<Page>
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 11-K
ANNUAL REPORT PURSUANT TO SECTION 15(d) OF
THE SECURITIES EXCHANGE ACT OF 1934
For the fiscal year ended December 31, 2000
Commission file number 1-3004
Illinois Power Company
Incentive Savings Plan for
Employees Covered Under a Collective
Bargaining Agreement
(Full title of the plan)
Dynegy Inc.
1000 Louisiana
Suite 5800
Houston, Texas 77002
(Name of issuer of the securities held
pursuant to the plan and the address
of its principal executive office.)
<Page>
ILLINOIS POWER COMPANY
INCENTIVE SAVINGS PLAN FOR EMPLOYEES
COVERED UNDER A COLLECTIVE BARGAINING AGREEMENT
INDEX TO FINANCIAL STATEMENTS AND ADDITIONAL INFORMATION
--------------------------------------------------------------------------------
PAGE
Financial Statements:
Report of Independent Accountants 1
Statement of Net Assets Available for Benefits
as of December 31, 2000 and 1999 2
Statement of Changes in Net Assets Available for
Benefits for the years ended December 31, 2000 and 1999 3
Notes to Financial Statements 4-11
Additional Information:
Schedule of Assets (Held at End of Year) Schedule I
December 31, 2000
Note: Other schedules required by 29 CFR 2520.103-10 of the Department of
Labor's Rules and Regulations for reporting and disclosure under ERISA
have been omitted because they are not applicable.
<Page>
REPORT OF INDEPENDENT ACCOUNTANTS
To the Participants and Administrator of
The Illinois Power Company
Incentive Savings Plan for Employees
Covered Under a Collective Bargaining Agreement
In our opinion, the accompanying statement of net assets available for benefits
and the related statement of changes in net assets available for benefits
present fairly, in all material respects, the net assets available for benefits
of the Illinois Power Company Incentive Savings Plan for Employees Covered under
a Collective Bargaining Agreement (the "Plan") at December 31, 2000 and 1999,
and the changes in net assets available for benefits for the years then ended in
conformity with accounting principles generally accepted in the United States of
America. These financial statements are the responsibility of the Plan's
management; our responsibility is to express an opinion on these financial
statements based on our audits. We conducted our audits of these statements in
accordance with auditing standards generally accepted in the United States of
America, which require that we plan and perform the audit to obtain reasonable
assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements, assessing the
accounting principles used and significant estimates made by management, and
evaluating the overall financial statement presentation. We believe that our
audits provide a reasonable basis for our opinion.
As explained in Note 1 to the financial statements, Illinois Power Company sold
its Clinton Nuclear Power Plant ("Clinton") to AmerGen Energy Company
("AmerGen") on December 15, 1999. Under terms of the sales agreement, Plan
account balances relating to Clinton employees were transferred to AmerGen on
January 21, 2000.
Our audits were conducted for the purpose of forming an opinion on the basic
financial statements taken as a whole. The supplemental Schedule of Assets (Held
at End of Year) is presented for the purpose of additional analysis and is not a
required part of the basic financial statements but is supplementary information
required by the Department of Labor's Rules and Regulations for Reporting and
Disclosure under the Employee Retirement Income Security Act of 1974. This
supplemental schedule has been subjected to the auditing procedures applied in
the audits of the basic financial statements and, in our opinion, is fairly
stated in all material respects in relation to the basic financial statements
taken as a whole.
PricewaterhouseCoopers LLP
September 28, 2001
<Page>
ILLINOIS POWER COMPANY
INCENTIVE SAVINGS PLAN FOR EMPLOYEES COVERED
UNDER A COLLECTIVE BARGAINING AGREEMENT
STATEMENT OF NET ASSETS AVAILABLE FOR BENEFITS
DECEMBER 31, 2000 AND 1999
--------------------------------------------------------------------------------
<Table>
<Caption>
DECEMBER 31,
2000 1999
Assets:
Cash and temporary cash investments $ 886,155 $ 413,130
Investments at fair value 181,482,741 138,924,171
Participant loans 3,148,746 3,761,671
------------ ------------
Total investments 185,517,642 143,098,972
------------ ------------
Dividends and interest receivable 4,338 1,007
Employee contributions receivable - 133,140
Employer contributions receivable 278,012 2,184,465
------------ ------------
282,350 2,318,612
------------ ------------
Total assets 185,799,992 145,417,584
------------ ------------
Liabilities:
Transfer to AmerGen (Note 1) - 22,008,635
------------ ------------
Total liabilities - 22,008,635
------------ ------------
Net assets available for benefits $185,799,992 $123,408,949
============ ============
</Table>
The accompanying notes are an integral part of the financial statements.
-2-
<Page>
ILLINOIS POWER COMPANY
INCENTIVE SAVINGS PLAN FOR EMPLOYEES COVERED
UNDER A COLLECTIVE BARGAINING AGREEMENT
STATEMENT OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS
FOR THE YEARS ENDED DECEMBER 31, 2000 AND 1999
--------------------------------------------------------------------------------
<Table>
<Caption>
YEAR ENDED
DECEMBER 31,
2000 1999
Sources of participants' equity:
Contributions:
Employee $ 6,471,746 $ 7,020,297
Employer 1,854,599 4,018,872
------------- ------------
8,326,345 11,039,169
------------- ------------
Investment income:
Dividend and interest income 11,874,155 11,622,423
Net appreciation in fair value of investments 52,166,418 19,727,546
------------- ------------
64,040,573 31,349,969
------------- ------------
Application of participants' equity:
Distributions to active and terminated participants 8,492,181 6,017,347
Administrative and miscellaneous expenses 22,777 50,633
------------- ------------
8,514,958 6,067,980
============= ============
Increase in net assets available for benefits
prior to interfund transfers 63,851,960 36,321,158
Plan-to-plan transfers - (626,204)
Transfer to AmerGen (Note 1) (1,460,917) (22,008,635)
Net assets available for benefits:
Beginning of year 123,408,949 109,722,630
------------- ------------
End of year $185,799,992 $123,408,949
============= ============
</Table>
The accompanying notes are an integral part of the financial statements.
-3-
<Page>
ILLINOIS POWER COMPANY
INCENTIVE SAVINGS PLAN FOR EMPLOYEES COVERED UNDER A
COLLECTIVE BARGAINING AGREEMENT
NOTES TO FINANCIAL STATEMENTS
DECEMBER 31, 2000
-------------------------------------------------------------------------------
1. DESCRIPTION OF PLAN
GENERAL
The Illinois Power Company Incentive Savings Plan for Employees Covered
Under a Collective Bargaining Agreement (the Plan) is sponsored and
administered by Illinois Power Company (the Company or Plan
Administrator). The Plan became effective as of January 1, 1987. Assets
of the Plan are held and managed by a trustee. Effective July 1, 1995,
Fidelity Management Trust Company of Boston, Massachusetts became trustee
and custodian. The purpose of the Plan is to enable participants to
invest a portion of their salaries in tax-deferred savings pursuant to
Section 401(k) of the Internal Revenue Code (IRC). The Plan is subject to
and in compliance with the provisions of the Employee Retirement Income
Security Act of 1974 (ERISA) as amended. On February 1, 2000 Illinova
Corporation, the parent company, merged with Dynegy Inc. No significant
changes have yet been made to the Plan as a result of the merger, except
for the one-for-one conversion of Illinova common stock into Dynegy
common stock on the effective date of the merger.
PARTICIPATION
All employees of the Company who are covered under a collective bargaining
agreement are eligible to participate in the Plan. Participation is
voluntary. Active participation ceases upon termination of employment with
the Company. Former employees can choose to liquidate their accounts or to
leave them in the Plan. Earnings will continue to accrue on undistributed
accounts. All accounts, whether for active or former employees, are fully
vested.
PLAN CHANGES AND AMENDMENTS
Effective January 1, 1999, the Company match contribution was increased.
The Company had previously matched 50% of the first $80 of the
participant's monthly before tax contributions and 25% of the balance of
the contributions for the month, up to 6% of the employee's base earnings
for the month. Effective January 1, 1999 the Company began matching 50% of
the participant's monthly before tax contributions, up to 6% of the
employee's base earnings for the month.
Effective December 15, 1999, Illinois Power sold its Clinton Nuclear Power
Plant to AmerGen Energy Company (AmerGen). Under terms of the sales
agreement, Plan account balances of $22,008,635 relating to Clinton
employees were transferred to AmerGen on January 21, 2000. Such amounts
were reflected as liabilities of the Plan at December 31, 1999 in the
Statement of Net Assets Available for Benefits. An additional $1,460,917
related primarily to incentive compensation contributions and participant
loans was later transferred to AmerGen during 2000 and is reflected as a
decrease to net assets available for benefits in the Statement of Changes
in Net Assets Available for Benefits for the year ended December 31, 2000.
AmerGen's plan would not accept transfer of the Fidelity Brokerage Link.
Employees who participated in this option were asked to liquidate their
accounts and transfer the funds to other funds or to the Fidelity
Retirement Money Market Fund. The trustee liquidated the accounts of
employees who did not comply with the request, and transferred the
proceeds to the Fidelity Retirement Money Market Fund. This fund is not
ordinarily an available option for contributions; it was used only to
facilitate the liquidation of the Brokerage Link accounts. At December 31,
2000 and 1999, the fund held $374 and $449,350, respectively.
-4-
<Page>
ILLINOIS POWER COMPANY
INCENTIVE SAVINGS PLAN FOR EMPLOYEES COVERED UNDER A
COLLECTIVE BARGAINING AGREEMENT
NOTES TO FINANCIAL STATEMENTS
DECEMBER 31, 2000
-------------------------------------------------------------------------------
CONTRIBUTIONS
Participants may make before-tax contributions by payroll deduction up to
the legal dollar limit. Participants may also make after-tax contributions
in cash or by payroll deduction. Total contributions are limited to the
applicable percentage limit set by law. A participant may also "roll-over"
into the Plan amounts previously invested in another retirement plan.
Participants have the option of investing their contributions in any or
all of the investment funds in the proportions they choose. They may
change their investment options or transfer amounts from fund to fund at
any time. Amounts are transferred to or from the Illinois Power Company
Incentive Savings Plan as participant's shift out of or into positions
covered by a collective bargaining agreement. These transfers are shown in
the Statement of Changes in Net Assets Available for Benefits as
plan-to-plan transfers.
The Company contributes a monthly match to the Plan equal to 50% of the
participants' monthly before-tax contributions per month, up to 6% of the
employee's base earnings for the month. All Company matching contributions
are made in units of Dynegy common sock and are contained in the Stock
Fund. Dividends on stock held in the Stock Fund are also invested in the
Stock Fund. See Note 5 for more information.
The Company has an Incentive Compensation arrangement in which all
participants employed by the Company on the last day of the Plan year are
eligible to earn cash and Dynegy stock if specified performance goals are
met. Units awarded under the Incentive Compensation arrangement are held
in the Stock Fund. Dividends earned on these units are also invested in
the Stock Fund.
Shares previously held in the Tax Reduction Act Stock Ownership Plan
(TRASOP), which was eliminated in 1988, are also held in the Stock Fund.
ESOP
In October 1990, the Board of Directors authorized amendments to the Plan
to provide for the implementation of an Employee Stock Ownership Plan
(ESOP) arrangement. Under this arrangement, the Company pursuant to
authorization granted by the Illinois Commerce Commission (ICC), loaned
$35 million to the Trustee of the ESOP in January 1991. The loan proceeds
were used to purchase 2,031,445 shares of the Company's common stock on
the open market. These shares are held in a suspense account under the
Plans and are being distributed to the accounts of participating employees
as the loan is repaid by the Trustee with Funds contributed by Illinois
Power, together with dividends on the shares acquired with the loan
proceeds. The shares are allocated to the accounts of eligible
participating employees as they are earned through the Match or Incentive
Compensation features of the Plan.
As of December 31, 2000 and 1999, 455,376 and 402,216 shares have been
allocated to bargaining unit employees for Matching Contributions and
Company Incentive Contributions, respectively.
-5-
<Page>
ILLINOIS POWER COMPANY
INCENTIVE SAVINGS PLAN FOR EMPLOYEES COVERED UNDER A
COLLECTIVE BARGAINING AGREEMENT
NOTES TO FINANCIAL STATEMENTS
DECEMBER 31, 2000
-------------------------------------------------------------------------------
DISTRIBUTIONS
Distributions as provided for in the Plan are made to retired Plan
participants or their beneficiaries. Distributions must begin by April 1st
of the calendar year following the later of the calendar year in which the
employee reaches age 70 1/2 or the calendar year in which the employee
retires. All distributions are made in the form of cash and/or Dynegy
common stock.
FORFEITURES
Each participant is responsible for supplying the Company with a current
address. If the address of the participant (or the participant's
beneficiary in the event of participant's death) is not known to the
Company within four years (three years in the event of participant's
death) of the date on which distribution may first be made, the adjusted
balance in the participant's account shall be deemed a forfeiture and
shall be used to reduce matching contributions and company incentive
contributions.
LOANS
The Plan allows participants to borrow from their before-tax accounts an
amount not to exceed the lesser of $50,000 reduced by the excess of the
highest outstanding balance of loans during the one-year period before the
date the loan is made over the outstanding balance of loans on the date
the loan is made or 50% of the vested account balance. Interest is charged
on these loans at a rate commensurate with interest rates charged by
persons in the business of lending money for similar type loans. For 2000,
the interest rate ranged from 9.50% to 10.50%, the rate for 1999 ranged
from 8.75% to 9.00%.
All loans made will mature and be payable in full no earlier than one year
and no later than five years from the date of the loan. An exception
exists when the loan is used by the participant to acquire his or her
principal residence. In this case, the loan will mature and be payable in
full no earlier than one year and no later than ten years from the date of
the loan. Loan repayments are made by payroll deductions authorized by the
participant and by optional cash payments. Interest paid on the loan is
credited to the participant's account. The Trustee maintains a Loan Fund
to hold the balances of participants' loans.
PLAN TERMINATION
The right to amend, modify or terminate the Plan is reserved by the
Company provided that such action does not retroactively and adversely
affect the rights of any participant or beneficiary under the Plan.
2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
BASIS OF ACCOUNTING
The accompanying Plan financial statements are prepared on the accrual
basis of accounting.
INVESTMENTS
Participant loans included in the loan fund are valued at cost, which
approximates fair value. Other investments are stated at current value
based on the latest quoted market price.
-6-
<Page>
ILLINOIS POWER COMPANY
INCENTIVE SAVINGS PLAN FOR EMPLOYEES COVERED UNDER A
COLLECTIVE BARGAINING AGREEMENT
NOTES TO FINANCIAL STATEMENTS
DECEMBER 31, 2000
-------------------------------------------------------------------------------
Investment securities are exposed to various risks, such as interest rate,
market, and credit. Due to the level of risk associated with certain
investment securities and the level of uncertainty related to changes in
the value of investment securities, it is at least reasonably possible
that changes in risks in the near term could materially affect the amounts
reported in the Statement of Net Assets Available for Benefits.
INCOME
Interest and dividend income is recorded as earned.
Net appreciation (depreciation) of investments is comprised of realized
and unrealized gains and losses. Realized gains or losses represent the
difference between proceeds received upon sale and the average cost of the
investment. Unrealized gain or loss is the difference between market value
and cost of investments retained in the Plan (at financial statement
date). For the purpose of allocation to participants, the Dynegy common
stock is valued by the Plan at market value on the date of allocation and
current value is used at the time of distribution to participants
resulting in a realized gain or loss and is reflected in the Net
Appreciation in Fair Value of Investments in the Statement of Changes in
Net Assets Available for Benefits.
EXPENSES
Certain expenses incurred in the administration of the Plan are paid by
the Plan rather than the Company. The expenses paid by the Plan include
ESOP record keeping fees and trustee administrative fees. All other
expenses incurred in the operation of the Plan are paid by the Company.
INCOME TAXES
The Internal Revenue Service has determined and informed the Company by a
letter dated January 8, 1996, that the Plan and related trust are designed
in accordance with applicable sections of the IRC. The plan has been
amended since receiving the determination letter. However, the Plan
Administrator and the Plan's tax counsel believe that the Plan is designed
and is currently being operated in compliance with the applicable
requirements of the IRC.
USE OF ESTIMATES
The preparation of financial statements in conformity with accounting
principles generally accepted in the United States of America requires
management to make estimates and assumptions that affect the reported
amounts of assets and liabilities at the date of the financial statements
and the reported amounts of revenues and expenses during the reporting
period. Actual results could differ from these estimates.
DISTRIBUTION OF BENEFITS
Distributions of benefits are recorded when paid.
-7-
<Page>
ILLINOIS POWER COMPANY
INCENTIVE SAVINGS PLAN FOR EMPLOYEES COVERED UNDER A
COLLECTIVE BARGAINING AGREEMENT
NOTES TO FINANCIAL STATEMENTS
DECEMBER 31, 2000
-------------------------------------------------------------------------------
3. INVESTMENTS
Plan investments are received, invested and held by the Trustee.
Individual investments that represents 5% or more of the Plan's net assets
available for benefits include:
<Table>
<Caption>
DECEMBER 31,
INVESTMENTS AT FAIR VALUE AS 2000
DETERMINED BY QUOTED MARKET PRICE FAIR VALUE
Dynegy Common Stock $ 90,448,602
Fidelity Equity Income Fund $ 19,097,945
Fidelity Independence Fund* $ 39,372,187
Fidelity Managed Income Portfolio $ 12,693,619
*Formerly Fidelity Retirement Growth Fund
DECEMBER 31,
INVESTMENTS AT FAIR VALUE AS 1999
DETERMINED BY QUOTED MARKET PRICE FAIR VALUE
Illinova Common Stock $ 31,131,900
Fidelity Equity Income Fund $ 23,122,056
Fidelity Retirement Growth Fund $ 43,717,865
Fidelity Managed Income Portfolio $ 15,176,985
</Table>
4. TRANSACTIONS WITH PARTIES-IN-INTEREST
Certain Plan investments are shares of mutual funds managed by Fidelity
Management Trust Company. Fidelity Management Trust Company is the trustee
as defined by the Plan and, therefore, these transactions qualify as
party-in-interest. Fees paid during the year for legal, accounting,
actuarial and other professional services rendered by parties-in-interest
were based on customary and reasonable rates for such services.
-8-
<Page>
ILLINOIS POWER COMPANY
INCENTIVE SAVINGS PLAN FOR EMPLOYEES COVERED
UNDER A COLLECTIVE BARGAINING AGREEMENT
NOTES TO FINANCIAL STATEMENTS
DECEMBER 31, 2000
-------------------------------------------------------------------------------
5. NONPARTICIPANT - DIRECTED INVESTMENTS
All funds in the plan are participant directed, with the exception of
the Stock Fund, which is partially nonparticipant-directed as pertains
to the Company match and incentive compensation features of the plan.
Information about the net assets and the significant components of the
changes in net assets relating to the Stock Fund is as follows:
<Table>
<Caption>
DECEMBER 31,
2000 1999
Assets:
Cash and temporary cash investments $ 626,340 $ 332,219
Investments at fair value 90,448,602 31,131,900
----------- -----------
Total investments 91,074,942 31,464,119
Dividends and interest receivable 4,338 1,007
Employee contributions receivable - 1,880
Employer contributions receivable 278,012 2,184,465
----------- -----------
282,350 2,187,352
----------- -----------
Total assets 91,357,292 33,651,471
----------- -----------
Liabilities:
Assets transferred to AmerGen - 5,137,664
----------- -----------
Total liabilities - 5,137,664
----------- -----------
Net assets available for benefits $91,357,292 $28,513,807
=========== ===========
</Table>
-9-
<Page>
ILLINOIS POWER COMPANY
INCENTIVE SAVINGS PLAN FOR EMPLOYEES COVERED
UNDER A COLLECTIVE BARGAINING AGREEMENT
NOTES TO FINANCIAL STATEMENTS
DECEMBER 31, 2000
--------------------------------------------------------------------------------
<Table>
<Caption>
DECEMBER 31,
2000 1999
Sources of participants' equity:
Contributions:
Employee $ 184,103 $ 107,121
Employer 1,854,486 4,018,872
----------- -----------
2,038,589 4,125,993
----------- -----------
Investment income:
Dividend and interest income 921,899 1,196,876
Net change in fair value of investments 62,767,763 9,142,534
----------- -----------
63,689,662 10,339,410
----------- -----------
Application of participants' equity:
Distributions to active and terminated participants 3,154,351 1,633,385
Administrative and miscellaneous expenses 1,947 28,318
----------- -----------
3,156,298 1,661,703
----------- -----------
Increase (decrease) in net assets available for benefits
prior to transfers 62,571,953 12,803,700
Loans to participants, net (46,111) (15,520)
Fund-to-fund transfers 819,510 (2,863,120)
Plan-to-plan transfers - (197,561)
Assets transferred to AmerGen (501,867) (5,137,664)
Net assets available for benefits:
Beginning of year 28,513,807 23,923,972
----------- -----------
End of year $91,357,292 $28,513,807
=========== ===========
</Table>
-10-
<Page>
ILLINOIS POWER COMPANY
INCENTIVE SAVINGS PLAN FOR EMPLOYEES COVERED
UNDER A COLLECTIVE BARGAINING AGREEMENT
<Table>
<Caption>
NOTES TO FINANCIAL STATEMENTS
DECEMBER 31, 2000
-------------------------------------------------------------------------------------------------------------------------
6. RECONCILIATION OF FINANCIAL STATEMENTS TO FORM 5500
The following is a reconciliation of net assets available for
benefits per the financial statements to Form 5500:
DECEMBER 31,
2000 1999
Net assets available for benefits per the
financial statements $ 185,799,992 $ 123,408,949
Accrued distributions of benefits 73,238 -
------------- -------------
Net assets available for benefits per the Form 5500 $ 185,726,754 $ 123,408,949
============= =============
</Table>
The following is a reconciliation of benefits distributed to
participants per the financial statements to the Form 5500:
<Table>
<Caption>
YEAR ENDED
DECEMBER 31,
2000
Distribution of benefits per the financial statements $ 8,492,181
Add: accrued distribution of benefits at December 31, 2000 73,238
Less: accrued distribution of benefits at December 31, 1999 -
-------------
Distribution of benefits per the Form 5500 $ 8,565,419
=============
</Table>
-11-
<Page>
<Table>
<Caption>
ILLINOIS POWER COMPANY SCHEDULE I
INCENTIVE SAVINGS PLAN FOR EMPLOYEES COVERED
UNDER A COLLECTIVE BARGAINING AGREEMENT
SCHEDULE OF ASSETS (HELD AT END OF YEAR)
DECEMBER 31, 2000
-------------------------------------------------------------------------------------------------------------------------
IDENTITY OF ISSUE/ FAIR
DESCRIPTION OF INVESTMENT COST VALUE
*Dynegy Common Stock $ 21,137,950 $ 90,448,602
*Fidelity Equity Income Fund 15,630,407 19,097,945
*Fidelity Independence Fund 37,050,178 39,372,187
*Fidelity Asset Manager Income Fund 610,848 599,990
*Fidelity Asset Manager Growth Fund 3,684,998 3,398,823
*Fidelity Asset Manager Fund 5,086,418 5,033,185
*Fidelity International Growth and Income Fund 2,041,365 1,997,602
*Fidelity Managed Income Portfolio Fund 12,693,619 12,693,619
*Fidelity US Equity Index Commingled Pool 3,142,154 3,603,189
*Founders Growth Fund 3,053,959 2,114,028
*USAA International Fund 330,114 302,792
*Warburg Pincus Emerging Growth 1,407,824 1,111,335
*Fidelity Brokerage Link 1,709,070 1,709,070
*Fidelity Retirement Money Market Fund 374 374
*Participant Loans** 3,148,746 3,148,746
------------ ------------
$110,728,024 $184,631,487
============ ============
</Table>
* A party-in-interest to the plan
** Interest rates on loans range from 9.5% to 10.5%
<Page>
Signature
Pursuant to the requirements of the Securities Exchange Act of 1934, Illinois
Power Company has duly caused this annual report to be signed on its behalf of
the undersigned hereunto duly authorized.
Illinois Power Company
Incentive Savings Plan
For Employees Covered Under a
Collective Bargaining Agreement
By: /s/ Ron Oliver
--------------------------------
Ron Oliver
Human Resources Transition Manager
Date: October 17, 2001
<Page>
EXHIBIT INDEX
EXHIBITS FILED HEREWITH
Exhibit No. Description
--------------------------------------------------------------------------------
1 Consent of Independent Accountants