<PAGE>

                                                                   EXHIBIT 10.11

                           FOURTH AMENDMENT TO LEASE
                         Expansion of Leased Premises

     THIS FOURTH AMENDMENT TO THE LEASE is made this 21/st/ of February, 2000 by
and between Spieker Properties, L.P., a California Limited Partnership, (the
"Landlord") and Pointshare Corporation, a Washington corporation, (the
"Tenant").

     WHEREAS, Landlord and Tenant entered into a Lease Agreement dated February
3, 1999 (the "Lease") and amended thereafter for certain premises located at
1300 114th Ave. S.E., Bellevue, Washington 98004 (the "Premises"), as more fully
described in the Lease; and

     WHEREAS, Landlord and Tenant desire to expand the Premises and modify the
Lease accordingly;

     NOW THEREFORE, in consideration of the covenants and agreements contained
herein, the parties hereby mutually agree as follows:

1. PREMISES: Effective on March 1, 2000, the Premises shall include
   --------
   approximately 3,277 rentable square feet located in Suites 110 and 245 in
   that certain building commonly known as Mercer Canal Building "L", 1300
   114/th/ Avenue SE, Bellevue, Washington, as outlined in Exhibit B attached
   hereto, for a total of approximately 22,312 rentable square feet for Suites
   L/100, L/110, L/208, L/232, L/240, L/245, L/250 of the Mercer Canal Building
   and I/220 of the Conifer Building (hereinafter defined as the "Entire
   Premises").

   Effective on March 1, 2002, the Entire Premises shall consist of
   approximately 22,570 rentable square feet.

2. COMMENCEMENT DATE: The scheduled term commencement date for Suites L/110 and
   -----------------
   L/245 shall be March 1, 2000, as defined in Paragraph 24 of the Lease.

3. RENT: Effective on March 1, 2000, the Base Rent for the Entire Premises as
   ----
   defined in Paragraph 6 of the Lease shall be adjusted to reflect the
   following:

               03/01/00 - 08/31/00  $43,146.00 per month
               09/01/00 - 02/28/01  $46,411.00 per month
               03/01/01 - 02/28/02  $47,803.00 per month
               03/01/02 - 02/29/03  $50,005.00 per month
               03/01/03 - 02/28/04  $51,648.00 per month
               03/01/04 - 02/28/05  $52,969.00 per month

4. TENANT'S PROPORTIONATE SHARE OF PROJECT:
   ---------------------------------------

   Effective on March 1, 2000, Tenant's Proportionate Share of the Project shall
   be 4.824%.

   Effective on March 1, 2002, Tenant's Proportionate Share of the Project shall
   be 4.880%.

5. SECURITY DEPOSIT: Upon execution of this Fourth Amendment to Lease, Tenant
   ----------------
   shall deposit the sum of Eight Thousand Ninety and no/100 Dollars ($8,090.00)
   in accordance with provisions of Paragraph 19 of the Lease. Upon deposit by
   the Tenant of the sum herein required, the security deposit held by Landlord
   shall total Fifty-Two Thousand Eight Hundred Seventy-Four and no/100 Dollars
   ($52,874.00). Upon Tenant's deposit of Fifteen Thousand Two Hundred Thirty-
   Three and no/100 Dollars ($15,233.00) on or before September 1, 2000, as
   outlined in the First Amendment, the security deposit held by the Landlord
   shall total Sixty-Eight Thousand One Hundred Seven and no/100 Dollars
   ($68,107.00).

7. PARKING: Effective on March 1, 2000, Landlord will identify three (3)
   -------
   additional covered reserved parking stalls for Tenant's use at the Mercer
   Canal Building. Tenant shall pay Landlord $40.00 per month per additional
   covered stall as additional rent, subject to increase over the term of the
   Lease.

8. IMPROVEMENTS BY LANDLORD: Landlord shall deliver Suites L/110 and L/245 in
   ------------------------
   the Mercer Canal Building to Tenant in "as is" condition, except that
   Landlord shall provide the following tenant improvements to Suites L/110 and
   L/245 at Landlord's cost, utilizing building standard materials, finishes and
   colors, as follows:

     Suite L/110:
     -----------
     .  Create doorway between Suites 110 and 100 as shown on Exhibit C-1

     Suite L/245:
     -----------
     .  New carpet and rubber base
     .  New paint on all walls

                                  Page 1 of 2
<PAGE>

    Landlord shall provide any additional improvements not listed herein at
    Tenant's sole cost and expense and as specified in a space plan to be
    mutually approved by Landlord and Tenant and hereby incorporated into the
    Lease in the form of an Addendum to the Fourth Amendment to the Lease as
    necessary.

9.  SPACE PLANNING: Landlord, at Tenant's sole cost, will engage an
    --------------
    architectural firm for the preparation of any space plans and other
    drawings, along with City permits and approvals which the Landlord, in its
    sole discretion, determines to be necessary to do the space construction.

10. BROKER: Landlord and Tenant agree that no commission shall be due from
    ------
    Landlord to an outside party in connection with the Lease herein proposed
    and that both parties shall indemnify the other against any claims by an
    outside broker.

11. CONTINGENCY: Tenant acknowledges that Landlord has notified Tenant that
    -----------
    Suites L/110 and L/245 in the Mercer Canal Building are currently leased by
    third party tenants. This Lease is subject to Landlord regaining possession
    of Suites L/110 and L/245 from said third party tenants on terms and
    conditions satisfactory to Landlord in its sole discretion.

     Except as expressly modified above, all terms and conditions of the Lease
remain in full force and effect and are hereby ratified and confirmed.

LANDLORD:                               TENANT:
Spieker Properties, L. P.               Pointshare Corporation,
a California limited partnership        a Washington corporation
By:  Spieker Properties, Inc.,
     a Maryland corporation
Its: General Partner


/s/ Richard Gervais                     /s/ Christopher P. Dishman
--------------------------------        ----------------------------------
By:  Richard P. Gervais                 By:  Christopher P. Dishman
Its: Vice President                     Its: Vice President, Finance &
                                        Administration

Date:___________________________        Date:  2/24/00
                                             -----------------------------

Fourth Lease Amendment dated      Page 2 of 2
2/18/00
Pointshare Corporation
<PAGE>

STATE OF        Washington      )
               -----------------
                                ) ss.

COUNTY OF          King         )
               -----------------

     On this  24th  day of  February      , 2000 , personally appeared before me
             -------       ---------------    ---
Christopher P. Dishman    , to me known to be the Vice President, Finance of the
--------------------------                        ------------------------
corporation that executed the within and foregoing instrument, and acknowledged
said instrument to be the free and voluntary act and deed of said corporation,
for the uses and purposes therein mentioned, and on oath stated that __he was
authorized to execute said instrument and that the seal affixed (if any) is the
corporate seal of said corporation.

     IN WITNESS WHEREOF, I have hereunto set my hand and affixed my Official
Seal the day and year first above written.

                                /s/ Lisa Y. Leitner
                                ------------------------------------------------
                                Print Name: Lisa Y. Leitner
                                           -------------------------------------
           [SEAL]                          NOTARY PUBLIC in and for the State of
                                             Washington            , residing at
                                            -----------------------
                                             King County
                                            -----------------------------------.
                                My commission expires: May 23, 2002
                                                      --------------------------


STATE OF       ________________)

                               ) ss.

COUNTY OF      ________________)

     On this __________ day of ______________, 20__, personally appeared before
me Richard P. Gervais, to me known to be the Vice President of the corporation
that executed the within and foregoing instrument, and acknowledged said
instrument to be the free and voluntary act and deed of said corporation, for
the uses and purposes therein mentioned, and on oath stated that he was
authorized to execute this instrument and that the seal affixed (if any) is the
corporate seal of said corporation.


                                ________________________________________________

                                Print Name:_____________________________________

                                           NOTARY PUBLIC in and for the State of

                                            _______________________, residing at

                                            ___________________________________.

                                My commission expires:__________________________


Pointshare Corporation Lease Amendment dated 02/21/00 for Premises located at
Mercer Canal Building, Suites 110 and 245
<PAGE>

                                   EXHIBIT B
                                   ---------

                                   PREMISES
                 MERCER CANAL BUILDING "L", SUITES 110 and 245
                            POINTSHARE CORPORATION

Cross hatched portion outlined in red reflects the Premises as referenced in
Paragraph 1 of the Lease. As built condition may vary from plan. Not to scale.

                              [FIRST FLOOR PLAN]


                              [SECOND FLOOR PLAN]

                                                               Landlord ________

                                                               Tenant     CPD
                                                                        --------
<PAGE>

                                   EXHIBIT C
                                   ---------

                                 IMPROVEMENTS
                 MERCER CANAL BUILDING "L", SUITES 110 AND 245
                            POINTSHARE CORPORATION

A.   Landlord's Work
     ---------------

     Premises shall be delivered to Tenant in "As Is" condition, except that
     Landlord, at Landlord's sole cost and expense, shall provide certain
     improvements to be made in the Premises, as specifically described herein.
     Tenant agrees to provide Landlord with information and approvals as may be
     requested by Landlord in connection with Landlord's obligations pursuant to
     this paragraph, including, but not limited to, materials, locations,
     approvals and selections requested by Landlord from Tenant, on a timely
     basis and in a time frame consistent with Landlord's construction and
     delivery schedule. Notwithstanding anything contained herein to the
     contrary, Landlord shall not be responsible to move, furnish or install
     appliances, furniture, files, moveable partitions or systems furniture or
     office equipment to Tenant or the Premises. Landlord's work shall be
     completed utilizing Building Standard materials, finishes and colors.
     Landlord may re-use materials and/or supplies in its sole discretion.

     Improvements provided by Landlord shall consist of the following work in
     the Premises to be completed on a schedule determined by Landlord in its
     sole discretion (hereinafter referred to as "Landlord's Work"):

        Suite 110:
        ---------
        . Create doorway between Suites 110 and 100 as shown in Exhibit C-1

        Suite 245:
        ---------
        . New carpet and rubber base
        . New paint on all walls

B.   Tenant's Work
     -------------

     Landlord shall make reasonable efforts to coordinate with Tenant's
     construction project manager in scheduling installation of Tenant's cabling
     and telecom equipment by Tenant's contractors and/or employees in the
     Premises at Tenant's sole cost and expense (hereinafter referred to as
     "Tenant's Work"). Tenant shall obtain at its sole cost and expense, permits
     and other governmental approvals as may be required for the completion of
     Tenant's Work. Building permits and any other governmental approvals for
     Tenant's work shall be drawn separate and apart from those drawn by
     Landlord for completion of the tenant improvements. Tenant's Work shall not
     be performed under building permits or other approvals related to the work
     performed by Landlord. Tenant agrees not to interfere with or cause delay
     in the completion of tenant improvement work by Landlord and/or its
     contractors. Tenant, its employees and/or contractors shall not perform any
     Tenant's Work in the Premises without prior approval of Landlord. All such
     approved Tenant Work performed prior to the Lease Commencement Date shall
     be subject to all of the terms and conditions of the Lease except for the
     payment of Base Rent which shall not be due until the Commencement Date.
     Notwithstanding anything stated herein, if Tenant's Work causes a delay or
     otherwise increases the cost of Landlord's Work, Tenant shall reimburse
     Landlord for said costs on or before the Lease Commencement Date.

All improvements shall be subject to applicable codes, laws and other
governmental regulations which may apply.

Tenant's occupancy of the Premises shall be deemed acceptance of the Tenant
Improvements herein described and Landlord shall be deemed to have fulfilled its
obligations with respect to Tenant Improvements.

                                                               Landlord ________

                                                               Tenant     CPD
                                                                        --------
<PAGE>

                                  EXHIBIT C-1
                                  -----------

                                 IMPROVEMENTS
                     MERCER CANAL BUILDING "L", SUITE 110
                            POINTSHARE CORPORATION

                                 [FLOOR PLAN]








                                                                 Landlord ______

                                                                  Tenant   CPD
                                                                          ------