EXHIBIT 99.1

ADVANCED INSTRUCTION TO SELL COMMON STOCK

To: Deutsche Bank Alex. Brown
    A Division of Deutsche Bank Securities Inc.

Account Number:

     I am a holder of shares, or options to acquire shares, of the common stock
("Common Stock") of Ligand Pharmaceuticals, Inc. (the "Company"). I would like
to periodically sell Company shares in order to diversify my portfolio. I also
wish to take advantage of Rule 10b5-1 under the Securities Exchange Act of 1934,
as amended, which provides for an affirmative defense from insider trading
liability for purchases and sales effected pursuant to a contract, instruction
or plan entered into when a person is not aware of any material nonpublic
information. This instruction ("Instruction") is intended to constitute a
"written plan for trading securities" within the meaning of Rule 10b5-1.

     I hereby instruct Deutsche Bank Securities Inc. (referred to herein as
"Deutsche Bank Alex. Brown") to sell 70,000 shares of Common Stock AND exercise
options representing 50,000 shares of Common Stock, and sell the resulting
shares of Common Stock pursuant to the specific instructions set forth in
Schedules A and B hereto OR as follows:

     You are authorized to make deliveries of securities and payment of moneys
in accordance with your normal practice. All shares to be sold shall have been
previously deposited into my account, and you shall not be required to follow
this Instruction if shares are not present in my account (or acceptable
arrangements to deliver option shares have not been made) prior to the dates on
which sales shall occur. If this Instruction requires you to exercise stock
options you shall do so in accordance with your normal procedures, and unless
instructed otherwise, remit the exercise price and the withholding tax as
calculated by the Company. In no instance should you exercise options that are
not in the money. The share amount listed above shall be increased or decreased
to reflect stock splits should they occur. I understand that I shall be
responsible to arrange for any filings that may be required under applicable law
(e.g., Form 144, Schedule 13D, and Forms 4 and 5), and that I may be subject to
the short swing profit rules contained in Section 16 of the Securities Exchange
Act of 1934. In this connection, I understand that upon my request, you will
assist me in making advance arrangements regarding the filing of Forms 144.

     All sales shall be effected in your normal fashion in accordance with your
terms and conditions for my account and risk. You may act as principal in any
transaction hereunder. I understand that you may not be able to make all of the
sales contemplated under this Instruction due to a market disruption or a legal,
regulatory or contractual restriction applicable to you or any other event or
circumstance. I further understand that even in the absence of such a
circumstance, you may be unable to make sales consistent with ordinary
principles of best execution due to insufficient volume of trading or other
market factors in effect on the date of a sale. I hereby ratify and confirm any
and all transactions with you in accordance with this Instruction. I also agree
to indemnify and hold Deutsche Bank Alex. Brown harmless from and to pay
Deutsche Bank Alex. Brown promptly on demand any and all losses arising from its
reasonable interpretation and performance of this Instruction.

     You will cease making sales under this Instruction as soon as practicable
following receipt of written notice from the Company, confirmed by telephone,
that the Company has entered into a transaction that results in my being subject
to trading restrictions. You shall resume making sales in accordance with this
Instruction as soon as practicable after you receive written notice from the
Company of the cessation or termination of any such trading restriction. Any
sales not made as a result of the imposition of any trading restriction shall be
sold in the next following selling period.

     While this Instruction is in effect I will not enter into or alter any
corresponding or hedging transaction or position with respect to the Common
Stock (including any securities convertible or exchangeable into Common Stock).
I agree that until this Instruction has been terminated I will not enter into a
binding contract with respect to the purchase or sale of Common Stock with
another broker, dealer or financial institution, instruct any broker, dealer or
financial institution to purchase or sell Common Stock or adopt a trading plan
with respect to Common Stock other than this Instruction.




     I represent and warrant that I am not presently aware of any material
nonpublic information regarding the Company or its securities and that I am
currently able to sell Common Stock under the Company's insider trading policies
and covenant that I will not discuss or otherwise disclose material nonpublic
information to my investment representative or any other of your personnel
responsible for carrying out this Instruction. I have obtained the approval of
the Company's counsel to enter into this Instruction.

     This Instruction may be modified, terminated or amended only by a writing
signed by the parties hereto. Any modification or amendment of this Instruction
may only occur at a time when I am not aware of material nonpublic information
concerning the Company or its securities and I am otherwise permitted to make
sales under the Company's insider trading policies. If this Instruction is
modified or amended, or if I establish a new plan after termination of this
Instruction, no sales shall be made during the thirty (30) calendar days
immediately following such modification, amendment or termination (other than
sales already provided for in the Instruction prior to modification, amendment
or termination).

     Deutsche Bank Alex Brown is authorized to begin selling Stock pursuant to
this Sales Plan on March 18, 2005, and shall cease selling Stock on the earliest
to occur of (i) the date on which Deutsche Bank Alex Brown is required to
suspend or terminate sales under the Sales Plan pursuant to the previous
paragraph, (ii) the date on which Deutsche Bank Alex Brown receives notice of
the death of Seller, (iii) the date on which the Issuer or any other person
publicly announces a tender or exchange offer with respect to the Stock or a
merger, acquisition, reorganization, recapitalization or comparable transaction
affecting the securities of the Issuer as a result of which the Stock is to be
exchanged or converted into shares of another company, (iv) the date on which
Deutsche Bank Alex Brown receives notice of the commencement or impending
commencement of any proceedings in respect of or triggered by Seller's
bankruptcy or insolvency and (v) the earlier of

     December 31,2005 or

     the date that the aggregate number of shares of Stock sold pursuant to
     this Sales Plan reaches shares specified on Schedules A and B

     This Instruction shall not be effective until Deutsche Bank Alex. Brown
confirms its acceptance in writing by signing below. It shall remain in full
force and effect until revoked or modified by me in writing. Deutsche Bank Alex.
Brown may decline to act hereunder upon reasonable notice. I hereby irrevocably
authorize you to accept any instruction from the Company to cease or suspend
sales hereunder.



/S/ MARK A. RADOVANOVICH                    /S/ DAVID E. ROBINSON
                                            ---------------------
                                            Signature of Customer

- -------------------------------------------------------------------------------
Accepted
Deutsche Bank Alex. Brown

MARK A. RADOVANOVICH
Branch Manager
Dated: 12-10-04
Rule10b5 - 1Form.AdvancedInstructionstoSell.12.9.04




/S/ CLIFFORD G. WANG

CLIFFORD G. WANG





                                   SCHEDULE A
                             (Shares Owned Outright)

Name of Seller  David E. Robinson         Seller's Social Security # __________
Daytime Tel. #:___________Cellular:__________Fax #: ________Email: ____________

SALE OF OWNED STOCK


- --------------------------------------------- -------------------------- -----------------------------
a.                                            b.                         c.
Designated Sale Period                        Authorized Number of       Net Limit Price ($) or
From                     To                   Owned Shares               "Market" Price (select one):
- ----------------------- --------------------- -------------------------- -----------------------------
                                                                
June 1, 2005            September 30, 2005    35,000 shares              $15.00/share
- ----------------------- --------------------- -------------------------- -----------------------------

October 1, 2005         December 31, 2005     35,000 shares              $20.00/share
- ----------------------- --------------------- -------------------------- -----------------------------


- ----------------------- --------------------- -------------------------- -----------------------------


- ----------------------- --------------------- -------------------------- -----------------------------


- ----------------------- --------------------- -------------------------- -----------------------------


- ----------------------- --------------------- -------------------------- -----------------------------


- ----------------------- --------------------- -------------------------- -----------------------------

                                              --------------------
                                              |   70,000 shares  |
                                              --------------------


1.   INSTRUCTIONS: In column (a), state the first and last date on which the
     Shares are authorized to be sold during the Designated Sale Period (Stock
     sales may occur on or between these dates). The "To" column may be left
     blank in which case the Designated Sale Period will last until this
     Instruction terminates.

     In column (b), state the maximum number of shares authorized to be
     sold at the designated price during the Designated Sale Period. Do not
     aggregate with amounts authorized to be sold at a lower price during the
     same Designated Sale Period.

     In column (c), write either (i) a dollar price which is the minimum
     price (the "Net Limit Price") at which Stock is authorized to be sold, or
     (ii) the word "market" if Stock is to be sold at the then-prevailing market
     price per share during the Designated Sale Period. If a Net Limit Price is
     instructed, I understand that my order(s) will be executed only when
     Deutsche Bank Alex. Brown can sell at a price equal or higher than my
     minimum price(s) plus the mark-up.

2.   I X am (_____ am not) subject to Rule 144 filing requirements and, if
     applicable, I have provided signed documents to be filed on my behalf.





                                   SCHEDULE B

                                 (Stock Options)

Name of Seller  David E. Robinson         Seller's Social Security # __________
Daytime Tel. #:___________Cellular:__________Fax #: ________Email: ____________


    EXERCISE OF OPTIONS AND SALE OF STOCK OBTAINED UPON EXERCISE OF OPTIONS.

(Please note: Seller represents that the information below is accurate. You may
use multiple lines to apportion shares in a grant across differing Sales Periods
or Limit Prices. Each line will be treated as a distinct trading instruction.).


- ---------------- ------------ ------------ -------------- ------------ --------------------- ------------------- -------------------
                 a.           b.           c.             d.           e.                    f.                  g.
                                                          Vesting      Designated Sale       Authorized Number   Net Limit Price $
Line             Grant ID #   Date of      Strike         Date For     Period                of Option Shares
                              Grant        Price          Unvested
                                                          Shares       From      To
- ---------------- ------------ ------------ -------------- ------------ ---------- ---------- ------------------- -------------------
                                                                                          
       1         B92628       3/11/95      $6.75/SHARE    ISO *        3/18/05    3/22/05          15,625        Initiate
                                                          Vested                                                 exercise/sell if at
                                                                                                                 least $.25 above
                                                                                                                 strike price
- ---------------- ------------ ------------ -------------- ------------ ---------- ---------- ------------------- -------------------
       2         BM92628      3/22/95      $6.75/SHARE    NQ* Vested   3/18/05    3/22/05          34,375        Initiate
                                                                                                                 exercise/sell  if
                                                                                                                 at least $.25 above
                                                                                                                 strike price
- ---------------- ------------ ------------ -------------- ------------ ---------- ---------- ------------------- -------------------
       3

- ---------------- ------------ ------------ -------------- ------------ ---------- ---------- ------------------- -------------------
       4

- ---------------- ------------ ------------ -------------- ------------ ---------- ---------- ------------------- -------------------
       5

- ---------------- ------------ ------------ -------------- ------------ ---------- ---------- ------------------- -------------------
       6

- ---------------- ------------ ------------ -------------- ------------ ---------- ---------- ------------------- -------------------
       7

- ---------------- ------------ ------------ -------------- ------------ ---------- ---------- ------------------- -------------------
*3/22/99                                                                     --------------------
                                                                             |  Total:50,000    |
                                                                             --------------------


INSTRUCTIONS:

1.   In columns (a) and (b), list the Options which are to be exercised.

     In column (c), specify the applicable strike price.

     In column (d) specify the applicable vesting date.




     In column (e), state the first and last date on which the option is
     authorized to be exercised and sold during the Designated Sale Period
     (Exercises and sales may occur on or between these dates). The "To" column
     may be left blank in which case the Designated Sale Period will last until
     this Instruction terminates.

     In column (f), state the maximum number of Option Shares to be
     exercised.

     In column (g), write the dollar price which is the minimum price (the
     "Net Limit Price") at which the Authorized Number of Option Shares is
     authorized to be sold. If a Net Limit Price is instructed, I understand
     that my order(s) will be executed only when Deutsche Bank Alex. Brown sells
     at a price equal or higher than my minimum price(s) plus the mark-up.

2.   In the event that Deutsche Bank Alex. Brown is unable to sell the
     Authorized Number of Option Shares in a Designated Sale Period for any
     reason: (check one of the following instructions)

     X the unsold amount of Option Shares will be carried forward and added
     to the Authorized Number of Option Shares for each succeeding Designated
     Sale Period until sold at the original net limit price; or

     ___ the unsold amount of Option Shares will not be sold and will not
     be carried over to the next Designated Sale Period.

3.   I X am (_____ am not) subject to Rule 144 filing requirements and, if
     applicable, I have provided signed documents to be filed on my behalf.

I recognize that if the nature of the above listed options changes materially,
including but not limited to my termination, I will notify Deutsche Bank Alex.
Brown immediately.