Document:

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                                                                    Exhibit 10.4

                        AMENDMENT TO EMPLOYMENT AGREEMENT

         This Amendment to Employment Agreement (this "Amendment"), made as of
the 20th day of August, 2004, is entered into by Hybridon, Inc., a Delaware
corporation with its principal place of business at 345 Vassar Street,
Cambridge, MA 02139 (the "Company"), and Mr. Stephen R. Seiler residing at 38
Devon Road, Newton, MA 02459 ("Executive").

         WHEREAS, the Company and Executive are parties to an Employment
Agreement dated as of July 25, 2001 (the "Employment Agreement"); and

         WHEREAS, the Company and Executive desire to provide Executive with
specified rights to severance benefits if Executive or the Company give notice
of the termination of the Executive's employment during the period commencing on
the date hereof and ending on the date 90 days after the date hereof (the
"Transition Period");

         NOW THEREFORE, in consideration of these premises, the mutual covenants
and promises contained herein, and other good and valuable consideration, the
receipt and sufficiency of which are acknowledged, the parties hereto agree as
follows:

         1.       Defined Terms. The capitalized terms used herein but not
otherwise defined shall have the meanings assigned to them in the Employment
Agreement.

         2.       Voluntary Resignation. The Employment Agreement is hereby
amended by inserting the following clause immediately after clause (v) of
Section 7(a) of the Employment Agreement and renumbering clauses (vi) and (vii)
of Section 7(a) and all references to such sections of the Employment Agreement,
as amended by this Amendment, to reflect the following clause:

                  "(vi) Termination by Executive Other than for Good Reason.
                  Executive may terminate his employment under this Agreement
                  for any reason at any time upon thirty (30) days' prior
                  written notice to the Company. If Executive's employment
                  hereunder is terminated by Executive under this clause (vi),
                  the Company shall pay Executive any Accrued Obligations,
                  provided that such amount shall be paid in a lump sum cash
                  payment within thirty (30) days after such termination date.
                  Executive shall remain subject to the provisions of this
                  Agreement that, by their terms, survive the termination of
                  Executive's employment with the Company."

         3.       Severance Benefits in the Event of Voluntary Resignation. In
the event that, during the Transition Period, Executive gives notice of
termination of his employment under the Employment Agreement pursuant to Section
7(a)(vi) of the Employment Agreement, as amended by this Amendment, then,
notwithstanding the provisions of Section 7(a)(vi) to the contrary, the Company
shall provide Executive with all of the benefits to which Executive would have
been entitled under Section 7(a)(v) of the Employment Agreement if he had
terminated his employment and the Employment Agreement for Good Reason pursuant
to Section 7(a)(v) of the Employment Agreement, including but not limited to
benefits with respect to Executive's Base Salary, Accrued Obligations and stock
options.

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         4.       Cause. The Company and Executive agree that, during the
Transition Period, the term "Cause," as defined in Appendix A to the Employment
Agreement, shall have the meaning set forth below in lieu of the meaning
currently set forth on Appendix A.

                  "Cause. "Cause" shall mean Executive's (i) material breach of
                  any material term of this Agreement, (ii) plea of guilty or
                  nolo contendre to, or conviction of, the commission of a
                  felony offense or (iii) repeated unexplained or unjustified
                  absence, or refusals to carry out the lawful directions of the
                  Board, provided that any action or inaction described by (i)
                  or (iii) above shall not be the basis of a termination of
                  Executive's employment with the Company for "Cause" unless the
                  Company provided Executive with at least twenty (20) days
                  advance written notice specifying in reasonable detail the
                  conduct in need of being cured and such conduct was not cured
                  within the notice period."

         5.       Miscellaneous

         (a)      The captions of the sections of this Amendment are for
convenience of reference only and in no way define, limit, or affect the scope
or substance of any section of this Amendment.

         (b)      This Amendment shall be construed, interpreted, and enforced
in accordance with the laws of the Commonwealth of Massachusetts, without giving
effect to conflict of laws provisions.

         (c)      This Amendment, together with the Employment Agreement,
constitute the entire agreement between the parties and supersedes all prior
agreements and understandings, whether written or oral, relating to the subject
matter hereof.

         (d)      In all respects other than as specifically provided in this
Amendment, the Employment Agreement is hereby ratified and affirmed.

                                      -2-

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         In witness whereof, the parties hereto have executed this Amendment as
of the day and year set forth above.

                                       HYBRIDON, INC.

                                       By: /s/ James B. Wyngaarden
                                           -------------------------------------

                                       Title: Chairman of the Board of Directors

                                       EXECUTIVE

                                       /s/ Stephen R. Seiler
                                       -----------------------------------------
                                       Stephen R. Seiler

                                      -3-<PAGE>
                                                                     Exhibit 4.1

THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED, OR ANY STATE SECURITIES LAWS, AND MAY
NOT BE SOLD, PLEDGED, OR OTHERWISE TRANSFERRED WITHOUT AN EFFECTIVE REGISTRATION
THEREOF UNDER SUCH ACT AND LAWS OR, SUBJECT TO SECTION 5.3 HEREOF, AN OPINION OF
COUNSEL REASONABLY SATISFACTORY TO THE CORPORATION AND ITS COUNSEL, THAT SUCH
REGISTRATION IS NOT REQUIRED.

                            WARRANT TO PURCHASE STOCK

Issuer:  Evergreen Solar, Inc., a Delaware corporation
Number of Shares:  89,955, subject to adjustment
Class of Stock: Common Stock, $0.01 par value per share
Exercise Price: $3.335, subject to adjustment
Issue Date:  August 26, 2004
Expiration Date:  August 25, 2009

         FOR THE AGREED UPON VALUE of $1.00, and for other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged,
this Warrant is issued to SILICON VALLEY BANK (together with its successors and
permitted assigns, "Holder") by Evergreen Solar, Inc., a Delaware corporation
(the "Company").

         Subject to the terms and conditions hereinafter set forth, the Holder
is entitled upon surrender of this Warrant and the duly executed Notice of
Exercise form annexed hereto as Appendix 1 ("Notice of Exercise"), at the
principal office of the Company, 138 Bartlett Street, Marlboro, Massachusetts
01752 or such other office as the Company shall notify the Holder of in writing,
to purchase from the Company up to Eighty-nine Thousand Nine Hundred Fifty-five
fully paid and non-assessable shares (the "Shares") of the Company's common
stock, $0.01 par value per share ("Common Stock") at a purchase price per Share
of $3.335 (the "Exercise Price"). This Warrant may be exercised in whole or in
part at any time and from time to time until 5:00 PM, Eastern time, on the
Expiration Date, and shall be void thereafter. Until such time as this Warrant
is exercised in full or expires, the Exercise Price and the Shares are subject
to adjustment from time to time as hereinafter provided.

ARTICLE 1. EXERCISE.

         1.1      Method of Exercise. Holder may exercise this Warrant by
delivering a duly executed Notice of Exercise to the principal office of the
Company. Unless Holder is exercising the conversion right set forth in Section
1.2, Holder shall also deliver to the Company a check for the aggregate Exercise
Price for the Shares being purchased.

         1.2      Conversion Right. In lieu of exercising this Warrant as
specified in Section 1.1, Holder may from time to time convert this Warrant, in
whole or in part, into a number of Shares determined as follows:
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                     X = Y (A-B)/A

         where:
                     X = the number of Shares to be issued to the Holder.

                     Y = the number of Shares with respect to
                         which this Warrant is being exercised.

                     A = the Fair Market Value (as determined
                         pursuant to Section 1.3 below) of one Share.

                     B = the Exercise Price.

         1.3      Fair Market Value.

                  1.3.1    If shares of Common Stock are traded on a nationally
         recognized securities exchange, inter-dealer quotation system or over
         the counter market, the fair market value of one Share shall be the
         closing price of a share of Common Stock reported for the business day
         immediately preceding the date of Holder's Notice of Exercise to the
         Company.

                  1.3.2    If shares of Common Stock are not traded on a
         nationally recognized securities exchange or over the counter market,
         the Board of Directors of the Company shall determine the fair market
         value of a share of Common Stock in its reasonable good faith judgment.

         1.4      Delivery of Certificate and New Warrant. Promptly after Holder
exercises or converts this Warrant, the Company shall deliver to Holder
certificates for the Shares acquired and, if this Warrant has not been fully
exercised or converted and has not expired, a new Warrant representing the right
to purchase the Shares not so acquired.

         1.5      Replacement of Warrants. On receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and, in the case of loss, theft or destruction, on delivery of an
indemnity agreement reasonably satisfactory in form and amount to the Company
or, in the case of mutilation, on surrender and cancellation of this Warrant,
the Company at its expense shall execute and deliver, in lieu of this Warrant, a
new warrant of like tenor.

         1.6      Assumption on Sale, Merger, or Consolidation of the Company.

                  1.6.1    "Acquisition". For the purpose of this Warrant,
         "Acquisition" means any sale, transfer, exclusive license, or other
         disposition of all or substantially all of the assets of the Company,
         or any acquisition, reorganization, consolidation or merger of the
         Company where the holders of the Company's outstanding voting equity
         securities immediately prior to the transaction beneficially own less
         than a majority of the

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         outstanding voting equity securities of the surviving or successor
         entity immediately following the transaction.

                  1.6.2    Upon the closing of any Acquisition (other than an
         Acquisition in which the consideration received by the Company's
         stockholders consists solely of cash and/or cash equivalents), and as a
         condition precedent thereto, the successor or surviving entity shall
         assume the obligations of this Warrant, and this Warrant shall be
         exercisable for the same securities and property as would be payable
         for the Shares issuable upon exercise of the unexercised portion of
         this Warrant as if such Shares were outstanding on the record date for
         the Acquisition and subsequent closing. The Exercise Price shall be
         adjusted accordingly, and the Exercise Price and number and class of
         Shares shall continue to be subject to adjustment from time to time in
         accordance with the provisions hereof. Upon the closing of any
         Acquisition in which the consideration received by the Company's
         stockholders consists solely of cash and/or cash equivalents, then, to
         the extent not exercised or converted on or before the closing of such
         Acquisition, this Warrant shall terminate and be of no further force or
         effect.

ARTICLE 2. ADJUSTMENTS TO THE SHARES.

         2.1      Stock Dividends, Splits, Etc. If the Company declares or pays
a dividend on the outstanding shares of Common Stock, payable in Common Stock or
other securities, or subdivides the outstanding Common Stock into a greater
amount of Common Stock, then upon exercise of this Warrant, for each Share
acquired, Holder shall receive, without cost to Holder, the total number and
kind of securities to which Holder would have been entitled had Holder owned the
Shares of record as of the date the dividend or subdivision occurred.

         2.2      Reclassification, Exchange or Substitution. Upon any
reclassification, exchange, substitution, or other event that results in a
change of the number and/or class of the securities issuable upon exercise or
conversion of this Warrant, Holder shall be entitled to receive, upon exercise
or conversion of this Warrant, the number and kind of securities and property
that Holder would have received for the Shares if this Warrant had been
exercised immediately before such reclassification, exchange, substitution, or
other event. The Company or its successor shall promptly issue to Holder a new
Warrant for such new securities or other property. The new Warrant shall provide
for adjustments which shall be as nearly equivalent as may be practicable to the
adjustments provided for in this Article 2 including, without limitation,
adjustments to the Exercise Price and to the number of securities or property
issuable upon exercise of the new Warrant. The provisions of this Section 2.2
shall similarly apply to successive reclassifications, exchanges, substitutions,
or other events.

         2.3      Adjustments for Combinations, Etc. If the outstanding shares
of Common Stock are combined or consolidated, by reclassification or otherwise,
into a lesser number of shares, the Exercise Price shall be proportionately
increased and the number of Shares shall be proportionately decreased.

         2.4      No Impairment. The Company shall not, by amendment of its
Certificate of Incorporation or by-laws, or through a reorganization, transfer
of assets, consolidation, merger, dissolution, issue, or sale of securities or
any other voluntary action, avoid or seek to avoid the

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observance or performance of any of the terms to be observed or performed under
this Warrant by the Company, but shall at all times in good faith assist in
carrying out of all the provisions of this Article 2 and in taking all such
action as may be necessary or appropriate to protect Holder's rights under this
Article against impairment.

         2.5      Adjustments for Certain Diluting Issuances. In the event that
at any time and from time to time, the Company sells or issues shares of its
Common Stock, or securities or instruments convertible into, exercisable for, or
otherwise representing the right to purchase or acquire, shares of Common Stock,
to one or more providers of debt, equity, lease or equipment financing to the
Company or any of its affiliates, in a private transaction not registered under
the Securities Act of 1933, as amended, at an effective Common Stock conversion,
exercise or purchase price that is less than both (i) the then-effective
Exercise Price, and (ii) the average closing price of a share of Common Stock
over the five (5) trading days immediately preceding the date of issuance as
reported on the national securities exchange, inter-dealer quotation system or
over-the-counter market on which the Company's Common Stock is then listed or
quoted, then, automatically upon and concurrently with such sale or issuance by
the Company, the Exercise Price shall be lowered to such effective conversion,
exercise or purchase price.

         2.6      Fractional Shares. No fractional Shares shall be issuable upon
exercise or conversion of the Warrant and the number of Shares to be issued
shall be rounded down to the nearest whole Share. If a fractional Share interest
arises upon any exercise or conversion of this Warrant, the Company shall
eliminate such fractional Share interest by paying Holder an amount computed by
multiplying such fractional interest by the Fair Market Value (determined in
accordance with Section 1.3 above) of one Share.

         2.7      Certificate as to Adjustments. Upon each adjustment of the
Exercise Price, number of Shares or class of security for which this Warrant is
exercisable, the Company at its expense shall promptly compute such adjustment,
and furnish Holder with a certificate of its chief financial officer setting
forth such adjustment and the facts upon which such adjustment is based. The
Company shall, upon written request, furnish Holder a certificate setting forth
the Exercise Price, number of Shares and class of security for which this
Warrant is exercisable in effect upon the date thereof and the series of
adjustments leading to such Exercise Price, number of Shares and class of
security.

ARTICLE 3. REPRESENTATIONS AND COVENANTS OF THE COMPANY.

         3.1      Representations and Warranties. The Company hereby represents
and warrants to the Holder as follows:

                  3.1.1    All Shares which may be issued upon the due exercise
         of this Warrant shall, upon issuance, be duly authorized, validly
         issued, fully paid and non-assessable, and free of any liens and
         encumbrances except for restrictions on transfer provided for herein or
         under applicable federal and state securities laws.

                  3.1.2    The Company covenants that it shall at all times
         cause to be reserved and kept available out of its authorized and
         unissued shares such number of shares of its Common Stock and other
         securities as will be sufficient to permit the exercise in full of

<PAGE>

         this Warrant and the conversion or exchange of such Common Stock into
         or for such other securities.

                  3.1.3    The execution and delivery by the Company of this
         Warrant and the performance of all obligations of the Company
         hereunder, including the issuance to Holder of the Shares upon exercise
         or conversion hereof, (i) have been duly authorized by all necessary
         corporate action on the part of the Company, its Board of Directors and
         stockholders, (ii) do not conflict with or violate the Certificate
         and/or the Company's by-laws, (iii) do not contravene any law or
         governmental rule, regulation or order applicable to it, and (iv) do
         not contravene any provision of, or constitute a default under, any
         material indenture, mortgage, contract or other instrument to which it
         is a party or by which it is bound. This Warrant constitutes the legal,
         valid and binding agreement of the Company, enforceable in accordance
         with its terms.

         3.2      Intentionally Omitted.

         3.3      Registration Under Securities Act of 1933, as amended. The
Shares issued and issuable hereunder shall have certain incidental or
"piggyback" registration rights pursuant to, and as set forth in, that certain
Registration Rights Agreement of even date herewith between Holder and the
Company; provided, that such Agreement shall provide that Holder may include
Shares in any registration only after all other holders, as of the Issue Date
hereof, of registration rights as to Company securities held by such holders
shall have included all shares requested by such holders to be included in such
registration. The Company represents and warrants to Holder that the Company's
foregoing grant of registration rights and its execution, delivery and
performance of the aforementioned Registration Rights Agreement (a) have been
duly authorized by all necessary corporate action of the Company's Board of
Directors and shareholders, (b) will not violate the Certificate or the
Company's by-laws, each as amended, (c) will not violate or cause a breach or
default (or an event which with the passage of time or the giving of notice or
both, would constitute a breach or default) under any agreement, instrument,
mortgage, deed of trust or other arrangement to which the Company is a party or
by which it or any of its assets is subject or bound, and (d) do not require the
approval, consent or waiver of or by any shareholder, registration rights holder
or other third party which approval, consent or waiver has not been obtained as
of the date of issuance of this Warrant.

ARTICLE 4. REPRESENTATIONS AND WARRANTIES OF THE HOLDER.

         4.1      Purchase for Own Account. This Warrant and the Shares to be
acquired upon exercise hereof will be acquired for investment for Holder's
account, not as nominee or agent, and not with a view to sale or distribution in
violation of applicable federal and state securities laws; provided that, for
regulatory reasons, Silicon Valley Bank will transfer this Warrant to its parent
corporation, Silicon Valley Bancshares, promptly following issuance hereof.

         4.2      Investment Experience. Holder understands that the purchase of
this Warrant and the Shares covered hereby involves substantial risk. Holder (a)
has experience as an investor in unregistered securities, (b) has sufficient
knowledge and experience in financial and business affairs that it evaluate the
risks and merits of its investment in this Warrant and the Shares, and (c) can
bear the economic risk of such Holder's investment in this Warrant and the
Shares.

<PAGE>

         4.3      Accredited Investor. Holder is an "accredited investor" as
such term is defined in Regulation D under the Securities Act of 1933, as
amended.

ARTICLE 5. MISCELLANEOUS.

         5.1      Intentionally Omitted.

         5.2      Legends. This Warrant and the Shares shall be imprinted with a
legend in substantially the following form:

                  THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT
                  OF 1933, AS AMENDED, OR ANY STATE SECURITIES LAWS, AND MAY NOT
                  BE SOLD, PLEDGED OR OTHERWISE TRANSFERRED WITHOUT AN EFFECTIVE
                  REGISTRATION THEREOF UNDER SUCH ACT AND LAWS OR, SUBJECT TO
                  SECTION 5.3 OF THAT CERTAIN WARRANT TO PURCHASE STOCK ISSUED
                  BY THE CORPORATION TO SILICON VALLEY BANK DATED AS OF
                  _______________, AN OPINION OF COUNSEL REASONABLY SATISFACTORY
                  TO THE CORPORATION AND ITS COUNSEL THAT SUCH REGISTRATION IS
                  NOT REQUIRED.

         5.3      Compliance with Securities Laws on Transfer. This Warrant and
the Shares may not be transferred or assigned in whole or in part without
compliance with applicable federal and state securities laws by the transferor
and the transferee (including, without limitation, the delivery of investment
representation letters and legal opinions reasonably satisfactory to the
Company, as reasonably requested by the Company). The Company shall not require
Holder to provide an opinion of counsel if the transfer is to Silicon Valley
Bancshares or other affiliate of Holder.

         5.4      Transfer Procedure. Following its receipt of this executed
Warrant, Silicon Valley Bank will transfer same in whole or in part to its
parent corporation Silicon Valley Bancshares, and thereafter Holder and/or
Silicon Valley Bancshares may, subject to Section 5.3 above, transfer all or
part of this Warrant and/or the Shares at any time and from time to time by
giving the Company notice of the portion of the Warrant and/or Shares being
transferred setting forth the name, address and taxpayer identification number
of the transferee and surrendering this Warrant to the Company for reissuance to
the transferee(s) (and Holder if applicable).

         5.5      Notices. All notices and other communications from the Company
to the Holder, or vice versa, shall be deemed delivered and effective when given
personally, or mailed by first-class registered or certified mail, postage
prepaid, or sent via reputable overnight courier service, fee prepaid, at such
address as may have been furnished to the Company or the Holder, as the case may
be, in writing by the Company or such holder from time to time, but in all
cases, unless instructed in writing otherwise, the Company shall deliver a copy
of all notices to Holder to Silicon Valley Bank, Treasury Department, 3003
Tasman Drive, HA-200, Santa Clara, California 95054.
<PAGE>

         5.6      Waiver. This Warrant and any term hereof may be changed,
waived, discharged or terminated only by an instrument in writing signed by the
party against which enforcement of such change, waiver, discharge or termination
is sought.

         5.7      Attorneys Fees. In the event of any dispute between the
parties concerning the terms and provisions of this Warrant, the party
prevailing in such dispute shall be entitled to collect from the other party all
costs incurred in such dispute, including reasonable attorneys' fees.

         5.8      Governing Law. This Warrant shall be governed by and construed
in accordance with the laws of The Commonwealth of Massachusetts, without giving
effect to its principles regarding conflicts of law.

         5.9      No Rights as a Shareholder. Except as specifically provided in
this Warrant, Holder shall have no rights as a shareholder of the Company in
respect of the Shares issuable hereunder unless and until Holder exercises this
Warrant as to all or any of such Shares.

                  [REMAINDER OF PAGE LEFT BLANK INTENTIONALLY]

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         IN WITNESS WHEREOF, the Company has caused this Warrant to Purchase
Stock to be executed as an instrument under seal by its duly authorized
representative as of the date first above written.

ATTEST:                        "COMPANY"

                                EVERGREEN SOLAR, INC.

By:   /s/ Mark Fidler           By:    /s/ Richard G. Chleboski
    ---------------------            ---------------------------------------

Name:   Mark Fidler             Name:  Richard G. Chleboski
Title:  Controller              Title: Chief Financial Officer/Vice President

<PAGE>
                                   APPENDIX 1

                               NOTICE OF EXERCISE

         1.       The undersigned hereby elects to purchase _______shares of the
____________ stock of __________________ pursuant to Section 1.1 of the attached
Warrant, and tenders herewith payment of the Exercise Price of such shares in
full.

         1.       The undersigned hereby elects to convert the attached Warrant
into Shares in the manner specified in Section 1.2 of the attached Warrant. This
conversion is exercised with respect to ____________ of shares of the
________________________ Stock of ___________________.

          [Strike paragraph that does not apply.]

         2.       Please issue a certificate or certificates representing said
shares in the name of the undersigned or in such other name as is specified
below:

                                     -------------------------------------
                                     (Name)

                                     -------------------------------------
                                     (Address)

         3.       The undersigned represents it is acquiring the shares solely
for its own account and not as a nominee for any other party and not with a view
toward the resale or distribution thereof except in compliance with applicable
securities laws.

                                     -------------------------------------
                                     (Signature)

--------------------
         (Date)

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