SYMYX TECHNOLOGIES 1999 EMPLOYEE STOCK PURCHASE PLAN

Exhibit 10.4

SYMYX TECHNOLOGIES

1999 EMPLOYEE STOCK PURCHASE PLAN

As Amended and Restated on April 12, 2007 and May 4, 2009

1.               Purpose .  The purpose of the Plan is to provide employees of the Company and its Designated Subsidiaries with an opportunity to purchase Common Stock of the Company through accumulated payroll deductions. It is the intention of the Company to have the Plan qualify as an “Employee Stock Purchase Plan” under Section 423 of the Internal Revenue Code of 1986, as amended. The provisions of the Plan, accordingly, shall be construed so as to extend and limit participation in a manner consistent with the requirements of that section of the Code.

2.               Definitions .

(a)             “ Board ” shall mean the Board of Directors of the Company or any committee thereof designated by the Board of Directors of the Company in accordance with Section 14 of the Plan.

(b)             “ Code ” shall mean the Internal Revenue Code of 1986, as amended.

(c)             “ Common Stock ” shall mean the common stock of the Company.

(d)             “ Company ” shall mean Symyx Technologies, a Delaware corporation, and any Designated Subsidiary of the Company.

(e)            “ Compensation ” shall mean all base straight time gross earnings and commissions, but exclusive of payments for overtime, shift premium, incentive compensation, incentive payments, bonuses and other compensation.

(f)             “ Designated Subsidiary ” shall mean any Subsidiary that has been designated by the Board from time to time in its sole discretion as eligible to participate in the Plan.

(g)            “ Employee ” shall mean any individual who is an Employee of the Company for tax purposes whose customary employment with the Company is at least twenty (20) hours per week and more than five (5) months in any calendar year. For purposes of the Plan, the employment relationship shall be treated as continuing intact while the individual is on sick leave or other leave of absence approved by the Company. Where the period of leave exceeds 90 days and the individual’s right to reemployment is not guaranteed either by statute or by contract, the employment relationship shall be deemed to have terminated on the 91st day of such leave.

(h)            “ Enrollment Date ” shall mean the first Trading Day of each Offering Period.

(i)             “ Exercise Date ” shall mean the last Trading Day of each Purchase Period.

(j)             “ Fair Market Value ” shall mean, as of any date, the value of Common Stock determined as follows:

(i)              If the Common Stock is listed on any established stock exchange or a national market system, including without limitation The NASDAQ Global Market or The NASDAQ Capital Market of The NASDAQ Stock Market LLC, its Fair Market Value shall be the closing sales price for such stock (or the closing bid, if no sales were reported) as quoted on such exchange or system for the last market trading day prior to the date of determination, as reported in The Wall Street Journal or such other source as the Board deems reliable;

(ii)             If the Common Stock is regularly quoted by a recognized securities dealer but selling prices are not reported, its Fair Market Value shall be the mean of the closing bid and asked prices for the Common Stock prior to the date of determination, as reported in The Wall Street Journal or such other source as the Board deems reliable; or

(iii)           In the absence of an established market for the Common Stock, the Fair Market Value thereof shall be determined in good faith by the Board.

(k)             “ Offering Periods ” shall mean the periods of approximately twenty-four (24) months during which an option granted pursuant to the Plan may be exercised, commencing on the first Trading Day on or after May 1 and November 1 of each year and terminating on the last Trading Day in the periods ending twenty-four (24) months later; provided, however, that commencing on and after May 1, 2007, an “Offering Period” shall mean the periods of approximately twelve (12) months during with an option granted pursuant to the Plan may be exercised, commencing on the first Trading Day on or after May 1 and November 1 of each year and terminating on the last Trading Day in the periods ending twelve (12) months later. The duration and timing of Offering Periods may be changed pursuant to Section 4 of this Plan.

(l)              “ Plan ” shall mean this 1999 Employee Stock Purchase Plan.

(m)            “ Purchase Period ” shall mean the approximately six month period commencing after one Exercise Date and ending with the next Exercise Date, except that the first Purchase Period of any Offering Period shall commence on the Enrollment Date and end with the next Exercise Date.

(n)             “ Purchase Price ” shall mean 85% of the Fair Market Value of a share of Common Stock on the Enrollment Date or on the Exercise Date, whichever is lower; provided however, that the Purchase Price may be adjusted by the Board pursuant to Section 20.

(o)             “ Reserves ” shall mean the number of shares of Common Stock covered by each option under the Plan which have not yet been exercised and the number of shares of Common Stock which have been authorized for issuance under the Plan but not yet placed under option.

(p)             “ Subsidiary ” shall mean a corporation, domestic or foreign, of which not less than 50% of the voting shares are held by the Company or a Subsidiary, whether or not such corporation now exists or is hereafter organized or acquired by the Company or a Subsidiary.

(q)             “ Trading Day ” shall mean a day on which national stock exchanges and The NASDAQ Stock Exchange LLC are open for trading.

3.               Eligibility .

(a)            Any Employee who shall be employed by the Company on a given Enrollment Date shall be eligible to participate in the Plan.

(b)             Any provisions of the Plan to the contrary notwithstanding, no Employee shall be granted an option under the Plan (i) to the extent that, immediately after the grant, such Employee (or any other person whose stock would be attributed to such Employee pursuant to Section 424(d) of the Code) would own capital stock of the Company and/or hold outstanding options to purchase such stock possessing five percent (5%) or more of the total combined voting power or value of all classes of the capital stock of the Company or of any Subsidiary, or (ii) to the extent that his or her rights to purchase stock under all employee stock purchase plans of the Company and its subsidiaries accrues at a rate which exceeds Twenty-Five Thousand Dollars ($25,000) worth of stock (determined at the fair market value of the shares at the time such option is granted) for each calendar year in which such option is outstanding at any time.

4.               Offering Periods .  The Plan shall be implemented by consecutive, overlapping Offering Periods with a new Offering Period commencing on the first Trading Day on or after May 1 and November 1 each year, or on such other date as the Board shall determine, and continuing thereafter until terminated in accordance with Section 20 hereof.  The Board shall have the power to change the duration of Offering Periods (including the commencement dates thereof) with respect to future offerings without shareholder approval if such change is announced at least five (5) days prior to the scheduled beginning of the first Offering Period to be affected thereafter.

5.              Participation .

(a)             An eligible Employee may become a participant in the Plan by completing a subscription agreement authorizing payroll deductions in the form of Exhibit A to this Plan and filing it with the Company’s payroll office prior to the applicable Enrollment Date.

(b)             Payroll deductions for a participant shall commence on the first payroll following the Enrollment Date and shall end on the last payroll in the Offering Period to which such authorization is applicable, unless sooner terminated by the participant as provided in Section 10 hereof.

6.              Payroll Deductions .

(a)             At the time a participant files his or her subscription agreement, he or she shall elect to have payroll deductions made on each pay day during the Offering Period in an amount not exceeding ten (10%) of the Compensation which he or she receives on each pay day during the Offering Period.

(b)             All payroll deductions made for a participant shall be credited to his or her account under the Plan and shall be withheld in whole percentages only.  A participant may not make any additional payments into such account.

(c)             A participant may discontinue his or her participation in the Plan as provided in Section 10 hereof, or may increase or decrease the rate of his or her payroll deductions during the Offering Period by completing or filing with the Company a new subscription agreement authorizing a change in payroll deduction rate. The Board may, in its discretion, limit the number of participation rate changes during any Offering Period. The change in rate shall be effective with the first full payroll period following five (5) business days after the Company’s receipt of the new subscription agreement unless the Company elects to process a given change in participation more quickly. A participant’s subscription agreement shall remain in effect for successive Offering Periods unless terminated as provided in Section 10 hereof.

(d)             Notwithstanding the foregoing, to the extent necessary to comply with Section 423(b)(8) of the Code and Section 3(b) hereof, a participant’s payroll deductions may be decreased to zero percent (0%) at any time during a Purchase Period.  Payroll deductions shall recommence at the rate provided in such participant’s subscription agreement at the beginning of the first Purchase Period which is scheduled to end in the following calendar year, unless terminated by the participant as provided in Section 10 hereof.

(e)             At the time the option is exercised, in whole or in part, or at the time some or all of the Company’s Common Stock issued under the Plan is disposed of, the participant must make adequate provision for the Company’s federal, state, or other tax withholding obligations, if any, which arise upon the exercise of the option or the disposition of the Common Stock.  At any time, the Company may, but shall not be obligated to, withhold from the participant’s compensation the amount necessary for the Company to meet applicable withholding obligations, including any withholding required to make available to the Company any tax deductions or benefits attributable to sale or early disposition of Common Stock by the Employee.

7.               Grant of Option.   On the Enrollment Date of each Offering Period, each eligible Employee participating in such Offering Period shall be granted an option to purchase on each Exercise Date during such Offering Period (at the applicable Purchase Price) up to a number of shares of the Company’s Common Stock determined by dividing such Employee’s payroll deductions accumulated prior to such Exercise Date and retained in the Participant’s account as of the Exercise Date by the applicable Purchase Price; provided that in no event shall an Employee be permitted to purchase during each Purchase Period more than 5,000 shares of the Company’s Common Stock (subject to any adjustment pursuant to Section 19), and provided further that such purchase shall be subject to the limitations set forth in Sections 3(b) and 12 hereof.  The Board may, for future Offering Periods, increase or decrease, in its absolute discretion, the maximum number of shares of the Company’s Common Stock an Employee may purchase during each Purchase Period of such Offering Period.  Exercise of the option shall occur as provided in Section 8 hereof, unless the participant has withdrawn pursuant to Section 10 hereof.  The option shall expire on the last day of the Offering Period.

8.              Exercise of Option .

(a)             Unless a participant withdraws from the Plan as provided in Section 10 hereof, his or her option for the purchase of shares shall be exercised automatically on the Exercise Date, and the maximum number of full shares subject to option shall be purchased for such participant at the applicable Purchase Price with the accumulated payroll deductions in his or her account.  No fractional shares shall be purchased; any payroll deductions accumulated in a participant’s account which are not sufficient to purchase a full share shall be retained in the participant’s account for the subsequent Purchase Period or Offering Period, subject to earlier withdrawal by the participant as provided in Section 10 hereof. Any other monies left over in a participant’s account after the Exercise Date shall be returned to the participant.  During a participant’s lifetime, a participant’s option to purchase shares hereunder is exercisable only by him or her.

(b)             If the Board determines that, on a given Exercise Date, the number of shares with respect to which options are to be exercised may exceed (i) the number of shares of Common Stock that were available for sale under the Plan on the Enrollment Date of the applicable Offering Period, or (ii) the number of shares available for sale under the Plan on such Exercise Date, the Board may in its sole discretion (x) provide that the Company shall make a pro rata allocation of the shares of Common Stock available for purchase on such Enrollment Date or Exercise Date, as applicable, in as uniform a manner as shall be practicable and as it shall determine in its sole discretion to be equitable among all participants exercising options to purchase Common Stock on such Exercise Date, and continue all Offering Periods then in effect, or (y) provide that the Company shall make a pro rata allocation of the shares available for purchase on such Enrollment Date or Exercise Date, as applicable, i