<Page>
SCHEDULE 14C INFORMATION

Information Statement Pursuant to Section 14(c) of
the Securities Exchange Act of 1934

<Table>

Check the appropriate box:
/ / Preliminary Information Statement
/ / Confidential, for Use of the Commission Only (as permitted
by Rule 14c-5(d)(2))
/X/ Definitive Information Statement
</Table>

_____________________________ILLINOIS POWER COMPANY_____________________________
(Name of Registrant As Specified In Its Charter)

Payment of Filing Fee (Check the appropriate box):

<Table>

/X/ No fee required
/ / Fee computed on table below per Exchange Act Rules 14c-5(g) and
0-11
(1) Title of each class of securities to which transaction
applies:
----------------------------------------------------------
(2) Aggregate number of securities to which transaction
applies:
----------------------------------------------------------
(3) Per unit price or other underlying value of transaction
computed pursuant to Exchange Act Rule 0-11 (set forth the
amount on which the filing fee is calculated and state how
it was determined):
----------------------------------------------------------
(4) Proposed maximum aggregate value of transaction:
----------------------------------------------------------
(5) Total fee paid:
----------------------------------------------------------

/ / Fee paid previously with preliminary materials.

/ / Check box if any part of the fee is offset as provided by
Exchange Act Rule 0-11(a)(2) and identify the filing for which
the offsetting fee was paid previously. Identify the previous
filing by registration statement number, or the Form or
Schedule and the date of its filing.

(1) Amount Previously Paid:
----------------------------------------------------------
(2) Form, Schedule or Registration Statement No.:
----------------------------------------------------------
(3) Filing Party:
----------------------------------------------------------
(4) Date Filed:
----------------------------------------------------------
</Table>
<Page>
NOTICE OF ANNUAL MEETING OF SHAREHOLDERS
TO BE HELD MONDAY, NOVEMBER 19, 2001

To the Shareholders of Illinois Power Company:

NOTICE IS HEREBY GIVEN, that the Annual Meeting of Shareholders of Illinois
Power Company, an Illinois corporation ("Illinois Power"), will be held on
Monday, November 19, 2001 at 10:00 a.m., local time, at the Dynegy Inc.
Headquarters, The Wells Fargo Bank Building, 1000 Louisiana, 71st Floor,
Houston, Texas 77002, for the following purposes:

(1) To elect the Board of Directors to serve until the 2002 Annual Meeting
of Shareholders.

(2) To ratify the appointment of Arthur Andersen LLP as the independent
auditors of Illinois Power for the 2001 fiscal year.

(3) To transact any other business which may properly come before the
meeting or any adjournment(s) or postponement(s) thereof.

Shareholders of record at the close of business on October 19, 2001 will be
entitled to receive notice of and to vote at the Annual Meeting or any
adjournment(s) or postponement(s) thereof.

By Order of the Board of Directors,

/s/ Kathryn L. Patton

Kathryn L. Patton
SENIOR VICE PRESIDENT, GENERAL COUNSEL
AND SECRETARY

Decatur, Illinois
October 29, 2001

IMPORTANT

Only shareholders of Illinois Power as of the record date set forth above
are entitled to attend the Annual Meeting. Shareholders will be admitted on
verification of record stock ownership at the admission desk. Shareholders who
own stock through banks, brokerage firms, nominees or other account custodians
must present proof of beneficial stock ownership (such as a brokerage account
statement) at the admission desk.
<Page>
ILLINOIS POWER COMPANY
500 SOUTH 27TH STREET
DECATUR, ILLINOIS 62525
(217) 424-6600

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

INFORMATION STATEMENT

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

October 29, 2001
(Date first sent or given to security holders)

WE ARE NOT ASKING YOU FOR A PROXY AND YOU ARE REQUESTED NOT TO SEND US A PROXY.

This Information Statement is furnished in connection with the Annual
Meeting of Shareholders of Illinois Power Company ("Illinois Power") to be held
on Monday, November 19, 2001 at 10:00 a.m., local time, at the Dynegy Inc.
Headquarters, The Wells Fargo Bank Building, 1000 Louisiana, 71st Floor,
Houston, Texas 77002, for the purposes set forth in the accompanying Notice of
Annual Meeting of Shareholders.

Illinois Power has publicly traded preferred stock outstanding and common
stock wholly owned by Illinova Corporation ("Illinova"). On February 1, 2000,
Illinova and its subsidiaries, including Illinois Power, were acquired by
Dynegy Inc. ("Dynegy"). The merger involved the creation of a new holding
company, now known as Dynegy Inc., and two separate but concurrent mergers. As a
result of these two mergers, in which wholly owned subsidiaries of Dynegy Inc.
merged with and into the former Dynegy and Illinova, respectively, Illinova and
the former Dynegy continue to exist as wholly owned subsidiaries of Dynegy Inc.
At their election, previous Dynegy shareholders received, in exchange for each
share of Dynegy common stock, either 0.69 shares of new Dynegy Class A common
stock or $16.50 in cash consideration per share, and previous Illinova
shareholders exchanged their shares for new Dynegy Class A common stock on a
share-for-share basis.

On October 19, 2001 (the "Record Date"), Dynegy beneficially owned all of
the 62,892,213 shares of Illinois Power common stock then outstanding and there
were 912,675 shares of Illinois Power preferred stock then outstanding, none of
which was beneficially held by Dynegy.

VOTING RIGHTS

Shareholders of record at the close of business on the Record Date will be
entitled to receive notice of and to vote at the Annual Meeting. Shareholders
who are present at the Annual Meeting will be entitled to one vote for each
share of Illinois Power stock that they held of record at the close of business
on the Record Date.

When voting for candidates nominated to serve as directors, all shareholders
will be entitled to five votes (the number of directors to be elected) for each
of their shares and may cast all of their votes for any one candidate whose name
has been placed in nomination prior to the voting, or distribute their votes
among two or more such candidates in such proportions as they determine. In
voting on other matters presented for consideration at the Annual Meeting, each
shareholder will be entitled to one vote for each share of stock held of record
at the close of business on the Record Date.

ANNUAL REPORT AND INFORMATION STATEMENT

Accompanying this Information Statement is a Notice of Annual Meeting of
Shareholders and the Annual Report on Form 10-K for Illinois Power for the year
ended December 31, 2000. This Information Statement and accompanying documents
are first being mailed on or about October 29, 2001 to shareholders of record at
the close of business on the Record Date.

1
<Page>
BOARD OF DIRECTORS

INFORMATION REGARDING THE BOARD OF DIRECTORS

During 2000, the Illinois Power Board of Directors held no meetings but did
take action nine times by unanimous written consent. The Board does not have any
standing committees.

BOARD COMPENSATION

None of Illinois Power's directors receive special or additional
compensation as a result of their service on the Board of Directors.

ELECTION OF DIRECTORS

Illinois Power's entire Board of Directors is elected at each Annual Meeting
of Shareholders. The directors serve in such capacity until Illinois Power's
next annual shareholder meeting and until their respective successors have been
duly elected and qualified, or until their earlier death, resignation or
removal. At the Annual Meeting a vote will be taken on a proposal to elect the
five directors nominated by Illinois Power's Board of Directors. The names and
certain additional information concerning each of the director nominees,
including their ages as of September 30, 2001, is set forth on the following
pages. If any nominee should become unable to serve as a director, another
nominee may be selected by the current Board of Directors.

<Table>
<Caption>
NAME OF DIRECTOR NOMINEE, AGE, YEAR IN WHICH FIRST
BUSINESS EXPERIENCE ELECTED A DIRECTOR
AND OTHER INFORMATION OF ILLINOIS POWER
--------------------- -----------------

C.L. WATSON, 51 2000
</Table>

C.L. Watson has served as Chairman of the Board of Directors of Illinois Power
since February 2000, following the consummation of the Dynegy-Illinova merger.
Mr. Watson also serves as Chairman and Chief Executive Officer of Dynegy. He
founded Natural Gas Clearinghouse ("Clearinghouse"), a predecessor of Dynegy, in
1985 and served as President and Chief Executive Officer of Clearinghouse from
1985 to 1995. He served as a member of the Management Committee of Clearinghouse
from 1985 to 1995 and was elected Chairman of the Management Committee of
Clearinghouse in 1989. Mr. Watson also serves on the Board of Directors of Baker
Hughes Incorporated.

<Table>

STEPHEN W. BERGSTROM, 44 2000
</Table>

Stephen W. Bergstrom has served as Chief Executive Officer and a director of
Illinois Power since February 2000, following the consummation of the
Dynegy-Illinova merger. Mr. Bergstrom has also served as President and Chief
Operating Officer of Dynegy since August 1999. He has also served as a member of
Dynegy's Board of Directors and as President of Dynegy Marketing and Trade
(f/k/a Clearinghouse) since 1995. He served as Executive Vice President of
Clearinghouse and a member of the Clearinghouse Management Committee from 1989
through 1995.

<Table>

LARRY F. ALTENBAUMER, 53 2000
</Table>

Larry F. Altenbaumer has served as President of Illinois Power since
September 1999. Mr. Altenbaumer also has served as a director of Illinois Power
and as Senior Vice President of Dynegy since February 2000, following the
consummation of the Dynegy-Illinova merger. Mr. Altenbaumer previously served as
Senior Vice President and Chief Financial Officer of Illinois Power from 1992
until September 1999 and as Senior Vice President, Chief Financial Officer,
Treasurer and Controller of Illinova from June 1994 until September 1999.

2
<Page>

<Table>

ROBERT D. DOTY, 44 2000
</Table>

Robert D. Doty has served as Executive Vice President of Illinois Power since
July 2001 and as Chief Financial Officer and a director of Illinois Power since
May 2000. Mr. Doty also serves as Executive Vice President and Chief Financial
Officer of Dynegy and has served as Dynegy's principal financial officer since
May 2000. In such capacity, he is responsible for the overall financial strategy
and operation of Dynegy. He is responsible for accounting, finance, investor
relations, risk control, treasury and tax. Mr. Doty joined Dynegy in 1991 and,
prior to May 2000, served Dynegy in various capacities, including as Senior Vice
President, Finance. Prior to joining Dynegy, Mr. Doty was employed by Arthur
Andersen LLP.

<Table>

KENNETH E. RANDOLPH, 45 2000
</Table>

Kenneth E. Randolph has served as a director of Illinois Power since
February 2000, following the consummation of the Dynegy-Illinova merger.
Mr. Randolph also serves as Executive Vice President and General Counsel of
Dynegy. He has served as Executive Vice President of Dynegy since July 2001 and
as General Counsel of Dynegy and its predecessor, Clearinghouse, since
July 1987. In addition, he served as a member of the Clearinghouse Management
Committee from May 1989 through February 1994 and managed its marketing
operations in the Western and Northwestern United States from July 1984 through
July 1987. Prior to his employment with Clearinghouse, Mr. Randolph was
associated with the Washington, D.C. office of Akin, Gump, Strauss, Hauer &
Feld, L.L.P.

3
<Page>
EXECUTIVE OFFICERS

<Table>
<Caption>
SERVED WITH THE
NAME AGE* POSITION(S) COMPANY SINCE
---- -------- ----------------------------------- ---------------

Stephen W. Bergstrom............... 44 Chief Executive Officer 2000
Larry F. Altenbaumer............... 53 President 1970
David W. Butts..................... 46 Executive Vice President 1978
Robert D. Doty..................... 44 Chief Financial Officer and 2000
Executive Vice President
Kathryn L. Patton.................. 37 Senior Vice President, General 2000
Counsel and Secretary
Peggy E. Carter.................... 38 Vice President and Controller 1985
</Table>

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

* As of September 30, 2001.

MR. BERGSTROM'S information is set forth above.

MR. ALTENBAUMER'S information is set forth above.

DAVID W. BUTTS has served as Executive Vice President of Illinois Power since
September 1999. Mr. Butts also serves as Senior Vice President of Dynegy.
Mr. Butts previously served as Chief Operating Officer of Illinois Power from
September 1999 until June 2001 and as President of Illinova Energy Partners, an
affiliate of Illinois Power, from February 1998 until September 1999. Prior to
being elected President of Illinova Energy Partners, Mr. Butts was Senior Vice
President of Illinois Power and, from November 1993 through August 1995, he was
President of Illinova Generating Company, another Illinois Power affiliate.

MR. DOTY'S information is set forth above.

KATHRYN L. PATTON has served as General Counsel and Secretary of Illinois Power
since February 2000 and was elected to serve in such capacities following the
consummation of the Dynegy-Illinova merger. Ms. Patton also has served as Senior
Vice President of Illinois Power and Vice President and Assistant General
Counsel of Dynegy since July 2001, prior to which she served as Vice President
of Illinois Power from February 2001 to July 2001. Ms. Patton previously served
Dynegy as Director and Regulatory Counsel from May 1995 to March 1999 and Senior
Director and Regulatory Counsel from March 1999 until February 2000.

PEGGY E. CARTER has served as Vice President of Illinois Power since
February 2000 and as Controller since November 1999. Ms. Carter was elected to
serve as Vice President of Illinois Power following the consummation of the
Dynegy-Illinova merger. Ms. Carter previously served Illinois Power in various
capacities from 1985, including Business Leader in Illinois Power's accounting
department from August 1994 until November 1999.

SECURITY OWNERSHIP OF MANAGEMENT AND CERTAIN BENEFICIAL OWNERS

All of Illinois Power's common stock is owned by Illinova, which is a wholly
owned subsidiary of Dynegy. Illinois Power also has six series of preferred
stock outstanding, none of which is owned by any director or executive officer.
Moreover, to the best of Illinois Power's knowledge, no owner holds more than 5%
of any such series of preferred stock. Of the 63,804,888 shares of Illinois
Power stock eligible to vote at the Annual Meeting, 62,892,213 shares, or 98.6%,
are beneficially held by Dynegy.

4
<Page>
The following table sets forth, as of September 30, 2001 except as otherwise
noted, certain information regarding beneficial ownership of the capital stock
of Dynegy by:

- each person who is known by Illinois Power to own beneficially more than
5% of Dynegy's capital stock,

- each director of Illinois Power,

- Illinois Power's Chief Executive Officer and its four other most highly
compensated executive officers, and

- all directors and executive officers of Illinois Power as a group.

Share amounts and percentages shown for each individual or group in the
table have been adjusted to give effect to (i) the two-for-one stock split
effected by Dynegy in August 2000, (ii) the exercise of all options, warrants
and convertible securities exercisable by each individual within 60 days of
September 30, 2001 and (iii) the .69 merger conversion ratio used in the
Dynegy-Illinova merger.

<Table>
<Caption>
NUMBER OF SHARES(1)
---------------------------
CLASS A CLASS B PERCENT OF CLASS A
COMMON STOCK COMMON STOCK COMMON STOCK(2)
------------ ------------ ------------------

Chevron Corporation(3) ........................... -- 86,499,914 26.6(3)
Chevron USA Inc.
575 Market Street
San Francisco, CA 94104
AXA Financial, Inc.(4) ........................... 28,958,896 -- 12.1
1290 Avenue of the Americas
New York, NY 10104
Fidelity Management & Research Company(5) ........ 16,703,190 -- 7.0
82 Devonshire
Boston, MA 02109
Larry F. Altenbaumer(6)........................... 89,526 -- *
Stephen W. Bergstrom(7)........................... 3,337,084 -- 1.4
David W. Butts(8)................................. 59,264 -- *
Peggy E. Carter(9)................................ 1,950 -- *
Robert D. Doty(10)................................ 322,163 -- *
Kathryn L. Patton(11)............................. 27,845 -- *
Kenneth E. Randolph(12)........................... 1,854,717 -- *
C.L. Watson(13)................................... 12,349,804 -- 5.2
Executive Officers and Directors of Illinois Power
as a Group
(8 Persons)(6)(7)(8)(9)(10)(11)(12)(13)......... 18,042,353 -- 7.5
</Table>

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

* Less than 1%.

(1) Unless otherwise noted, each of the persons has sole voting and investment
power with respect to the shares reported.

(2) Based upon 239,185,623 shares of Class A common stock and 86,499,914 shares
of Class B common stock outstanding.

(3) The shares are held of record by Chevron USA Inc. ("Chevron USA"). Chevron
Corporation beneficially owns 100% of the capital stock of Chevron USA.
Consequently, Chevron Corporation may be deemed to beneficially own all of
the shares of Class B common stock owned of record by Chevron USA. Percent
of Class A common stock beneficially owned assumes conversion of Class B
common stock for purposes of computing Chevron's beneficial ownership only.

5
<Page>
(4) According to its Form 13G filed with the SEC on August 10, 2001. Advisor
subsidiaries of AXA Financial, Inc. have sole voting power for
12,009,976 shares and sole power to dispose or direct the disposition of
28,956,816 shares.

(5) According to its Form 13G/A for the year ended December 31, 2000. Advisor
subsidiaries of Fidelity Management & Research Company have sole voting
power for 3,948,602 shares and sole power to dispose or direct the
disposition of 16,703,190 shares.

(6) Includes 76,206 shares of Class A common stock issuable upon the exercise of
employee stock options held by Mr. Altenbaumer. Also includes approximately
6,546 shares of Class A common stock held by the Trustee of Illinois Power's
401(k) Plan (the "Illinois Power 401(k) Plan") as of September 30, 2001 for
the account of Mr. Altenbaumer. Mr. Altenbaumer holds voting power with
respect to such shares.

(7) Includes 601,174 shares of Class A common stock that are owned by trusts
established by Mr. Bergstrom for the benefit of his minor children.
Mr. Bergstrom's father is the sole trustee of such trusts. Mr. Bergstrom
disclaims beneficial ownership of all of the shares of Class A common stock
held by such trusts. Also includes 824,691 shares of Class A common stock
issuable upon the exercise of employee stock options held by Mr. Bergstrom.
The number of shares does not include approximately 6,222 shares of Class A
common stock held by the Trustee of the Dynegy Inc. Profit Sharing/401(k)
Savings Plan (the "Dynegy 401(k) Plan") as of September 30, 2001 for the
account of Mr. Bergstrom. Participants in the Dynegy 401(k) Plan have no
voting or investment power with respect to such shares until their
distribution to such participants upon termination of their employment. In
addition, Mr. Bergstrom may elect to take cash in lieu of shares of Class A
common stock held in his Dynegy 401(k) Plan account upon termination of his
employment.

(8) Includes 262 shares of Class A common stock that are owned by trusts
established by Mr. Butts for the benefit of his minor children. Mr. Butts'
wife is the sole trustee of such trusts. Mr. Butts disclaims beneficial
ownership of all of the shares of Class A common stock held by such trusts.
Also includes 53,976 shares of Class A common stock issuable upon the
exercise of employee stock options held by Mr. Butts. Also includes
approximately 2,284 shares of Class A common stock held by the Trustee of
the Illinois Power 401(k) Plan as of September 30, 2001 for the account of
Mr. Butts. Mr. Butts holds voting power with respect to such shares.

(9) All of such shares are held by the Trustee of the Illinois Power 401(k) Plan
as of September 30, 2001 for the account of Ms. Carter. Ms. Carter holds
voting power with respect to such shares.

(10) Includes 293,448 shares of Class A common stock issuable upon the exercise
of employee stock options held by Mr. Doty. The number of shares does not
include approximately 5,900 shares of Class A common stock held by the
Trustee of the Dynegy 401(k) Plan as of September 30, 2001 for the account
of Mr. Doty. Participants in the Dynegy 401(k) Plan have no voting or
investment power with respect to such shares until their distribution to
such participants upon termination of their employment. In addition,
Mr. Doty may elect to take cash in lieu of shares of Class A common stock
held in his Dynegy 401(k) Plan account upon termination of his employment.

(11) Includes 27,415 shares of Class A common stock issuable upon the exercise
of employee stock options held by Ms. Patton. The number of shares does not
include approximately 4,219 shares of Class A common stock held by the
Trustee of the Dynegy 401(k) Plan as of September 30, 2001 for the account
of Ms. Patton. Participants in the Dynegy 401(k) Plan have no voting or
investment power with respect to such shares until their distribution to
such participants upon termination of their employment. In addition,
Ms. Patton may elect to take cash in lieu of shares of Class A common stock
held in her Dynegy 401(k) Plan account upon termination of her employment.

(12) Includes 257,745 shares of Class A common stock issuable upon the exercise
of employee stock options held by Mr. Randolph. The number of shares does
not include approximately 6,125 shares

6
<Page>
of Class A common stock held by the Trustee of the Dynegy 401(k) Plan as of
September 30, 2001 for the account of Mr. Randolph. Participants in the
Dynegy 401(k) Plan have no voting or investment power with respect to such
shares until their distribution to such participants upon termination of
their employment. In addition, Mr. Randolph may elect to take cash in lieu
of shares of Class A common stock held in his Dynegy 401(k) Plan account
upon termination of his employment.

(13) Includes 8,524,816 shares held of record by two limited partnerships, of
which (i) Mr. Watson and his wife are the sole shareholders of the corporate
general partner, and (ii) Mr. Watson (individually), his wife and certain
trusts (the "Trusts") established by Mr. Watson for the benefit of his three
children, of which Mr. Watson or his wife are the sole trustees, and a
corporation, of which Mr. Watson and the Trusts are the sole shareholders,
are the sole limited partners (the "Family Limited Partnerships").
Mr. Watson may be deemed to beneficially own all of the shares of Class A
common stock held by the Family Limited Partnerships. Mr. Watson may also be
deemed to beneficially own all of the shares of Class A common stock held by
the Trusts. Also includes 3,824,988 shares of Class A common stock issuable
upon the exercise of employee stock options held by Mr. Watson. The number
of shares does not include approximately 6,363 shares of Class A common
stock held by the Trustee of the Dynegy 401(k) Plan as of September 30, 2001
for the account of Mr. Watson. Participants in the Dynegy 401(k) Plan have
no voting or investment power with respect to such shares until their
distribution to such participants upon termination of their employment. In
addition, Mr. Watson may elect to take cash in lieu of shares of Class A
common stock held in his Dynegy 401(k) Plan account upon termination of his
employment.

EXECUTIVE COMPENSATION

The following table sets forth certain information regarding the
compensation earned by the individual who serves as Illinois Power's Chief
Executive Officer and the four other most highly compensated executive officers
of Illinois Power at the end of 2000 (the "Named Executive Officers"), as well
as amounts earned by or awarded to certain of such individuals for services
rendered in all capacities to Illinois Power for the fiscal years of 1998 and
1999.

7
<Page>
SUMMARY COMPENSATION TABLE

<Table>
<Caption>
LONG-TERM
COMPENSATION AWARDS
------------------------
ANNUAL COMPENSATION RESTRICTED SECURITIES
NAME AND PRINCIPAL ----------------------- OTHER ANNUAL STOCK UNDERLYING ALL OTHER
POSITION YEAR SALARY(1) BONUS(2) COMPENSATION(3) AWARDS(4) OPTIONS(5) COMPENSATION(6)
------------------ -------- ------------ -------- --------------- ----------- ---------- ---------------

Stephen W. Bergstrom ... 2000(8) (9) (9) (9) (9) (9) (9)
Chief Executive
Officer(7)

Larry F. Altenbaumer ... 2000 $303,208 $485,000 $ -- $250,000 84,553 $ 5,250
President 1999 $259,125 $156,600 $ -- -- 35,120 $676,983
1998 $244,375 $ 9,855 $ -- $ 19,855 10,000 $ 2,500

David W. Butts ......... 2000 $254,938 $245,444 $ -- $ -- 41,491 $ 5,250
Executive Vice 1999 $168,750(13) $135,000 $ -- $ -- 47,400 $298,733
President 1998 $214,732 $ 4,441 $ -- $ 14,441 10,000 $ 2,339

Kathryn L. Patton ...... 2000(10) $176,750 $130,000 $45,943(11) $ -- 16,548 $ 25,500
Senior Vice President,
General Counsel and
Secretary

Peggy E. Carter ........ 2000(12) $112,371 $75,850 $ -- $ -- 3,129 $ 2,329
Vice President and
Controller
</Table>

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

(1) Salary amounts for Messrs. Altenbaumer and Butts include additional base
salary payments of $12,083 and $8,438, respectively, representing payment
for the period from September 1999, when they became executive officers of
Illinois Power, to February 1, 2000, the closing date of the Dynegy-Illinova
merger, covering the pro-rata difference between their new base salaries and
their final base salaries at Illinova. Salary amount for Ms. Carter includes
a similar payment of $7,560 relative to her promotion to Controller in
November 1999.

(2) Bonus amounts include bonuses earned in 1998, 1999 and 2000 which were paid
in 1999, 2000 and 2001, respectively. Bonus amounts for Messrs. Altenbaumer
and Butts for 1999 represent the cash portions of grants made to them under
Illinois Power's Executive Incentive Compensation Plan for 1999, including
amounts deferred under Illinois Power's Executive Deferred Compensation
Plan.

(3) Includes "Perquisites and Other Personal Benefits" if value is greater than
the lesser of $50,000 or 10% of the reported salary and bonus.

(4) For 2000, Mr. Altenbaumer received 10,696 shares of restricted Dynegy
Class A common stock valued at $23.38 per share. Such shares vest five years
from the date of grant. During such period, dividend equivalents will be
credited to Mr. Altenbaumer's account. For 1998, Messrs. Altenbaumer and
Butts received stock unit awards under Illinois Power's Executive Incentive
Compensation Plan. One-half of each year's award under this plan converted
into stock units representing shares of Illinova common stock (now Dynegy
Class A common stock) based on the closing price of such stock on the last
trading day of the award year. The other one-half of the award is cash and
is included under the "Bonus" column. Stock units awarded in a given year,
together with cash representing the accumulated dividend equivalents on
those stock units, became fully vested after a three-year holding period.
Stock units are converted into cash based on the closing price of the common
stock on the first trading day of the distribution year. Participants (or
beneficiaries of deceased participants) whose employment is terminated by
retirement on or after age 55, disability or death receive the present value
of all unpaid awards on the date of such termination. Participants whose
employment is terminated for reasons other than retirement, disability or
death forfeit all unvested awards. In the event of a termination of
employment within

8
<Page>
two years after a change in control of Illinova or any of its subsidiaries,
without good cause or by any participant for good reason, all awards become
fully vested and payable.

(5) Number of shares underlying options reflects the two-for-one stock split
effected by Dynegy Inc. in August 2000 and the .69 merger conversion ratio
used in the Dynegy-Illinova merger. Such number also includes options
granted in 2001 for 2000.

(6) The amounts included as "All Other Compensation" for 2000 represent
contributions to the Named Executive Officers' respective savings plan
accounts. The amounts included for Messrs. Altenbaumer and Butts for 1999
also include pre-severance payments under compensation plans that were
retired in connection with the Dynegy-Illinova merger.

(7) Mr. Bergstrom served as Illinois Power's only Chief Executive Officer for
the year 2000, as Illinois Power's previous Chief Executive Officer
terminated as such in December 1999.

(8) Mr. Bergstrom became an executive officer of Illinois Power in
February 2000.

(9) Mr. Bergstrom is not compensated by Illinois Power for services rendered as
its Chief Executive Officer. Mr. Bergstrom is compensated by Dynegy for
services rendered in all capacities to Dynegy and its affiliates, including
Illinois Power.

(10) Ms. Patton became an executive officer of Illinois Power in February 2000.

(11) Amount includes an aggregate annual allowance for living and car expenses
of $27,924 and $15,540 of reimbursements related to expenses incurred by
Ms. Patton in connection with her relocation to Illinois following the
Dynegy-Illinova merger.

(12) Ms. Carter became an executive officer of Illinois Power in February 2000.

(13) Reflects amounts paid to Mr. Butts by Illinois Power from March 1999
through December 1999. Mr. Butts was compensated by Illinova Energy Partners
for his employment with Illinova Energy Partners during January and
February 1999.

OPTION GRANTS IN 2000

The following table sets forth certain information with respect to Dynegy
stock option grants made to the Named Executive Officers during 2000 under the
Dynegy Inc. 2000 Long-Term Incentive Plan. Dynegy indirectly beneficially owns
all of the common stock of Illinois Power. No stock option appreciation rights
were granted during 2000.

9
<Page>
INDIVIDUAL GRANTS

<Table>
<Caption>
POTENTIAL REALIZABLE
VALUE AT ASSUMED
NUMBER OF ANNUAL RATES OF STOCK
SECURITIES % OF TOTAL PRICE APPRECIATION FOR
UNDERLYING OPTIONS GRANTED OPTION TERM(2)
OPTIONS TO EMPLOYEES EXERCISE PRICE EXPIRATION -----------------------
NAME GRANTED(1) IN 2000(1) $/SHARE(1) DATE 5% 10%
---- ---------- --------------- -------------- ---------- ---------- ----------

Stephen W. Bergstrom........ (3) (3) (3) (3) (3) (3)
Larry F. Altenbaumer........ 25,218 * $23.38 2/2/10 $ 370,794 $ 939,666
59,335 * $47.19 2/19/11 $1,760,917 $4,462,509

David W. Butts.............. 22,728 * $23.38 2/2/10 $ 332,753 $ 843,262
18,763 * $47.19 2/19/11 $ 556,840 $1,411,141

Kathryn L. Patton........... 16,548 * $47.19 2/19/11 $ 491,104 $1,244,554

Peggy E. Carter............. 3,129 * $47.19 2/19/11 $ 92,861 $ 235,328
</Table>

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

* Less than 1%.

(1) Number of securities underlying options/exercise price reflects the
two-for-one stock split effected by Dynegy in August 2000 and the .69 merger
conversion ratio used in the Dynegy-Illinova merger. Such number also
reflects options granted to the Named Executive Officers in 2001 for 2000.
Percent of total options granted to employees reflects the number of Dynegy
stock options granted to employees of Dynegy and its affiliates, including
Illinois Power, in 2000.

(2) The dollar amounts under these columns represent the potential realizable
value of each grant of options assuming that the market price of Dynegy
Class A common stock appreciates in value from the date of grant at the 5%
and 10% annual rates prescribed by the Securities and Exchange Commission,
or SEC, and are not intended to forecast possible future appreciation, if
any, of the price of Dynegy Class A common stock.

(3) Mr. Bergstrom is not compensated by Illinois Power for services rendered as
its Chief Executive Officer. Mr. Bergstrom is compensated by Dynegy for
services rendered in all capacities to Dynegy and its affiliates, including
Illinois Power.

AGGREGATED OPTION EXERCISES AND FISCAL YEAR-END OPTION VALUES

The following table sets forth certain information regarding Dynegy stock
options held by the Named Executive Officers at December 31, 2000.
<Table>
<Caption>
NUMBER OF SECURITIES UNDERLYING
UNEXERCISED
SHARES OPTIONS AT FISCAL YEAR-END(1)
ACQUIRED VALUE ---------------------------------
NAME ON EXERCISE REALIZED EXERCISABLE UNEXERCISABLE
---- ----------- ------------- -------------- -------------

Stephen W. Bergstrom... (3) (3) (3) (3)
Larry F. Altenbaumer... 38,600 $1,244,863 76,206 60,812
David W. Butts......... 41,800 $1,327,391 53,976 45,152
Kathryn L. Patton...... 1,900 $ 89,182 27,415 8,830
Peggy E. Carter........ 0 $ 0 0 6,000

<Caption>
VALUE OF UNEXERCISED
IN-THE-MONEY OPTIONS
AT FISCAL YEAR-END(2)
--------------------------------
NAME EXERCISABLE UNEXERCISABLE
---- ------------- -------------

Stephen W. Bergstrom... (3) (3)
Larry F. Altenbaumer... $3,151,415 $2,541,189
David W. Butts......... $2,190,747 $2,144,693
Kathryn L. Patton...... $1,199,340 $ 348,277
Peggy E. Carter........ $ 0 $ 243,015
</Table>

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

(1) Number of shares underlying options reflects the two-for-one stock split
effected by Dynegy in August 2000 and the .69 merger conversion ratio used
in the Dynegy-Illinova merger. Certain unexercisable options held by
Messrs. Altenbaumer and Butts and Ms. Patton became fully vested and
exercisable effective upon the closing of the merger on February 1, 2000.

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<Page>
(2) Value based on the closing price of $56.0625 on the New York Stock
Exchange--Composite Tape for Dynegy Class A common stock on December 29,
2000.

PENSION BENEFITS

The following table shows the estimated annual pension benefits on a
straight life annuity basis payable on retirement to Messrs. Altenbaumer and
Butts and Ms. Carter based on specified annual average earnings and years of
credited service classifications, assuming continuation of the Illinois Power
Retirement Income Plan for Salaried Employees (the "Illinois Power Retirement
Plan") and employment until age 65. Estimated annual benefits under the Illinois
Power Retirement Plan are payable only with respect to annual earnings up to
$170,000. This table does not show the Social Security offset, but any actual
pension benefit payments would be subject to this offset.

<Table>
<Caption>
ESTIMATED ANNUAL BENEFITS (ROUNDED)
------------------------------------------------------------
15 YEARS 20 YEARS 25 YEARS 30 YEARS
ANNUAL CREDITED CREDITED CREDITED CREDITED
AVERAGE EARNINGS SERVICE SERVICE SERVICE SERVICE
---------------- -------- -------- -------- --------

$125,000 $37,500 $50,000 $62,500 $75,000
------- ------- ------- -------

150,000 45,000 60,000 75,000 90,000
------- ------- ------- -------

170,000 51,000 68,000 85,000 102,000
</Table>

The earnings used in determining pension benefits under the Illinois Power
Retirement Plan are the participants' regular base compensation, as set forth
under the "Salary" column in the Summary Compensation Table above.

At December 31, 2000, for purposes of the Illinois Power Retirement Plan,
Messrs. Altenbaumer and Butts and Ms. Carter had completed 28, 22 and 16 years
of credited service, respectively. None of the other Named Executive Officers
participate in the Illinois Power Retirement Plan.

EMPLOYMENT CONTRACTS AND CHANGE-IN-CONTROL ARRANGEMENTS

Dynegy has employment agreements with each of Messrs. Altenbaumer,
Bergstrom, Butts and Doty, and Ms. Patton. The employment agreements for Messrs.
Altenbaumer and Butts and Ms. Patton are described below. The employment
agreements for Messrs. Bergstrom and Doty are described in Dynegy's proxy
statement for its 2001 Annual Meeting of Shareholders.

LARRY ALTENBAUMER EMPLOYMENT AGREEMENT. Effective upon the closing of the
Dynegy-Illinova merger on February 1, 2000, Dynegy entered into a three-year
employment agreement with Mr. Altenbaumer, pursuant to which Mr. Altenbaumer
serves as President of Illinois Power and Senior Vice President of Dynegy. The
term of the agreement will automatically be extended for additional one-year
periods unless either party elects otherwise. Mr. Altenbaumer's employment
agreement entitles him to a base salary of $290,000, subject to increase at the
discretion of the Board of Directors, and the annual opportunity to earn
additional bonus amounts. Upon the closing of the merger, Mr. Altenbaumer also
was awarded grants of Dynegy stock options under the Dynegy Inc. 2000 Long Term
Incentive Plan with a value equal to 150% of his base salary and restricted
stock with an in-the-money value equal to approximately $250,000. Under the
terms of the employment agreement, all options granted to Mr. Altenbaumer prior
to November 1, 1999 became fully vested as of February 1, 2000. The

11
<Page>
employment agreement also contains non-compete provisions in the event of
Mr. Altenbaumer's termination of employment.

Mr. Altenbaumer's employment agreement also includes provisions governing
the payment of severance benefits if his employment is terminated due to
resignation following a "constructive termination," as defined in the agreement,
or for any other reason other than his voluntary resignation, death, disability
or discharge for cause. Any such severance benefits shall be made as follows:
(i) a lump sum amount equal to the product of (a) 2.99 and (b) the greater of
(1) the average annual base salary and incentive compensation paid to
Mr. Altenbaumer for the highest three calendar years preceding the year of
termination, and (2) Mr. Altenbaumer's base salary and target bonus amount for
the year of termination; (ii) a lump sum amount equal to the present value, as
defined by Dynegy's Board of Directors, of the senior management benefits and
other perquisites otherwise owed to Mr. Altenbaumer through the remaining term
of his employment; (iii) vesting of any previously granted unvested Dynegy stock
options to be exercised until the later of the term of his agreement and the
one-year anniversary of the termination date; and (iv) continued health and
welfare benefits for 36 months from the termination date.

DAVID W. BUTTS EMPLOYMENT AGREEMENT. Effective upon the closing of the
Dynegy-Illinova merger on February 1, 2000, Dynegy entered into a three-year
employment agreement with Mr. Butts, pursuant to which Mr. Butts serves as
Executive Vice President of Illinois Power and Vice President of Dynegy. The
term of the agreement will automatically be extended for additional one-year
periods unless either party elects otherwise. Mr. Butts' employment agreement
entitles him to a base salary of $245,000, subject to increase at the discretion
of the Board of Directors, and the annual opportunity to earn additional bonus
amounts, dependent upon certain financial objectives, as a participant in
Dynegy's incentive compensation plan. Upon the closing of the merger, Mr. Butts
also was awarded grants of Dynegy stock options under the Dynegy Inc. 2000 Long
Term Incentive Plan with a value equal to 160% of his base salary. Under the
terms of the employment agreement, all options granted to Mr. Butts prior to
November 1, 1999 became fully vested as of February 1, 2000. The employment
agreement also contains non-compete provisions in the event of Mr. Butts'
termination of employment.

Mr. Butts' employment agreement also includes provisions governing the
payment of severance benefits if his employment is terminated due to resignation
following a "constructive termination," as defined in the agreement, or for any
other reason other than his voluntary resignation, death, disability or
discharge for cause. Any such severance benefits shall be made as follows:
(i) a lump sum amount equal to the product of (a) 2.99 and (b) the greater of
(1) the average annual base salary and incentive compensation paid to Mr. Butts
for the highest three calendar years preceding the year of termination, and
(2) Mr. Butts' base salary and target bonus amount for the year of termination;
(ii) a lump sum amount equal to the present value, as defined by Dynegy's Board
of Directors, of the senior management benefits and other perquisites otherwise
owed to Mr. Butts through the remaining term of his employment; (iii) vesting of
any previously granted unvested Dynegy stock options to be exercised until the
later of the term of his agreement and the one-year anniversary of the
termination date; and (iv) continued health and welfare benefits for 36 months
from the termination date.

KATHRYN L. PATTON EMPLOYMENT AGREEMENT. Effective upon the closing of the
Dynegy-Illinova merger on February 1, 2000, Dynegy entered into a two-year
employment agreement with Ms. Patton, pursuant to which Ms. Patton serves as
Senior Vice President and General Counsel of Illinois Power. The term of the
agreement will automatically be extended for an additional one-year period
unless either party elects otherwise. Ms. Patton's employment agreement entitles
her to a base salary of $175,000, subject to increase at the discretion of the
Board of Directors, and the annual opportunity to earn additional bonus amounts,
dependent upon certain financial objectives, as a participant in Dynegy's
incentive compensation plan. Ms. Patton also is entitled to a housing and
automobile allowance of $2,327 per month during the original two-year term of
the agreement, after which she may request that she be returned to the Dynegy
organization in Houston, Texas as a Vice President at the same base salary and

12
<Page>
target bonus. If such request is not granted within 60 days, Ms. Patton may
terminate her employment and would be entitled to 18 months of base salary and
target bonus and vesting of any unvested options granted before December 31,
1999. Under the terms of the employment agreement, all options granted to
Ms. Patton prior to November 1, 1999 became fully vested as of February 1, 2000.
The employment agreement also contains non-compete provisions in the event of
Ms. Patton's termination of employment.

Ms. Patton's employment agreement also includes provisions governing the
payment of severance benefits if her employment is terminated due to resignation
following a "constructive termination," as defined in the agreement, or for any
other reason other than her voluntary resignation, death, disability or
discharge for cause. Any such severance benefits shall be made as follows:
(i) a lump sum amount equal to 150% of Ms. Patton's base salary and target bonus
amount for the year of termination; (ii) vesting of any previously granted
unvested Dynegy stock options to be exercised until the later of the term of her
agreement and the one-year anniversary of the termination date;
(iii) reimbursement of all reasonable out-of-pocket moving expenses from
Decatur, Illinois to Houston, Texas and assumption of liability through the end
of the contract term for Ms. Patton's housing and automobile leases in Decatur,
Illinois up to $2,327 per month; and (iv) continued health and welfare benefits
for 24 months from the termination date.

COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION

Dynegy and Illinois Power have a joint Compensation Committee that was
comprised of Dan Dienstbier (Chairman), Charles Bayless, D.W. Callahan and
Patricia Eckert during 2000. There are no matters relating to interlocks or
insider participation that Illinois Power is required to report.

13
<Page>
CERTAIN TRANSACTIONS

Illinois Power routinely conducts business with subsidiaries of Dynegy.
These transactions include the purchase or sale of electricity, natural gas and
transmission services as well as certain other services. Illinois Power derived
approximately $39.6 million in operating revenue from these transactions during
2000. Also, Illinois Power paid approximately $628.0 million, including
$557.9 million for power purchased, in operating expenses relating to such
transactions during 2000. All such transactions were conducted at prices and
terms similar to those available to and transacted with unrelated third parties.

With respect to electricity purchases, Illinois Power has a Power Purchase
Agreement ("PPA") with Dynegy Midwest Generation, Inc. ("DMG") that provides
Illinois Power the right to purchase power from DMG for a primary term extending
through December 31, 2004. The primary term may be extended annually, subject to
concurrence by both parties. The PPA defines the terms and conditions under
which DMG provides capacity and energy to Illinois Power pursuant to a tiered
pricing structure.

Effective January 1, 2000, the Dynegy consolidated group, which includes
Illinois Power, began operating under a Services and Facilities Agreement,
whereby other Dynegy affiliates exchange services with Illinois Power such as
financial, legal, information technology and human resources as well as shared
facility space. Illinois Power services are exchanged at fully distributed costs
and revenue is not recorded under this agreement.

Effective October 1, 1999, Illinois Power transferred its wholly owned
fossil generating assets and other generation-related assets and liabilities at
net book value to Illinova in exchange for an unsecured note receivable of
approximately $2.8 billion. Such assets subsequently were contributed by
Illinova to an affiliate that later became DMG. The note matures on
September 30, 2009 and bears interest at a rate of 7.5%, due semiannually in
April and October. At December 31, 2000, principal and accrued interest
outstanding under the note approximated $2.3 billion and $42.4 million,
respectively. Illinois Power recognized $174.9 million in interest income on the
note from Illinova in 2000.

SECTION 16(A) BENEFICIAL OWNERSHIP REPORTING COMPLIANCE

Section 16(a) of the Securities Exchange Act of 1934 requires Illinois
Power's officers and directors, and persons who beneficially own more than 10%
of Illinois Power's stock, to file reports of ownership and changes in ownership
with the SEC. The SEC has designated specific due dates for such reports and
Illinois Power must identify in this Information Statement those persons who did
not timely file such reports.

Illinois Power believes that its directors and officers, and persons who
beneficially own more than 10% of its stock, complied with all applicable filing
requirements pursuant to Section 16(a) during the fiscal year ended
December 31, 2000.

14
<Page>
INDEPENDENT AUDITORS

The Board of Directors of Illinois Power has selected Arthur Andersen LLP as
independent auditors for Illinois Power for 2001. A representative of that firm
will be present at the Annual Meeting and available to make a statement and to
respond to questions.

CHANGE IN INDEPENDENT AUDITORS

On February 1, 2000, Illinois Power dismissed its prior independent
accountants, PricewaterhouseCoopers LLP ("PwC"), upon completion of PwC's audit
of the financial statements of Illinois Power as of and for the year ended
December 31, 1999. Illinois Power filed its financial statements as of and for
the years ended December 31, 1999 and 1998 with the SEC on March 30, 2000. PwC's
reports on the financial statements of Illinois Power as of and for the years
ended December 31, 1999 and 1998 contained no adverse opinion or disclaimer of
opinion, and were not qualified or modified as to uncertainty, audit scope or
accounting principle. However, such reports contained explanatory paragraphs
discussing (a) the Dynegy-Illinova merger on February 1, 2000, (b) the 1998
impairment of long-lived assets due to a commitment to exit nuclear operations,
(c) a quasi-reorganization effected in December 1998, (d) the 1998 adoption of
the provisions of Statement of Financial Accounting Standards No. 133,
"Accounting for Derivatives and Hedging Activities" and Emerging Issues Task
Force Statement 98-10, "Accounting for Energy Trading and Risk Management
Activities" and (e) the discontinuance during 1997 in applying the provisions of
Statement of Financial Accounting Standards No. 71, "Accounting for the Effects
of Certain Types of Regulation" for the generation segment of the business of
Illinois Power. The decision to change accountants was approved by the Board of
Directors of Illinois Power.

In connection with its audits of the financial statements of Illinois Power
as of and for the years ended December 31, 1999 and 1998 and through March 30,
2000, there were no disagreements between PwC and Illinois Power on any matter
of accounting principles or practices, financial statement disclosure, or
auditing scope or procedure, which disagreements, if not resolved to the
satisfaction of PwC, would have caused them to make reference to the subject
matter of the disagreements in connection with their reports on the financial
statements of Illinois Power as of and for the years ended December 31, 1999 and
1998.

None of the "reportable events" described in Item 304(a)(1)(v) of
Regulation S-K occurred with respect to Illinois Power within the years ended
December 31, 1999 and 1998 and through March 30, 2000. Illinois Power requested
that PwC furnish them with a letter addressed to the SEC stating whether or not
it agrees with the above statements. Illinois Power filed a copy of such letter
agreeing with such statements with the SEC on April 6, 2000 as an exhibit to a
Current Report on Form 8-K/A.

On February 1, 2000, Illinois Power engaged Arthur Andersen LLP as its new
independent accountants. During the years ended December 31, 1999 and 1998 and
through March 30, 2000, Illinois Power did not consult Arthur Andersen LLP
regarding either (i) the application of accounting principles to a specified
transaction, either completed or proposed, or the type of audit opinion that
might be rendered on the financial statements of Illinois Power, and either a
written report or oral advice was provided to Illinois Power that Arthur
Andersen concluded was an important factor considered by Illinois Power in
reaching a decision as to the accounting, auditing or financial issue; or
(ii) any matter that was either the subject of a disagreement, as that term is
defined in Item 304(a)(1)(iv) of Regulation S-K and the related instructions to
Item 304 of Regulation S-K, or a reportable event, as that term is defined Item
304(a)(1)(v) of Regulation S-K.

15
<Page>
AUDIT FEES

Arthur Andersen LLP's aggregate fees billed for professional services
rendered for the audit of Illinois Power's annual financial statements for the
2000 fiscal year and the review of the financial statements included in the
Illinois Power's Forms 10-Q for the 2000 fiscal year were $658,000.

FINANCIAL INFORMATION SYSTEMS DESIGN AND IMPLEMENTATION FEES

Arthur Andersen LLP did not render any services with respect to Illinois
Power's financial information systems design and implementation for the fiscal
year 2000.

ALL OTHER FEES

Arthur Andersen LLP's fees for all other services rendered to Illinois Power
in 2000 were $491,000 and were charged primarily for mandatory regulatory
audits, internal audit work and treasury consulting services.

The Board of Directors has considered whether the Arthur Andersen LLP's
provision of non-audit services to Illinois Power is compatible with the
auditors' independence.

OTHER MATTERS

Copies of Illinois Power's Annual Report on Form 10-K filed with the SEC are
available to shareholders. One copy of Illinois Power's Annual Report on
Form 10-K for the year ended December 31, 2000 accompanies this Information
Statement. Requests for additional copies should be addressed to Illinois
Power's parent company at Dynegy Inc., Attention: Investor Relations, 1000
Louisiana, Suite 5800, Houston, Texas 77002.

Any proposal by a shareholder to be presented at the next Annual Meeting
must be received at Illinois Power's principal executive offices located at 500
South 27th Street, Decatur, Illinois 62521-2200, not later than July 1, 2002
unless the date for such Annual Meeting is changed by more than 30 days from the
date of this Annual Meeting, in which case the deadline for submitting a
shareholder proposal will be a reasonable time before Illinois Power begins to
print and mail the related proxy materials.

OTHER BUSINESS

Management does not know of any matter that will be presented for
consideration at the Annual Meeting other than the matters described in the
accompanying Notice of Annual Meeting of Shareholders.

By Order of the Board of Directors,

/s/ Kathryn L. Patton

Kathryn L. Patton
SENIOR VICE PRESIDENT, GENERAL COUNSEL
AND SECRETARY

Decatur, Illinois
October 29, 2001