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                                                                   EXHIBIT 10.11


                             STOCK PLEDGE AGREEMENT


         THIS STOCK PLEDGE AGREEMENT ("PLEDGE AGREEMENT") is made by ULI
HACKSELL, an individual with a residence at 10819 Bonjon Lane, San Diego,
California 92131 ("PLEDGOR"), in favor of ACADIA PHARMACEUTICALS INC., a
Delaware corporation with its principal place of business at 3911 Sorrento
Valley Boulevard, San Diego, California ("PLEDGEE").

         WHEREAS, Pledgor has concurrently herewith executed that certain
Secured Promissory Note (the "NOTE") in favor of Pledgee in the amount of One
Hundred Thousand Dollars ($100,000); and

         WHEREAS, Pledgee is willing to accept the Note from Pledgor, but only
upon the condition, among others, that Pledgor shall have executed and delivered
to Pledgee this Pledge Agreement and the Pledged Collateral (as defined below);

         NOW, THEREFORE, in consideration of the foregoing recitals and for
other good and valuable consideration, the receipt and adequacy of which are
hereby acknowledged, and intending to be legally bound, Pledgor hereby agrees as
follows:

         1.       As security for the full, prompt and complete payment and
performance when due (whether by stated maturity, by acceleration or otherwise)
of all indebtedness of Pledgor to Pledgee created under the Note, together with,
without limitation, the prompt payment of all expenses, including, without
limitation, reasonable attorneys' fees and legal expenses, incidental to the
collection of the foregoing and the enforcement or protection of Pledgee's lien
in and to the collateral pledged hereunder (all such indebtedness being the
"LIABILITIES"), Pledgor hereby pledges to Pledgee, and grants to Pledgee, a
first priority security interest in all of the following (collectively, the
"PLEDGED COLLATERAL"):

                  (a)      all shares of the capital stock of Pledgee owned by
Pledgor pursuant to Pledgor's exercise or rights under any stock option plan or
otherwise (the "PLEDGED SHARES"), and all dividends, cash, instruments and other
property or proceeds from time to time received, receivable or otherwise
distributed in respect of or in exchange for any or all of the Pledged Shares;
and

                  (b)      all voting trust certificates held by Pledgor
evidencing the right to vote any Pledged Shares subject to any voting trust.

         Immediately following acquisition of the Pledged Shares, Pledgor agrees
to deliver to Pledgee the stock certificates representing said Pledged Shares
along with an executed but otherwise uncompleted Assignment Separate From
Certificate in the form attached hereto as Exhibit A.

         The term "indebtedness" is used herein in its most comprehensive sense
and includes any and all advances, debts, obligations and liabilities
heretofore, now or hereafter made, incurred or created, whether voluntary, or
involuntary, and whether due or not due, absolute or contingent,


                                       1.
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liquidated or unliquidated, determined or undetermined, and whether recovery
upon such indebtedness may be or hereafter becomes unenforceable.

         2.       Pledgor hereby represents and warrants to Pledgee that as of
the date that the stock certificates representing the Pledged Shares are
delivered by Pledgor to Pledgee:

                  (a)      Pledgor shall be the sole holder of record and the
sole beneficial owner of the Pledged Collateral, free and clear of any lien
thereon or affecting title thereto, except for the lien created by this Pledge
Agreement.

                  (b)      None of the Pledged Shares will have been transferred
in violation of securities registration, securities disclosure or similar laws
of any jurisdiction to which such transfer may be subject with respect to which
such transfer could have a material adverse effect.

                  (c)      No consent, approval, authorization or other order of
any person and no consent or authorization of any governmental authority or
regulatory body is required to be made or obtained by Pledgor either (i) for the
pledge by Pledgor of the Pledged Collateral pursuant to this Pledge Agreement or
for the execution, delivery, or performance of this Pledge Agreement by Pledgor;
or (ii) for the exercise by Pledgee of the voting or other rights provided for
in this Pledge Agreement or the remedies in respect of the Pledged Collateral
pursuant to this Pledge Agreement, except as may be required in connection with
such disposition by laws affecting the offering and sale of securities
generally.

                  (d)      The pledge, grant of a security interest in, and
delivery of the Pledged Collateral pursuant to this Pledge Agreement, will have
created a valid first priority lien on and in the collateral pledged by Pledgor,
and the proceeds thereof, securing the payment of the Liabilities.

                  (e)      This Pledge Agreement will have been duly executed
and delivered by Pledgor and will constitute a legal, valid, and binding
obligation of Pledgor enforceable in accordance with its terms, except as
enforceability may be limited by bankruptcy, insolvency, or other similar laws
affecting the rights of creditors generally or by the application of general
equity principles.

         Pledgor covenants, warrants, and represents to Pledgee that all
representations and warranties contained in this Pledge Agreement shall be true
at the time the stock certificates representing the Pledged Shares are delivered
by Pledgor to Pledgee and shall continue to be true until the Liabilities have
been paid or otherwise satisfied in full.

         3.       At time, without notice, and at the expense of Pledgor,
Pledgee in its name or in the name of its nominee or of Pledgor may, but shall
not be obligated to: (1) collect by legal proceedings or otherwise all dividends
(except cash dividends other than liquidating dividends), interest, principal
payments and other sums now or hereafter payable upon or on account of said
Pledged Collateral; (2) enter into any extension, reorganization, deposit,
merger or consolidation agreement, or any agreement in any way relating to or
affecting the Pledged Collateral, and in connection therewith may deposit or
surrender control of such Pledged Collateral thereunder, accept other property
in exchange for such Pledged


                                       2.
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Collateral and do and perform such acts and things as it may deem proper, and
any money or property received in exchange for such Pledged Collateral shall be
applied to the indebtedness or thereafter held by it pursuant to the provisions
hereof; (3) insure, process and preserve the Pledged Collateral; (4) cause the
Pledged Collateral to be transferred to its name or to the name of its nominee;
and (5) exercise as to such Pledged Collateral all the rights, powers and
remedies of an owner, except that so long as no Event of Default (as defined in
the Note), exists under the Note and no default exists hereunder Pledgor shall
retain all voting rights as to the Pledged Shares.

         4.       Pledgor agrees to pay prior to delinquency all taxes, charges,
liens and assessments against the Pledged Collateral, and upon the failure of
Pledgor to do so, Pledgee at its option may pay any of them and shall be the
sole judge of the legality or validity thereof and the amount necessary to
discharge the same.

         5.       Pledgor agrees that Pledgor:

                  (a)      will not (1) sell, transfer or otherwise dispose of,
or grant any option or warrant with respect to, any of the Pledged Collateral
(or any part thereof or interest therein) except with the prior written consent
of Pledgee, or (2) create or permit to exist any lien or encumbrance upon or
with respect to any of the Pledged Collateral. If any Pledged Collateral, or any
part thereof, is sold, transferred or otherwise disposed of in violation of this
Section 5, the security interest of Pledgee shall continue in the Pledged
Collateral notwithstanding such sale, transfer or other disposition, and the
Pledgor will deliver any proceeds thereof to the Pledgee to be held as Pledged
Collateral hereunder.

                  (b)      shall, at Pledgor's own expense, promptly execute,
acknowledge, and deliver all such instruments and take all such actions as
Pledgee from time to time may reasonably request in order to ensure to Pledgee
the benefits of the lien in and to the Pledged Collateral intended to be created
by this Pledge Agreement.

                  (c)      shall maintain, preserve and defend the title to the
Pledged Collateral and the lien of Pledgee thereon against the claim of any
other person.

         6.       At the option of Pledgee and without necessity of demand or
notice, all or any part of the indebtedness of Pledgor shall immediately become
due and payable irrespective of any agreed maturity, upon the happening of any
of the following events: (1) failure to keep or perform any of the terms or
provisions of this Pledge Agreement; (2) the occurrence of an Event of Default
under the Note; or (3) the levy of any attachment, execution or other process
against the Pledged Collateral.

         7.       All advances, charges, costs and expenses, including
reasonable attorneys' fees, incurred or paid by Pledgee in exercising any right,
power or remedy conferred by this agreement, or in the enforcement thereof,
shall become a part of the indebtedness secured hereunder and shall be paid to
Pledgee by the undersigned immediately and without demand.

         8.       In the event of the nonpayment of any indebtedness when due,
whether by acceleration or otherwise, or upon the happening of any of the events
specified in paragraph 6, Pledgee may then, or at any time thereafter, at its
election, apply, set off, collect or sell in one or more sales, or take such
steps as may be necessary to liquidate and reduce to cash in the hands of
Pledgee in whole or in part, with or without any previous demands or demand of
performance or


                                       3.
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notice or advertisement, the whole or any part of the Pledged Collateral in such
order as Pledgee may elect, and any such sale may be made either at public or
private sale at its place of business or elsewhere, or at any broker's board or
securities exchange, either for cash or upon credit or for future delivery;
provided, however, that if such disposition is at private sale, then the
purchase price of the Pledged Collateral shall be equal to the public market
price then in effect, or, if at the time of sale no public market for the
Pledged Collateral exists, then, in recognition of the fact that the sale of the
Pledged Collateral would have to be registered under the Securities Act of 1933
and that the expenses of such registration are commercially unreasonable for the
type and amount of collateral pledged hereunder, Pledgee and Pledgor hereby
agree that such private sale shall be at a purchase price mutually agreed to by
Pledgee and Pledgor or, if the parties cannot agree upon a purchase price, then
at a purchase price established by a majority of three independent appraisers
knowledgeable of the value of such collateral, one named by Pledgor within 10
days after written request by the Pledgee to do so, one named by Pledgee within
such 10 day period, and the third named by the two appraisers so selected, with
the appraisal to be rendered by such body within 30 days after the appointment
of the third appraiser. The cost of such appraisal, including all appraisers'
fees, shall be charged against the proceeds of sale as an expense of such sale.
Pledgee may be the purchaser of any or all Pledged Collateral so sold and hold
the same thereafter in its own right free from any claim of Pledgor or right of
redemption. Demands of performance, notices of sale, advertisements and presence
of property at sale are hereby waived, and Pledgee is hereby authorized to sell
hereunder any evidence of debt pledged to it. Any sale hereunder may be
conducted by any officer or agent of Pledgee.

         9.       The proceeds of the sale of any of the Pledged Collateral and
all sums received or collected by Pledgee from or on account of such Pledged
Collateral shall be applied by Pledgee to the payment of expenses incurred or
paid by Pledgee in connection with any sale, transfer or delivery of the Pledged
Collateral, to the payment of any other costs, charges, attorneys' fees or
expenses mentioned herein, and to the payment of the indebtedness or any part
hereof, all in such order and manner as Pledgee in its discretion may determine.
Pledgee shall then pay any balance to Pledgor.

         10.      Upon the transfer of all or any part of the indebtedness
Pledgee may transfer all or any part of the Pledged Collateral and shall be
fully discharged thereafter from all liability and responsibility with respect
to such Pledged Collateral so transferred, and the transferee shall be vested
with all the rights and powers of Pledgee hereunder with respect to such Pledged
Collateral so transferred; but with respect to any Pledged Collateral not so
transferred Pledgee shall retain all rights and powers hereby given.

         11.      Until all indebtedness shall have been paid in full the power
of sale and all other rights, powers and remedies granted to Pledgee hereunder
shall continue to exist and may be exercised by Pledgee at any time and from
time to time irrespective of the fact that the indebtedness or any part thereof
may have become barred by any statute of limitations, or that the personal
liability of Pledgor may have ceased.

         12.      Pledgee may at any time deliver the Pledged Collateral or any
part thereof to Pledgor and the receipt thereof by Pledgor shall be a complete
and full acquittance for the Pledged Collateral so delivered, and Pledgee shall
thereafter be discharged from any liability or responsibility therefor.


                                       4.
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         13.      The rights, powers and remedies given to Pledgee by this
Pledge Agreement shall be in addition to all rights, powers and remedies given
to Pledgee by virtue of any statute or rule of law. Any forbearance, failure or
delay by Pledgee in exercising any right, power or remedy hereunder shall not be
deemed to be a waiver of such right, power or remedy, and any single or partial
exercise of any right, power or remedy hereunder shall not preclude the further
exercise thereof, and every right, power and remedy of Pledgee shall continue in
full force and effect until such right, power or remedy is specifically waived
by an instrument in writing executed by Pledgee.

         14.      If any provision of this Pledge Agreement is held to be
unenforceable for any reason, it shall be adjusted, if possible, rather than
voided in order to achieve the intent of the parties to the extent possible. In
any event, all other provisions of this Pledge Agreement shall be deemed valid
and enforceable to the full extent possible.

         15.      This Pledge Agreement shall be governed by, and construed in
accordance with, the laws of the State of California as applied to contracts
made and performed entirely within the State of California by residents of such
state.

Dated:  May 11, 2000                  PLEDGOR


                                      /s/  ULI HACKSELL
                                      -----------------
                                      ULI HACKSELL


                                       5.


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                                    EXHIBIT A

                      ASSIGNMENT SEPARATE FROM CERTIFICATE


         ULI HACKSELL hereby sells, assigns and transfers unto
________________________________ a total of ________________ (______) shares of
the ________________________________ stock of ACADIA PHARMACEUTICALS INC.,
standing in the undersigned's name on the books of said corporation represented
by Certificate Nos. _____________ delivered herewith and does hereby irrevocably
constitute and appoint ________________________________ to transfer said stock
on the books of said corporation with full power of substitution.


Dated:  ____________                    By:  /s/  ULI HACKSELL
                                             -----------------
                                             ULI HACKSELL