UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                 ---------------

                                    FORM 8-A


                FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES
                    PURSUANT TO SECTION 12(B) OR 12(G) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


                       LIGAND PHARMACEUTICALS INCORPORATED
             (Exact Name of Registrant as Specified in Its Charter)


                   DELAWARE                               77-0160744
     (State of Incorporation or Organization)         (I.R.S. Employer
                                                     Identification No.)

          10275 SCIENCE CENTER DRIVE                      92121-1117
            SAN DIEGO, CALIFORNIA                         (Zip Code)
            (Address of Principal
              Executive Offices)

  If this form relates to the              If this form relates to the
  registration of a class of securities    registration of a class of securities
  pursuant to Section 12(b) of the         pursuant to Section 12(g) of the
  Exchange Act and is effective            Exchange Act and is effective
  pursuant to General Instruction          pursuant to General Instruction
  A.(c), please check the following        A.(d), please check the following
  box. |X|                                 box.

Securities Act registration statement file number to which this form relates:

         Securities to be registered pursuant to Section 12(b) of the Act:

       Title of Each Class                    Name of Each Exchange on Which
       TO BE SO REGISTERED                    EACH CLASS IS TO BE REGISTERED

 Preferred Share Purchase Rights                   NASDAQ Global Market


Securities to be registered pursuant to Section 12(g) of the Act:

                                      None
                                (Title of Class)








                 INFORMATION REQUIRED IN REGISTRATION STATEMENT

ITEM 1.  DESCRIPTION OF REGISTRANT'S SECURITIES TO BE REGISTERED.

            In connection with the expiration of the Amended and Restated
Preferred Shares Rights Agreement dated September 13, 1996, as amended, between
Ligand Pharmaceuticals Incorporated (the "COMPANY") and Mellon Investor Services
LLC ("MELLON"), as Rights Agent, which associated rights (as defined therein)
expired on September 13, 2006, the Board of Directors of the Company approved a
new 2006 Preferred Shares Rights Agreement (the "2006 RIGHTS AGREEMENT") with
Mellon as Rights Agent. As of October 13, 2006, the Board of Directors of the
Company declared a dividend of one right (a "RIGHT" or "RIGHTS") to purchase one
one-thousandth share of the Company's Series A Participating Preferred Stock
("SERIES A PREFERRED") for each outstanding share of Common Stock, par value
$0.001 per share ("COMMON SHARES"), of the Company. The dividend is payable on
October 31, 2006 (the "RECORD DATE") to stockholders of record as of the close
of business on that date. Each Right entitles the registered holder to purchase
from the Company one one-thousandth of a share of Series A Preferred at an
exercise price of $100 (the "PURCHASE PRICE"), subject to adjustment as
described below. The description and terms of the Rights are set forth in the
2006 Rights Agreement.

            Initially, the Rights will be attached to all certificates
representing shares of Common Shares then outstanding, and no separate
certificates evidencing the Rights ("RIGHTS CERTIFICATES") will be distributed.
Common Share certificates issued after the Record Date but prior to the
Distribution Date (as defined below) will contain a notation incorporating the
2006 Rights Agreement by reference. The Rights will separate from the Common
Shares, Rights Certificates will be issued and the Rights will become
exercisable upon the earlier of: (i) 10 days (or such later date as may be
determined by the Company's Board of Directors) following a public announcement
that a person or group of affiliated or associated persons (an "ACQUIRING
PERSON") has acquired, or obtained the right to acquire, beneficial ownership of
20% or more of the outstanding Common Shares, or (ii) 10 days (or such later
date as may be determined by the Company's Board of Directors) following the
commencement of, or announcement of an intention to make, a tender offer or
exchange offer the consummation of which would result in the beneficial
ownership by a person or group of 20% or more of the outstanding Common Shares.
The earlier of such dates is referred to as the "DISTRIBUTION DATE."

            Until the Distribution Date (or earlier redemption, exchange or
expiration of the Rights), the surrender or transfer of any certificates for
Common Shares, even without notation or a copy of the Summary of Rights being
attached thereto (but as to certificates representing Common Shares issued after
the Record Date, only if they bear the legend required by the 2006 Rights
Agreement), will also constitute the transfer of the Rights associated with the
Common Shares represented by such certificate. As soon as practicable following
the Distribution Date, separate Rights Certificates will be mailed to holders of
record of the Common Shares as of the close of business on the Distribution Date
and such separate Rights Certificates alone will evidence the Rights from and
after the Distribution Date.

            The holders of the Rights are not required to take any action until
the Rights become exercisable. As described above, the Rights are not
exercisable until the Distribution Date. Holders of the Rights will be notified
that the Rights have become exercisable when the Rights Agent mails the Rights
Certificates. The Rights will expire on October 13, 2016 (the "FINAL EXPIRATION
DATE"), unless earlier redeemed, exchanged or terminated under the terms of the
2006 Rights Agreement.

            The Purchase Price payable, the number of Rights and the number of
Series A Preferred or Common Shares or other securities or property issuable
upon exercise of the Rights are subject to adjustment from time to time in the
event the Company declares a dividend payable in Common Shares, subdivides the
number of outstanding Common Shares into a larger number of such shares or
combines the number of outstanding Common Shares into a smaller number of such
shares, among other circumstances, as set forth in the 2006 Rights Agreement.
With certain exceptions, no adjustment in the Purchase Price will be required
unless such adjustment would require an increase or decrease of at least 1% in
the Purchase Price.

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            Because of the nature of the dividend, liquidation and voting
rights, the value of the one one-thousandth interest in a share of Series A
Preferred purchasable upon exercise of each Right should approximate the value
of one Common Share. Series A Preferred purchasable upon exercise of the Rights
will not be redeemable. Each share of Series A Preferred will be entitled to an
aggregate dividend of 1,000 times the dividend declared per Common Share. In the
event of liquidation, the holders of the Series A Preferred will be entitled to
a minimum preferential liquidation payment equal to $1,000 per share. Each share
of Series A Preferred will have 1,000 votes, voting together with the Common
Shares. In the event of any merger, consolidation or other transaction in which
the Common Shares are changed or exchanged, each share of Series A Preferred
will be entitled to receive 1,000 times the amount received per Common Share.
These rights are protected by customary anti-dilution provisions.

            In the event that, at any time following the date on which there has
been public disclosure that a person or group has become an Acquiring Person
(the "SHARES ACQUISITION DATE"), (i) the Company is acquired in a merger or
other business combination transaction, or (ii) 50% or more of the Company's
consolidated assets or earning power are sold (other than in transactions in the
ordinary course of business) (either of which event is referred to herein as an
"ACQUISITION"), proper provision shall be made so that each holder of a Right
which has not theretofore been exercised (other than Rights beneficially owned
by the Acquiring Person, which will thereafter be void) will thereafter have the
right to receive, upon exercise, shares of Common Stock of the acquiring company
having a value equal to two times the Purchase Price.

            At any time after the acquisition by an Acquiring Person of 20% or
more of the Company's outstanding Common Shares and prior to the acquisition by
such Acquiring Person of 50% or more of the Company's outstanding Common Shares,
the Board of Directors of the Company may exchange the Rights (other than Rights
owned by the Acquiring Person), in whole or in part, at an exchange ratio of one
Common Share per Right, subject to adjustment.

            At any time on or prior to the close of business on the earlier of
(i) the 10th day following the Shares Acquisition Date or such later date as may
be determined by the Company's Board of Directors and publicly announced by the
Company, or (ii) the Final Expiration Date of the Rights, the Company may redeem
the Rights in whole, but not in part, at a price of $0.01 per Right (the
"REDEMPTION PRICE"). The redemption of the Rights may be made effective at such
time, on such basis and with such conditions as the Board of Directors in its
sole discretion may establish. Immediately upon any redemption of the Rights,
the right to exercise the Rights will terminate and the only right of the
holders of Rights will be to receive the Redemption Price.

            Until a Right is exercised, the holder thereof, as such, will have
no rights as a stockholder of the Company (other than any rights resulting from
such holder's ownership of Common Shares), including, without limitation, the
right to vote or to receive dividends.

            The provisions of the 2006 Rights Agreement may be supplemented or
amended by the Board of Directors in any manner prior to the close of business
on the Distribution Date without the approval of the Rights holders. After the
Distribution Date, the provisions of the 2006 Rights Agreement may be amended by
the Board in order to cure any ambiguity, defect or inconsistency, to make
changes which do not adversely affect the interests of holders of Rights
(excluding the interests of any Acquiring Person), or to shorten or lengthen any
time period under the 2006 Rights Agreement; provided, however, that no
amendment to adjust the time period governing redemption shall be made at such
time as the Rights are not redeemable.

            A copy of the 2006 Rights Agreement, which includes as Exhibit A the
form of Rights Certificate, is attached as Exhibit 4.1 to this Registration
Statement and incorporated herein by reference. This summary description of the
Rights does not purport to be complete and is qualified in its entirety by
reference to the 2006 Rights Agreement.

ITEM 2.  EXHIBITS.

         The document listed below is filed as an exhibit to this Registration
Statement:

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EXHIBIT NUMBER                              EXHIBIT TITLE
______________                              _____________

   4.1                    2006 Preferred Shares Rights Agreement, dated as of
                          October 13, 2006, between Ligand Pharmaceuticals
                          Incorporated and Mellon Investor Services LLC, as
                          Rights Agent, including the form of Rights Certificate
                          as Exhibit A and the Summary of Rights as Exhibit B



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                                    SIGNATURE

         Pursuant to the requirements of Section 12 of the Securities Exchange
Act of 1934, the registrant has duly caused this registration statement to be
signed on its behalf by the undersigned, thereto duly authorized.


Dated:  October 17, 2006    LIGAND PHARMACEUTICALS INCORPORATED


                            By:      /s/  Warner R. Broaddus
                                     -----------------------------------
                            Name:    Warner R. Broaddus
                            Title:   Vice President, General Counsel & Secretary

                                      5





                              EXHIBIT INDEX



EXHIBIT
 NUMBER                       EXHIBIT TITLE
________                      _____________

  4.1                    2006 Preferred Shares Rights Agreement, dated as of
                         October 13, 2006, between Ligand Pharmaceuticals
                         Incorporated and Mellon Investor Services LLC, as
                         Rights Agent, including the form of Rights Certificate
                         as Exhibit A and the Summary of Rights as Exhibit B



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