or children or grandchildren (in each case,
                  natural or adopted) (or any trust for the benefit of such
                  persons); or

                  (d)      the heirs, executors, administrators or personal
                  representatives upon the death of GBM or upon the incompetency
                  or disability of GBM for purposes of the protection and
                  management of the assets of GBM;

         where such Permitted Transferee agrees in a writing satisfactory to WFH
         that (A) the provisions of this Agreement including without limitation
         acknowledgement that the

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         Shares are subject to the security interest constituted by the Pledge
         and the provisions of this Agreement including the set-off rights
         contained herein, will continue to apply to the transferred Shares in
         the hands of such Permitted Transferee and (B) such Permitted
         Transferee will not transfer, or permit any transfer, of the equity in
         such Permitted Transferee to any entity other than one that also
         constitutes a Permitted Transferee;

         PLEDGE has the meaning ascribed thereto in s.3 hereof;

         PRIOR GBM PUT means the put right described in the Stock Purchase
         Agreement;

         REPURCHASE PRICE means the price per Share payable by 360 upon exercise
         of the Repurchase Right;

         REPURCHASE RIGHT means the right described in the Amended Stock
         Purchase Agreement whereby 360 has the right in certain circumstances
         to purchase Unvested Shares;

         REVISED GBM NOTE means the GBM Note as amended and restated in order to
         make clear the agreed amendments, a copy of which is attached as
         Exhibit 1;

         SALE means a sale, or a hedge or other monetization, of any Vested
         Shares by GBM;

         SHARES means the Vested Shares and the Unvested Shares (as adjusted
         from time to time after the date hereof for stock splits, stock
         dividends, reverse stock splits, combinations, recapitalizations and
         similar transactions affecting the Shares);

         SPECIFIED SHARE PRICE means, with respect to one Subordinate Voting
         Share, the sum of US$1.25 (as adjusted for stock splits, stock
         dividends, reverse stock splits, combinations, recapitalizations and
         similar transactions affecting the Subordinate Voting Shares) and
         interest thereon in an amount equal to 6.20% per annum, compounded
         annually on December 21, 2000, from December 22, 1999 to April 21,
         2001, and thereafter in an amount equal to 6.30% per annum, compounded
         annually, on December 21 in each year thereafter;

         STOCK PURCHASE AGREEMENT means the stock purchase agreement dated as of
         December 22, 1999 between GBM and 360 (then known as Worldwide Fibre
         Inc.);

         SUBORDINATE VOTING SHARES means subordinate voting shares of 360;

         UNVESTED SHARES means Shares owned by GBM which remain subject to the
         Repurchase Right, being at the date hereof 30,690,008 Subordinate
         Voting Shares; and

         VESTED SHARES means Shares owned by GBM which are not subject to the
         Repurchase Right, being at the date hereof 21,469,992 Subordinate
         Voting Shares and 9,840,000 Multiple Voting Shares.

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DELIVERY OF REVISED GBM NOTE AND THE FORBEARANCE AGREEMENT

2. GBM agrees to deliver concurrently herewith the Revised GBM Note evidencing
the agreed amendments referred to in the Recitals and the parties shall mark the
GBM Note "Cancelled". Such replacement of the GBM Note by the Revised GBM Note
shall not be considered in any way a repayment of the GBM Note. GBM and WFH will
further execute and deliver the Forbearance Agreement concurrently herewith.

PLEDGE BY GBM IN FAVOUR OF WFH

3. GBM hereby mortgages, pledges, charges, assigns and grants a continuing
security interest in and to the Shares together with any substitutions therefor
and the proceeds (subject to, and as limited by, the terms of s.5 hereof)
thereof and all dividends (including stock dividends and dividends consisting of
securities), interest, income or other distributions in respect of such shares
to and in favour of WFH, as general and continuing collateral security for the
payment of the Revised GBM Note (the "PLEDGE"). GBM herewith delivers to WFH the
certificate(s) representing the Shares (other than a certificate or certificates
for 5,660,000 Vested Subordinate Voting Shares) for the purposes of perfecting
the security interest and pledge hereof, together with duly executed stock
transfer powers in respect thereof. GBM will deliver a certificate or
certificates for the said 5,660,000 Shares if required by s.5 hereof.

Upon payment in full of the Revised GBM Note, the Vested Shares and Unvested
Shares shall be released from the Pledge and

         (a) certificate(s) for the Vested Shares shall be delivered to GBM; and

         (b) certificates for the Unvested Shares shall be delivered to and held
         by 360 until the expiry of the Repurchase Option.

The parties shall mutually agree upon the respective number of Vested Shares and
Unvested Shares that are subject to the Pledge at the time of the said release.

Upon appointment of any collateral agent pursuant to s.4 , WFH will deliver any
Shares then held pursuant to the Pledge to the collateral agent.

APPOINTMENT OF COLLATERAL AGENT

4. WFH, GBM and 360 agree that they will use reasonable commercial efforts in
good faith to appoint an institutional trustee as a collateral agent to hold the
Shares subject to the Pledge and to deal with them on reasonably satisfactory
terms. The identity of the collateral agent and the terms of the agreement under
which the collateral agent holds the Shares shall be subject to the approval of
WFH, GBM and 360, acting reasonably and in good faith. In the event that the
parties are unable to reach agreement on the identity of the institutional
trustee or the terms of the agreement within 21 days of the date of this
Agreement, the matters shall be referred to and finally resolved by arbitration
under the Rules of the British Columbia International Commercial Arbitration
Centre (the "CENTRE"). The appointing authorities shall be the Centre. The case
shall be administered by the Centre in accordance with its "Procedures for Cases
Under the BCICAC Rules". The place of arbitration shall be Vancouver, British
Columbia, Canada.

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PARTIAL RELEASE ON SALE BY GBM

5. Notwithstanding the Pledge, GBM shall have the right to enter into a Sale,
provided that GBM shall pay to WFH, within 30 days of the closing of any Sale,
as a partial payment on a pro-rata basis of the principal amount (and accrued
and unpaid interest on such principal amount) of the Revised GBM Note, an amount
equal to the Specified Share Price for each Share subject to the Sale. For
greater certainty, it is acknowledged and agreed that an Unvested Share may not
be the subject of a Sale. In connection with any Sale of the Shares, WFH shall
make appropriate arrangements to timely release such Shares from the Pledge, so
as to allow the sale to occur in the normal course, so long as, as of the date
GBM requests the release of such Shares from the Pledge, the Fair Market Value
of the Shares which will remain subject to the Pledge (after giving effect to
the Shares requested to be released from the Pledge) is at least 125% of the
outstanding principal and accrued interest remaining due under the Revised GBM
Note (after giving effect to the payment of the Specified Share Price to be made
by GHM to WFH for each Share included in the Sale). GBM and WFH agree that the
5,660,000 Vested Subordinate Voting Shares in respect of which a certificate or
certificates were not delivered pursuant to s.3 may be the subject of a Sale
and GBM agrees that on or before June 30, 2001 he will pay the Specified Share
Price in respect thereof to WFH or will deliver the certificate or certificates
representing such Shares to WFH to be held pursuant to the Pledge.

GBM PUT

6. Upon the occurrence of any of the events specified below, GBM or any
Permitted Transferee shall have the right to sell all or any portion of his
Vested Shares or Unvested Shares, to WFH (the "GBM PUT") as set forth below:

         (a) if GBM ceases to be employed by 360 for any reason, GBM or any
         Permitted Transferee or, upon the death of either GBM or any Permitted
         Transferee, his or her beneficiary, shall at any time after such date
         of termination be entitled to exercise the GBM Put:

                  (i) with respect to any Vested Share at a per Share price
                  equal to the Market Value of the Shares calculated as of the
                  Exercise Date; and

                  (ii) with respect to any Unvested Share at a per Share price
                  equal to the lesser of

                           (A) the Market Value of a Share calculated as of the
                           Exercise Date or

                           (B) the Specified Share Price per Share;

         provided, however, that the aggregate number of Shares that may be put
         to WFH pursuant to clause (i) or clause (ii) shall not at any time
         exceed the Aggregate Put Amount Limit;

         (b) during GBM's employment by 360, GBM or any Permitted Transferee or,
         upon the death of either GBM or any Permitted Transferee, his or her
         beneficiary, shall be entitled to exercise the GBM Put with respect to
         any Vested Share at a per Share price

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         equal to the Market Value of the Shares calculated as of the Exercise
         Date; provided, however, that the aggregate amount of Shares that may
         be put to WFH pursuant to this s.6(b) shall not exceed the Aggregate
         Put Amount Limit;

         (c) the closing (the "CLOSING") of any purchase and sale of Shares to
         be effected as a result of GBM's exercise of the GBM Put shall take
         place at the offices of WFH at 11:00 a.m. (Pacific Coast Time) on the
         fifth business day (the "CLOSING DATE") following the later of

                  (i) the Exercise Date, and

                  (ii) in the event that Subordinate Voting Shares are not
                  Listed Securities on the Exercise Date, the date upon which
                  the Valuation Firm determines the Fair Market Value,

         or upon such other date and/or at such other time upon which WFH and
         GBM may agree in writing;

         (d) at the Closing of any purchase and sale of Shares pursuant to or as
         a result of GBM's exercise of the GBM Put, subject always to the
         set-off provisions contained herein:

                  (i) in the event the Subordinate Voting Shares are Listed
                  Securities on the Exercise Date, WFH shall deliver by wire
                  transfer of immediately available U.S. funds to an account
                  designated by GBM (A) if GBM is exercising the GBM Put in
                  respect of that number of Shares that is equal to the
                  Aggregate Put Amount Limit, an amount equal to the product
                  obtained by multiplying such number of Shares by the Market
                  Value thereof calculated in accordance with paragraphs (b) and
                  (c) of the definition of Fair Market Value, or in accordance
                  with the definition of Alternative Fair Market Value (Listed
                  Securities), as the case may be, or (B) if GBM is exercising
                  the GBM Put in respect of that number of Shares that is less
                  than the Aggregate Put Amount Limit, an amount equal to the
                  product obtained by multiplying such number of shares by the
                  Market Value thereof calculated in accordance with paragraphs
                  (b) and (c) of the definition of Fair Market Value, or in
                  accordance with the definition of Alternative Fair Market
                  Value (Listed Securities), as the case may be, and GBM shall
                  deliver the certificate representing the Shares being
                  purchased and sold pursuant to the exercise of the GBM Put;
                  and

                  (ii) in the event the Subordinate Voting Shares are not Listed
                  Securities on the Exercise Date, WFH shall deliver by wire
                  transfer of immediately available U.S. funds to an account
                  designated by GBM (A) if GBM is exercising the GBM Put in
                  respect of that number of Shares that is equal to the
                  Aggregate Put Amount Limit, an amount equal to the product
                  obtained by multiplying such number of Shares by the Fair
                  Market Value thereof calculated in accordance with paragraphs
                  (a) and (c) of the definition of Fair Market Value, or (B) if
                  GBM is exercising the GBM Put in respect of that number of
                  Shares that is less than the Aggregate Put Amount Limit, an
                  amount equal to the product obtained by multiplying such

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                  number of shares by the Fair Market Value thereof calculated
                  in accordance with paragraphs (a) and (c) of the definition of
                  Fair Market Value, and GBM shall deliver the certificate
                  representing the Shares being purchased and sold pursuant to
                  the exercise of the GBM Put.

GBM confirms and agrees that the GBM Put on the terms and conditions described
herein is WFH's sole obligation with respect to any put right GBM has as of the
date hereof or ever has had.

SHARES SUBJECT TO THE REPURCHASE RIGHT

7. The parties acknowledge that 360 continues to have the Repurchase Right. So
long as WFH continues to hold Shares pursuant to the Pledge, WFH will hold the
Unvested Shares in escrow for 360 to permit 360 to exercise its Repurchase
Right. For the purposes of establishing WFH's obligation herein, 360 and GBM
covenant to deliver to WFH a Certificate monthly after each release of Unvested
Shares to GBM. If 360 exercises its Repurchase Right with respect to any
Unvested Shares held by WFH pursuant to the Pledge, 360 will pay the purchase
price pursuant to the Repurchase Right so exercised to WFH if and to the extent
of any amounts remaining due under the Revised GBM Note, and otherwise to GBM,
and such payment, if made to WFH, will fulfil 360's payment obligation to GBM
with respect to the Repurchase Right so exercised. The amount of such payment if
made to WFH will be applied by WFH as a payment on the Revised GBM Note.

VOTING OF SHARES

8. As long as the Shares that are represented by the share certificates are held
pursuant to this Agreement, GBM shall be entitled to vote such Shares and be
entitled, subject to s.9, to all rights and privileges of a shareholder of 360.

STOCK DIVIDEND

9. If any stock dividend or other distribution of shares is paid or made on or
in respect of any of the Shares represented by the share certificates included
in the Collateral Documents while such share certificates are held pursuant to
this Agreement, GBM will, forthwith upon his receipt thereof, deliver any share
certificates representing such stock dividend or distribution to WFH to be held
by WFH pursuant to the provisions of this Agreement, and WFH will accept such
share certificates in this regard.

GBM RIGHT TO SETOFF.

10. Notwithstanding anything contained herein to the contrary, GBM shall have
the right (but not the obligation), at his sole discretion, to deliver Shares to
WFH pursuant to the GBM Put and elect that any amount owed to him by WFH (or any
assignee) as a result of the GBM Put automatically reduce the amount owed by GBM
under the Revised GBM Note by an equal amount. Without limiting the generality
of the foregoing, in the event that GBM exercises the GBM Put and WFH (or any
assignee) fails to honor its obligations in accordance with the terms hereof,
then GBM shall have the right (but not the obligation), at his sole discretion,
to reduce the amount due under the Revised GBM Note by any amount that would
have been paid

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                                     - 11 -

to GBM if WFH (or such assignee) had honored its obligations under the GBM Put,
and the Shares so attempted to be put shall be transferred to WFH.

WFH RIGHT TO SETOFF

11. Notwithstanding anything contained herein to the contrary, if GBM exercises
the GBM Put and delivers Shares to WFH (or its assignee), WFH (or its assignee)
shall have the right (but not the obligation), at its sole discretion, to
discharge amounts owed to GBM under the GBM Put, up to the full amount remaining
due under the Revised GBM Note, by cancelling the amount owed by GBM under the
Revised GBM Note. The right of WFH (or its assignee) under this s.11 shall not
be limited or affected by any mortgage, pledge or charge over the Revised GBM
Note created by or pursuant to the general security agreement dated as of April
22, 2001 granted by WFH to 360finance ltd.

CONDITIONS FOR WFH OBLIGATIONS

12. The obligations of WFH under s.5 and s.6 shall be conditional upon the
receipt by WFH of a Certificate, dated not more than two days prior to the
closing of a Sale or the Closing Date, as the case may be, which confirms that
GBM has a sufficient number of Vested Shares or Unvested Shares to effect the
transaction contemplated by the applicable paragraph.

COVENANT OF WFH

13. So long as the Revised GBM Note is outstanding , WFH agrees with GBM that:

         (a) it will not engage in any business other than the direct or
         indirect holding or disposing of shares in 360 and Urbanlink Holdings
         Ltd. (and, in either case, successors); and

         (b) it will not create any indebtedness other than indebtedness in the
         ordinary course for day-to-day operating expenses including for
         professional fees, other indebtedness to affiliates which is
         subordinate to all other indebtedness and the note to 360finance ltd.
         referred to in recital D.

WFH OBLIGATIONS WITH REGARD TO IRS FORM W-8 BEN

14. With respect to the Revised GBM Note, WFH will provide a duly executed IRS
Form W-8 BEN and a statement that WFH is not a bank within the meaning of
section 881(c)(3)(A) of the Internal Revenue Code of 1986, as amended (the
"Code"), or a controlled foreign corporation within the meaning of section
881(c)(3)(C) of the Code and that WFH intends to claim exemption from U.S.
Federal withholding tax under section 881(c) of the Code. WFH shall indicate
whether it is entitled to treaty benefits on such Form W-8 BEN. WFH shall
deliver such Form W-8 BEN to GBM within thirty (30) days after WFH's acquisition
of the Revised GBM Note. WFH represents that it is not a U.S. person (as such
term is defined in section 7701(a)(30) of the Code) and agrees that it will
deliver to GBM new, accurate and complete forms or documentation prescribed by
applicable law if such forms and documentation are required to be updated so as
to permit interest payments to be made without withholding tax or at a reduced
rate of withholding tax.

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NOTICE

15. Any notice, request, direction or other instrument required or permitted to
be given hereunder by any party to another will be deemed to be well and
sufficiently given if in writing and delivered by hand (including commercial
courier service) to the applicable party at the applicable address set out in
the initial pages of this Agreement or to such other address as is specified by
the particular party by notice to each other party hereto.

DEEMED RECEIPT

16. Any notice delivered as aforesaid will be deemed conclusively to have been
effectively given and received on the day such notice was delivered as
aforesaid, if it was delivered by hand (including commercial courier).

GENDER AND NUMBER

17. In this Agreement, words importing the masculine gender include the feminine
or neuter, words in the singular include the plural, words importing a corporate
entity include individuals and vice versa.

SEVERABILITY

18. If one or more provisions of this Agreement are held to be unenforceable
under applicable law, the parties agree to renegotiate such provision in good
faith. In the event that the parties cannot reach a mutually agreeable and
enforceable replacement for such provision, then such provision will be enforced
to the maximum extent possible and the other provisions will remain fully
effective and enforceable, but only to the extent that such enforcement does not
fundamentally alter the intent of the parties as evidenced by this Agreement.

GOVERNING LAW

19. This Agreement is and will be deemed to have been made in the Province of
British Columbia, for all purposes will be governed exclusively by and construed
in accordance with the laws prevailing in British Columbia and the laws of
Canada applicable therein, and the rights and remedies of the parties hereto
will be determined in accordance with those laws.

ATTORNMENT

20. The parties hereto irrevocably attorn to the exclusive jurisdiction of the
courts of British Columbia and all courts having appellate jurisdiction
thereover, and agree that any proceeding commenced or maintained in respect of
or arising as a consequence of this Agreement will be commenced and maintained
only in such of those courts as is appropriate.

ENUREMENT; TRANSFER TO WFH SUBSIDIARY

21. This Agreement shall inure to the benefit of the successors and assigns of
WFH and 360 and, subject to the restrictions on transfer set forth in this
Agreement, be binding upon GBM, GBM's heirs, executors, administrators,
successors, and Permitted Transferees.

<PAGE>

                                     - 13 -

Notwithstanding anything contained in this Agreement to the contrary, WFH shall
not delegate any of its obligations hereunder without the prior written consent
of GBM, and any such delegation without GBM's written consent shall be void and
of no effect; provided that WFH may, with the consent of GBM which shall not be
unreasonably withheld, transfer its rights and obligations under this Agreement
to a wholly-owned subsidiary of WFH if WFH transfers the Revised GBM Note to
such subsidiary concurrently therewith. It shall not be unreasonable for GBM to
withhold his consent to any transfer if he is of the opinion, reasonably held,
that, as a result of such transfer, his rights and obligations under this
Agreement would be prejudiced or subject to risk which does not exist with
respect to WFH.

COUNTERPARTS

22. This Agreement may be executed by any party hereto and delivered, in
original form or by electronic facsimile, in several counterparts, each of which
together will be read and construed and will constitute one and the same
instrument as if all of the parties hereto executed the same document.

<PAGE>

                                     - 14 -

IN WITNESS WHEREOF the parties have executed and delivered this Agreement on the
day and year first above written.

Signed
---------------------------------------
GREGORY B. MAFFEI

WORLDWIDE FIBER HOLDINGS LTD.

Per: Signed____________________________
     Authorized Signatory

360 NETWORKS INC.

Per: Signed____________________________
     Authorized Signatory<PAGE>

                                                                 EXHIBIT 4.28

                                360NETWORKS INC.

                  AMENDED AND RESTATED STOCK PURCHASE AGREEMENT

                  THIS AMENDED AND RESTATED STOCK PURCHASE AGREEMENT (the
"Agreement") is made as of the 22nd day of April, 2001 (the "Effective Date"),
by and between 360NETWORKS INC., a corporation continued under the laws of Nova
Scotia (the "Company"), and GREGORY B. MAFFEI (the "Purchaser") (collectively,
the "Parties"). This Agreement is an amended and restated version of the Stock
Purchase Agreement made as of December 22, 1999 between the Company and the
Purchaser (the "Original Stock Purchase Agreement"), a copy of which is attached
as Schedule A. The parties acknowledge and agree that the Original Stock
Purchase Agreement set forth the complete and exclusive terms and conditions of
the agreement between the parties with respect to the subject matter thereof for
the period commencing on December 22, 1999 and ending on the date hereof.

                                    RECITALS

                  WHEREAS, the Company and the Purchaser have entered into an
Employment Agreement, dated December 22, 1999, pursuant to which the Company has
agreed to employ the Purchaser, and the Purchaser has agreed to serve as the
President and Chief Executive Officer of the Company (the "Employment
Agreement"); and

                  WHEREAS, the Company issued, and Purchaser acquired, stock of
the Company as herein described, on the terms and conditions hereinafter set
forth.

                  NOW, THEREFORE, IT IS AGREED between the Parties as follows:

         Section 1 PURCHASE AND SALE OF STOCK. On December 22, 1999, Purchaser
purchased from the Company, and the Company sold to Purchaser, an aggregate of
thirty one million (31,000,000) shares of common stock of the Company (as of the
date of this Agreement, such shares have become sixty two million (62,000,000)
shares), of which twenty six million eighty thousand (26,080,000) shares were
Class A Non-voting Shares of the Company (the "Class A Shares") (as of the date
of this Agreement, such shares have become fifty two million, one hundred sixty
thousand (52,160,000) Subordinate Voting Shares) and four million nine hundred
twenty thousand (4,920,000) shares were Class C Multiple Voting Shares of the
Company (the "Class C Shares") (as of the date of this Agreement, such shares
have become nine million, eight hundred forty thousand (9,840,000) Multiple
Voting Shares) (collectively, the "Shares"), at two dollars and fifty cents
(U.S. $2.50) per share (the "Purchase Price Per Share") (as of the date of this
Agreement, equivalent to US $1.25 per currently issued share), for an aggregate
purchase price of seventy seven million five hundred thousand dollars (U.S.
$77,500,000) (the "Purchase Price"). The Purchase Price was paid by certified
check or wire transfer. The Company caused its affiliate 360finance ltd. to lend
the Purchase Price to Purchaser against delivery of a promissory note payable to
360finance ltd. in the form attached hereto at TAB 1. The closing hereunder,
including the loan of the Purchase Price and payment for and delivery of the
Shares, has occurred.

<PAGE>

         Section 2 REPURCHASE OPTION.

                  (a) REPURCHASE OPTION. In the event Purchaser's employment by
the Company, (A) terminates for any or no reason, or (B) [Clause deleted.] then
the Company shall have an irrevocable option (the "Repurchase Option"), which
shall be exercisable during the ninety (90) day period after said termination or
such longer period as may be agreed to by the Company and the Purchaser in
writing, to repurchase from Purchaser for the Option Price, subject to
adjustment pursuant to Section 2(d), that number of Shares that have not ceased
to be subject to the Repurchase Option in accordance with the provisions of
Section 2(b) below as of such termination date.

                  (b) LAPSE OF REPURCHASE OPTION.

                      (i) GENERAL PROVISIONS. Seventy five percent (75%) of the
Shares, all of which will be Class A Shares, shall initially be subject to the
Repurchase Option and, therefore, 7,750,000 Shares (as of the date of this
Agreement, post-split, 15,500,000 Shares), of which 4,920,000 Shares will be
Class C Shares (as of the date of this Agreement, 9,840,000 Multiple Voting
Shares) and 2,830,000 Shares will be Class A Shares (as of the date of this
Agreement, 5,660,000 Subordinate Voting Shares), became immediately vested upon
the execution of the Original Stock Purchase Agreement and will never be subject
to the Repurchase Option; [Clause deleted]. Subject to the provisions of Section
2(b)(ii) and Section 2(b)(iii) of this Agreement, the Shares that are initially
subject to the Repurchase Option shall cease to be subject to the Repurchase
Option according to the following schedule, provided that the Purchaser is
employed by the Company (or a parent or subsidiary of the Company) on such date:

------------------------------------------ ------------------------------------
                    Date                    Number of Shares that cease to be
                                            subject to the Repurchase Option
------------------------------------------ ------------------------------------
             December 22, 2000                           6,200,000
                                              (12,400,000 post-split shares)
    The last day of each calendar month                   568,332
        following December 22, 2000            (1,136,664 post-split shares)
------------------------------------------ ------------------------------------

                      (ii) CHANGE OF CONTROL PROVISIONS. Notwithstanding the
preceding provisions of Section 2(b)(i): (A) upon the occurrence of a Change of
Control, 40% of the remaining unvested Shares shall cease to be subject to the
Repurchase Option (i.e., the Repurchase Option shall lapse on such date with
respect to 40% of the Shares that remain subject to the Repurchase Option
immediately prior to such date), and (B) if at any time during the two-year
period immediately following the occurrence of a Change of Control, Purchaser
ceases for any reason other than a termination of service or employment by the
Company or its successor for Cause pursuant to Section 5(a) of the Employment
Agreement or by the Executive without Good Reason pursuant to Section 5(d) of
the Employment Agreement, to be (1) a member of the Board of the surviving
entity, and/or (2) the President and/or Chief Executive Officer of the surviving
entity on terms that are at least as favorable as the then current terms of the
Employment Agreement, then 100% of the remaining unvested Shares shall cease to
be subject to the Repurchase Option (i.e., the Repurchase Option shall lapse in
its entirety on the date Purchaser ceases to be the President, Chief Executive
Officer, or a member of the Board of the surviving entity).

                                     - 2 -
<PAGE>

                      (iii) TERMINATION OF EMPLOYMENT WITHOUT CAUSE OR FOR GOOD
REASON. Notwithstanding the preceding provisions of Section 2(b)(i), upon the
earliest to occur of: (a) the date that Purchaser's employment is terminated by
the Company without Cause pursuant to Section 5(d) of the Employment Agreement;
or (b) the date that Purchaser's employment is terminated as a result of his
death or Disability pursuant to Section 5(b) of the Employment Agreement, or (c)
the date the Purchaser terminates his employment with the Company for Good
Reason pursuant to Section 5(c) of the Employment Agreement (clauses (a), (b)
and (c) each being a "Termination Event" and, collectively, the "Termination
Events"), [Clause deleted] twenty two percent (22%) of the Shares will cease to
be subject to the Repurchase Option.

         (c) EXERCISE OF REPURCHASE OPTION. The Repurchase Option shall be
exercised by written notice signed by an officer of the Company or by any
assignee or assignees of the Company and delivered or mailed as provided in
Section 19(a). Such notice shall identify the number of Shares to be purchased
and shall notify Purchaser of the time, place and date for settlement of such
purchase, which shall be scheduled by the Company within thirty (30) days of
receipt of such notice. The Company, or any assignee or assignees of the
Company, shall, at its or their option, pay for any Shares purchased pursuant to
the Repurchase Option by certified check, by payment to the party specified
pursuant to the Master Agreement dated April 22, 2001 (the "Master Agreement")
and made between the Company, Purchaser and Worldwide Fiber Holdings Ltd. Upon
delivery of such notice and payment of the purchase price in any of the ways
described above, the Company, or any assignee or assignees of the Company (as
applicable), shall become the legal and beneficial owner of the Shares being
repurchased and all rights and interest therein or related thereto, and the
Company shall have the right to transfer to its own name or the name of any
assignee or assignees of the Company the Shares being repurchased by the
Company, or any assignee or assignees of the Company without further action by
Purchaser.

         (d) ADJUSTMENTS TO STOCK. If, from time to time, during the term of
the Repurchase Option there is any change affecting the outstanding Stock as a
class that is effected without the receipt of consideration by the Company
(through merger, consolidation, reorganization, reincorporation, stock dividend,
dividend in property other than cash, stock split, liquidating, dividend,
combination of shares, change in corporate structure or other transaction not
involving the receipt of consideration by the Company), then any and all new,
substituted or additional securities or other property which Purchaser receives
and/or to which Purchaser is entitled by reason of Purchaser's ownership of
Shares shall be immediately subject to the Repurchase Option and be included in
the word "Shares" for all purposes of the Repurchase Option with the same force
and effect as the Shares currently subject to the Repurchase Option, but only to
the extent the Shares are, at the time, covered by such Repurchase Option. While
the total Option Price shall remain the same after each such event, the Option
Price per Share upon exercise of the Repurchase Option shall be appropriately
adjusted.

         (e) TERMINATION OF REPURCHASE OPTION. Section 2 of this Agreement
shall terminate upon the exercise in full or expiration of the Repurchase
Option, whichever first occurs.

                                     - 3 -
<PAGE>

         (f) ASSIGNMENT. The Repurchase Option hereunder shall be
assignable by the Company at any time or from time to time, in whole or in part.

     Section 3 [DELETED.]

     Section 4 DEMAND REGISTRATION RIGHTS.

         (a) REQUEST FOR REGISTRATION. Subject to Section 4(b) of this
Agreement, Purchaser shall be entitled to make a written request ("Demand
Registration Request") to the Company for registration with the Commission under
and in accordance with the provisions of the Securities Act of all or part of
the Shares owned by him (a "Demand Registration") (which Demand Registration
Request shall specify the intended number of Shares to be disposed of by
Purchaser and the intended method of disposition thereof); provided, that the
Company may, if the Board so determines in the exercise of its reasonable, good
faith judgment that due to a pending or contemplated acquisition or disposition
or public offering or other similar occurrence it would be inadvisable to effect
such Demand Registration at such time, defer such Demand Registration for a
single period not to exceed one hundred eighty (180) days; provided, however, in
the event that the Company proposes to register shares of its stock under the
Securities Act, whether or not for sale for its own account, during such single
period, Purchaser shall have the right to exercise his Incidental Registration
Rights as outlined in Section 5 of this Agreement with respect to such
registration. Within ten (10) days after receipt of such request, the Company
will use its best efforts to effect the registration under the Securities Act of
the Shares which the Company has been so requested to register by Purchaser.

         (b) NUMBER OF DEMAND REGISTRATIONS. At any time on or after September
7, 2001, Purchaser shall be entitled to make one Demand Registration Request at
any time; PROVIDED, that (i) the number of Shares subject to any such Demand
Registration represents at least twenty five percent (25%) of the number of
Shares held, directly or indirectly, by Purchaser immediately prior to his
Demand Registration Request, (ii) the Company shall not be obligated to effect
more than one Demand Registration AND (iii) Purchaser shall not be entitled to
make a Demand Registration Request during any period during which (A) all of the
Shares may be freely transferred at the same time pursuant to Rule 144
promulgated under the Securities Act, or (B) all of the Shares have been
properly registered on a registration statement, such registration statement is
effective under the Securities Act and all of the Shares may be freely
transferable pursuant to such registration statement.

         (c) EFFECTIVE REGISTRATION AND EXPENSES. A registration will not count
as a Demand Registration until it has become effective (unless Purchaser
withdraws the Shares, in which case such demand will count as a Demand
Registration unless Purchaser agrees to pay all Registration Expenses). The
Company shall be solely responsible for any and all costs and expenses of all
registrations and qualifications under the Securities Act, and of all other
actions the Company is required to take in order to effect the registration of
Shares under the Securities Act whether pursuant to this Agreement or otherwise.

         (d) PRIORITY ON DEMAND REGISTRATIONS. If the offering of Purchaser's
Shares pursuant to such Demand Registration is in the form of an underwritten
offering and the managing underwriter or underwriters of such offering advise
the Company and Purchaser in

                                     - 4 -
<PAGE>

writing that in their opinion the number of Shares requested to be included in
such offering is sufficiently large to adversely affect the success of such
offering, the Company will include in such registration the aggregate number of
shares which in the opinion of such managing underwriter or underwriters can be
sold without any such adverse effect, and such amount shall be allocated in the
following order of priority: (i) first, the Shares of the Purchaser subject to
any such Demand Registration and (ii) second, any shares of common stock that
the Company or any other holder proposes to sell.

     Section 5 INCIDENTAL REGISTRATION RIGHTS. As of December 22, 1999, the
Company, certain shareholders of the Company and the Purchaser entered into a
Joinder to the Shareholders Agreement substantially in the form attached hereto
at TAB 5, which provides that for purposes of Section 2.2 and all related
Sections of the Registration Rights Agreement, Purchaser shall constitute, and
shall be entitled to all of the benefits, rights and features associated with
being, a "Holder of record of Registrable Securities."

     Section 6 COMMITMENT TO REGISTER SHARES. As soon as permitted under the
Securities Act following an IPO, the Company will register the Shares purchased
or otherwise acquired by the Purchaser pursuant to this Agreement on a Form S-8
and/or such other form as may be required to permit the sale of such Shares then
held by Purchaser or any "permitted transferee," within the meaning of Form S-8
and/or any other applicable form, in the public market without any restriction,
other than restrictions that arise from the volume limitations of Rule 144.

     Section 7 ADDITIONAL REGISTRATION RIGHTS. If at any time, whether before
or after the Effective Date, the Company has granted or grants to any individual
or entity (an "Additional Investor") rights to register under an effective
registration statement pursuant to the Securities Act any shares of common stock
owned, directly or indirectly, by such Additional Investor, then the Company
shall also grant such registration rights to Purchaser with respect to any
Shares to the extent that such registration rights granted to such Additional
Investor in any way exceed, supplement, or otherwise provide increased benefit
or protection to such Additional Investor than the registration rights granted
to Purchaser under Sections 4, 5 or 6 of this Agreement; provided, that, the
Company will not grant registration rights to any Additional Investor unless
approved by the Board.

     Section 8 [Deleted.]

     Section 9 ESCROW OF UNVESTED STOCK. As security for Purchaser's faithful
performance of the terms of this Agreement and to insure the availability for
delivery of Shares upon exercise of the Repurchase Option herein provided for,
Purchaser agrees, immediately upon receipt of the Stock certificate(s)
evidencing the Shares, to deliver to and deposit with Worldwide Fiber Holdings
Ltd. or a corporate trustee selected pursuant to the process provided in the
Master Agreement ("Escrow Agent"), as Escrow Agent in this transaction, three
(3) Stock assignments duly endorsed (with date and number of shares blank) in
the form attached hereto at TAB 2, together with a certificate or certificates
evidencing all of the Shares subject to the Repurchase Option; said documents
are to be held by the Escrow Agent and delivered by said Escrow Agent pursuant
to the Master Agreement. As Shares cease to be subject to the Repurchase Option,
they shall be dealt with in the manner provided in the Master Agreement.

                                     - 5 -
<PAGE>

     Section 10 RIGHTS OF PURCHASER. Subject to the provisions of Sections 3,
4, 5, 6, 7 or 8 of this Agreement, Purchaser shall exercise all rights and
privileges of a stockholder of the Company with respect to the Shares from and
after the date that Purchaser delivered payment of the Purchase Price until such
time as Purchaser disposes of the Shares or the Company, or any assignee or
assignees of the Company, exercises its or their right to repurchase the Shares
pursuant to Section 2 of this Agreement. Purchaser shall be deemed to be the
holder for purposes of receiving any dividends that may be paid with respect to
such Shares and for the purpose of exercising any voting rights relating to such
Shares, even if some or all of such Shares have not yet vested and been released
from the Repurchase Option.

     Section 11 LIMITATIONS ON TRANSFER. In addition to any other limitation on
transfer created by applicable securities laws, Purchaser shall not assign,
hypothecate, donate, encumber or otherwise dispose of any interest in the Shares
while the Shares are subject to the Repurchase Option. After any Shares have
been released from the Repurchase Option, Purchaser shall not assign,
hypothecate, donate, encumber or otherwise dispose of any interest in the Shares
except in compliance with the provisions of this Agreement and applicable
securities laws. Notwithstanding anything to the contrary in this Section and to
the extent permitted by applicable securities laws, the following transfers of
shares will be exempt from this Section 11: (i) the transfer of any or all of
the Shares during Purchaser's lifetime by gift or on Purchaser's death by will
or intestacy to a Permitted Transferee (as defined below), provided that each
Permitted Transferee agrees in a writing satisfactory to the Company that such
Permitted Transferee will not transfer, or permit any transfer, of the equity in
such Permitted Transferee to any entity other than one that also constitutes a
Permitted Transferee; (ii) any transfer of Shares made pursuant to a statutory
merger or statutory consolidation of the Company with or into another
corporation or corporations (except that the right of first refusal will
continue to apply thereafter to such Shares, in which case the surviving
corporation of such merger or consolidation shall succeed to the rights of the
Company under this Section 11 unless the agreement of merger or consolidation
expressly provides otherwise); (iii) any transfer of Shares, pursuant to the
winding up and dissolution of the Company; or (iv) any transfer of Shares to the
Company or any assignee or assignees of the Company, in accordance with Sections
2 and 8 of this Agreement.

     Section 12 RESTRICTIVE LEGENDS. All certificates representing the Unvested
Shares shall have endorsed thereon legends in substantially the following forms
(in addition to any other legend which may be required by other agreements
between the Parties hereto, including the Shareholders Agreement):

                (a) "THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO
AN OPTION SET FORTH IN AN AGREEMENT BETWEEN THE COMPANY AND THE REGISTERED
HOLDER, OR SUCH HOLDER'S PREDECESSOR IN INTEREST, A COPY OF WHICH IS ON FILE AT
THE PRINCIPAL OFFICE OF THIS COMPANY. ANY TRANSFER OR ATTEMPTED TRANSFER OF ANY
SHARES SUBJECT TO SUCH OPTION IS VOID WITHOUT THE PRIOR EXPRESS WRITTEN CONSENT
OF THE COMPANY."

                (b) "THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933 AS

                                     - 6 -
<PAGE>

AMENDED. THEY MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN THE
ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT AS TO THE SECURITIES UNDER SAID
ACT OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION
IS NOT REQUIRED."

                (c) "THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO
A RIGHT OF FIRST REFUSAL OPTION IN FAVOR OF THE COMPANY AND/OR ITS ASSIGNEE(S)
AS PROVIDED IN THE BYLAWS OF THE COMPANY."

                (d) Any legend required by applicable blue sky laws.

     Section 13 REPRESENTATIONS OF THE COMPANY. The Company hereby represents
and warrants to the Purchaser as of December 22, 1999 as follows:

                (a) ORGANIZATION, GOOD STANDING AND QUALIFICATION. The Company
is a corporation duly organized, validly existing and in good standing under the
laws of Nova Scotia. The Company has all requisite corporate power and authority
to execute and deliver this Agreement, to issue and sell the Shares, and to
carry out the provisions of this Agreement.

                (b) CAPITALIZATION. As of December 22, 1999, the capitalization
of the Company is set forth at TAB 4.

                (c) AUTHORIZATION; BINDING OBLIGATIONS. All corporate action on
the part of the Company necessary for the authorization of this Agreement, the
performance of all obligations of the Company hereunder at the closing and the
authorization, sale, issuance and delivery of the Shares pursuant hereto have
been taken prior to the closing. The Agreement, when executed and delivered,
will be valid and binding obligations of the Company enforceable in accordance
with their terms, except (i) as limited by applicable bankruptcy, insolvency,
reorganization, moratorium or other laws of general application affecting
enforcement of creditors' rights, and (ii) general principles of equity that
restrict the availability of equitable remedies. The sale of the Shares are not
and will not be subject to any preemptive rights or rights of first refusal that
have not been properly waived or complied with.

     Section 14 SECTION 83(B) ELECTION. The Parties acknowledge that Purchaser
has filed or will file an election under Section 83(b) of the Internal Revenue
Code of 1986, as amended, (the "Code") with respect to his purchase of the
Shares hereunder and has reported or will report in such election that the
purchase price for the Shares is equal to the fair market value of the Shares
(determined without regard to restrictions that will lapse) at the time of
transfer. The Parties shall not voluntarily take (and the Parties shall cause
their respective affiliates not to voluntarily take) any tax reporting position
that is inconsistent with such Section 83(b) election, including the valuation
of the Shares. Purchaser assumes all responsibility for filing the Section 83(b)
election and paying all of Purchaser's taxes resulting from such election or the
lapse of the restrictions on the Shares. Purchaser acknowledges that the Company
is not responsible for any tax obligation of the Purchaser regardless of his
filing an election under Section 83(b) with respect to his purchase of the
Shares.

                                     - 7 -
<PAGE>

     Section 15 PROVISIONS REGARDING PROMISSORY NOTE. With respect to the
promissory note of Purchaser provided for under Section 1 of this Agreement, the
Company has provided or will provide or has caused or shall cause 360finance
ltd. to provide an IRS Form W-8 BEN and a statement that 360finance ltd. is not
a bank within the meaning of section 881(c)(3)(A) of the Code or a controlled
foreign corporation within the meaning of section 881(c)(3)(C) of the Code and
intends to claim exemption from U.S. Federal withholding tax under section
881(c) of the Code. The Company shall also indicate or cause 360finance ltd. to
indicate whether it is entitled to treaty benefits on such Form W-8 BEN. The
Company has provided or shall provide or cause 360finance ltd. to provide a duly
executed Form W-8 BEN to Purchaser within thirty (30) days after Purchaser's
execution of the promissory note. The Company represents, as of December 22,
1999, that neither it nor 360finance ltd. is a U.S. person (as such term is
defined in section 7701(a)(30) of the Code) and agrees that it will deliver or
cause 360finance ltd. to deliver to Purchaser new, accurate and complete forms
or documentation prescribed by applicable law if such forms and documentation
are required to be updated so as to permit such payments to be made without
withholding tax or at a reduced rate of withholding tax.

     Section 16 REFUSAL TO TRANSFER. The Company shall not be required (a) to
transfer on its books any Shares which shall have been transferred in violation
of any of the provisions set forth in this Agreement or (b) to treat as owner of
such Shares or to accord the right to vote as such owner or to pay dividends to
any transferee to whom such shares shall have been so transferred.

     Section 17 NO EMPLOYMENT RIGHTS. This Agreement is not an employment
contract and nothing in this Agreement shall affect in any manner whatsoever the
right or power of the Company (or a parent or subsidiary of the Company) to
terminate Purchaser's employment for any reason at any time, with or without
Cause and with or without notice.

     Section 18 DEFINITIONS. As used in this Agreement the following terms
shall have the following respective meanings:

             "Board" shall mean the Company's Board of Directors.

             "Cause" shall have the meaning set forth in Section 5(f)(i) of the
Employment Agreement.

             "Change of Control" shall have the meaning set forth in Section
5(f)(ii) of the Employment Agreement.

             "Commission" shall mean the Securities and Exchange Commission.

             "Disability" shall have the meaning set forth in Section 5(f)(iii)
of the Employment Agreement.

             "Exercise Date" shall mean the date on which the Company
purchases Shares from the Purchaser pursuant to the Purchaser's exercise of his
Put under Section 8 of this Agreement.

                                     - 8 -
<PAGE>

             "Good Reason" shall have the meaning set forth in Section 5(f)(iv)
of the Employment Agreement.

             "Investor Securities" shall mean any stock or other securities
of the Company held by any Investor.

             "IPO" shall have the meaning set forth in the Shareholders
Agreement.

             "Option Price" means, with respect to one (1) Share, the sum of:
(A) the Purchase Price Per Share with respect to such Share AND (B) interest
thereon from and including December 22, 1999, at a rate equal to 6.20% per
annum, compounded annually on December 21 in each year thereafter.

             "Permitted Transferee" shall mean: (i) Purchaser's spouse or
children or grandchildren (in each case, natural or adopted), (ii) any trust
established solely for such Purchaser's benefit or the benefit of such
Purchaser's spouse or children or grandchildren (in each case, natural or
adopted), (iii) any corporation or partnership in which the direct and
beneficial owner of all of the equity interest is such individual Purchaser or
such Purchaser's spouse or children or grandchildren (in each case, natural or
adopted) (or any trust for the benefit of such persons) or (iv) the heirs,
executors, administrators or personal representatives upon the death of
Purchaser or upon the incompetency or disability of Purchaser for purposes of
the protection and management of the assets of the Purchaser.

             "Registration Rights Agreement" shall mean the Registration
Rights Agreement by and among Worldwide Fiber Inc., DWF SRL, GSCP3 WWF
(Barbados) SRL, WWF (Barbados) SRL, Providence Equity Fiber, L.P., Tyco Group
S.A.R.L., dated as of September 9, 1999.

             "Securities Act" shall mean the Securities Act of 1933, as amended.

             "Shareholders Agreement" shall mean the Shareholders Agreement
by and among Worldwide Fiber Inc., DWF SRL, GS Capital Partners III, L.P., GSCP3
WWF (Barbados) SRL, WWF (Barbados) SRL, Providence Equity Fiber, L.P., Tyco
Group S.A.R.L., Worldwide Fiber Holdings Ltd., Ledcor Inc., and The Several
Shareholders Named in Schedule I, dated as of September 9, 1999, as amended to
reflect the transaction(s) contemplated by this Agreement and the Employment
Agreement. (The Shareholders Agreement, as so defined, was amended and restated
by an Amended and Restated Shareholders Agreement dated as of April 20, 2000.)

             "Vested Shares" are Shares that have never been (i.e., all of
the Class C Shares) or have otherwise ceased to be subject to the Repurchase
Option.

             "Unvested Shares" are Shares that, as of a given date, remain
subject to the Repurchase Option.

     Section 19 MISCELLANEOUS.

                (a) NOTICES. Any notice required or permitted hereunder shall
be given in writing and shall be deemed effectively given upon personal delivery
or facsimile

                                     - 9 -
<PAGE>

transmission, three (3) days after deposit in the United States mail, certified
or registered mail (return receipt requested), or one (1) business day after its
deposit with any express courier (prepaid), addressed to the other party hereto
at his address (or facsimile number, in the case of transmission by facsimile)
hereinafter shown below its signature to this Agreement or to such other address
(or facsimile number) as such party may designate by ten (10) days' advance
written notice to the other party hereto.

                (b) SUCCESSORS AND ASSIGNS. This Agreement shall inure to the
benefit of the successors and assigns of the Company and, subject to the
restrictions on transfer herein set forth, be binding upon Purchaser,
Purchaser's heirs, executors, administrators, successors, and assigns.

                (c) GOVERNING LAW; VENUE. This Agreement shall be governed by
and construed in accordance with the laws of the State of Washington. The
Parties agree that any action brought by either party to interpret or enforce
any provision of this Agreement shall be brought in, and each party agrees to,
and does hereby, submit to the jurisdiction and venue of, the appropriate state
or federal court for the district encompassing Seattle, Washington.

                (d) FURTHER EXECUTION. The Parties agree to execute such further
instruments and to take all such further action(s) as may reasonably be
necessary to carry out and consummate the purpose and intent of this Agreement.

                (e) ENTIRE AGREEMENT; AMENDMENT. This Agreement and each of the
Tabs thereto, the Employment Agreement and each of the Exhibits thereto,
constitute the entire agreement between the Parties with respect to the subject
matter of this Agreement and supersedes and merges all prior agreements or
understandings, whether written or oral. This Agreement may not be amended,
modified or revoked, in whole or in part, except by an agreement in writing
signed by each of the Parties hereto.

                (f) SEVERABILITY. If one or more provisions of this Agreement
are held to be unenforceable under applicable law, the Parties agree to
renegotiate such provision in good faith. In the event that the Parties cannot
reach a mutually agreeable and enforceable replacement for such provision, then
such provision will be enforced to the maximum extent possible and the other
provisions will remain fully effective and enforceable.

                (g) COUNTERPARTS. This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original and all of which
together shall constitute one instrument.

                (h) HEADINGS. The captions and headings of this Agreement are
included for ease of reference only and will be disregarded in interpreting or
construing this Agreement. Unless specifically indicated otherwise, all
references herein to Sections will refer to Sections of this Agreement.

                      [THIS SPACE INTENTIONALLY LEFT BLANK]

                                     - 10 -
<PAGE>

                  In Witness Whereof, the Parties hereto have executed this
Agreement as of the day and year first above written.

                                       360NETWORKS INC.

                                       Signed
                                       _______________________________________
                                       Name:
                                       Title:

                                       PURCHASER:

                                       Signed
                                       _______________________________________
                                       Gregory B. Maffei

ATTACHMENTS:

     Tab 1 --       Promissory Note
     Tab 2 --       Stock Assignment Separate from Certificate
     Tab 3 --       Deleted
     Tab 4 --       The Company's Capitalization
     Tab 5 --       Deleted

     Schedule A     Original Stock Purchase Agreement

                                     - 11 -

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