Filed by Constellation Energy Group, Inc.

(Commission File No. 1-12869)

Pursuant to Rule 425 under the Securities Act of 1933

and deemed filed pursuant to Rule 14a-12 of the Securities Exchange Act of 1934

Subject Company: Constellation Energy Group, Inc.

(Commission File No. 1-12869)

On April 28, 2011, Constellation Energy made the following presentation to its employees relating to the proposed merger with Exelon Corporation.

Exelon and Constellation Energy Announce Merger

April 28, 2011

Creating a Clean, Competitive Future

Cautionary Statements Regarding Forward-Looking

Information

1

Except for the historical information contained herein, certain of the matters discussed in this communication

constitute “forward-looking statements” within the meaning of the Securities Act of 1933 and the Securities Exchange

Act of 1934, both as amended by the Private Securities Litigation Reform Act of 1995. Words such as “may,” “will,”

“anticipate,” “estimate,” “expect,” “project,” “intend,” “plan,” “believe,” “target,” “forecast,” and words and terms of

similar substance used in connection with any discussion of future plans, actions, or events identify forward-looking

statements. These forward-looking statements include, but are not limited to, statements regarding benefits of the

proposed merger, integration plans and expected synergies, the expected timing of completion of the transaction,

anticipated future financial and operating performance and results, including estimates for growth. These statements

are based on the current expectations of management of Exelon Corporation (Exelon) and Constellation Energy

Group, Inc. (Constellation), as applicable. There are a number of risks and uncertainties that could cause actual

results to differ materially from the forward-looking statements included in this communication. For example, (1) the

companies may be unable to obtain shareholder approvals required for the merger; (2) the companies may be

unable to obtain regulatory approvals required for the merger, or required regulatory approvals may delay the merger

or result in the imposition of conditions that could have a material adverse effect on the combined company or cause

the companies to abandon the merger; (3) conditions to the closing of the merger may not be satisfied; (4) an

unsolicited offer of another company to acquire assets or capital stock of Exelon or Constellation could interfere with

the merger; (5) problems may arise in successfully integrating the businesses of the companies, which may result in

the combined company not operating as effectively and efficiently as expected; (6) the combined company may be

unable to achieve cost-cutting synergies or it may take longer than expected to achieve those synergies; (7) the

merger may involve unexpected costs, unexpected liabilities or unexpected delays, or the effects of purchase

accounting may be different from the companies’ expectations; (8) the credit ratings of the combined company or its

subsidiaries may be different from what the companies expect; (9) the businesses of the companies may suffer as a

result of uncertainty surrounding the merger; 

2

Cautionary Statements Regarding Forward-Looking

Information (Continued)

(10)the companies may not realize the values expected to be obtained for properties expected or required to be

divested; (11) the industry may be subject to future regulatory or legislative actions that could adversely affect the

companies; and (12) the companies may be adversely affected by other economic, business, and/or competitive

factors. Other unknown or unpredictable factors could also have material adverse effects on future results,

performance or achievements of the combined company. Discussions of some of these other important factors and

assumptions are contained in Exelon’s and Constellation’s respective filings with the Securities and Exchange

Commission (SEC), and available at the SEC’s website at www.sec.gov, including: (1)  Exelon’s 2010 Annual Report

on Form 10-K in (a) ITEM 1A. Risk Factors, (b) ITEM 7. Management’s Discussion and Analysis of Financial

Condition and Results of Operations and (c) ITEM 8. Financial Statements and Supplementary Data: Note 18;

(2)  Exelon’s Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2011 in (a) Part II, Other

Information, ITEM 1A. Risk Factors, (b) Part 1, Financial Information, ITEM 2. Management’s Discussion and

Analysis of Financial Condition and Results of Operations and (c) Part I, Financial Information, ITEM 1. Financial

Statements: Note 12; and (3)  Constellation’s 2010 Annual Report on Form 10-K in (a) ITEM 1A. Risk Factors, (b)

ITEM 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations and (c) ITEM 8.

Financial Statements and Supplementary Data: Note 12. These risks, as well as other risks associated with the

proposed merger, will be more fully discussed in the joint proxy statement/prospectus that will be included in the

Registration Statement on Form S-4 that Exelon will file with the SEC in connection with the proposed merger.  In

light of these risks, uncertainties, assumptions and factors, the forward-looking events discussed in this

communication may not occur. Readers are cautioned not to place undue reliance on these forward-looking

statements, which speak only as of the date of this communication. Neither Exelon nor Constellation undertake any

obligation to publicly release any revision to its forward-looking statements to reflect events or circumstances after

the date of this communication.

Additional Information and Where to Find It

3

This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities, or a solicitation

of any vote or approval, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale

would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction.  Exelon intends to

file with the SEC a registration statement on Form S-4 that will include a joint proxy statement/prospectus and other

relevant documents to be mailed by Exelon and Constellation to their respective security holders in connection with the

proposed merger of Exelon and Constellation. WE URGE INVESTORS AND SECURITY HOLDERS TO READ THE

JOINT PROXY STATEMENT/PROSPECTUS AND ANY OTHER RELEVANT DOCUMENTS WHEN THEY BECOME

AVAILABLE, BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION about Exelon, Constellation and the

proposed merger.  Investors and security holders will be able to obtain these materials (when they are available) and

other documents filed with the SEC free of charge at the SEC's website, www.sec.gov.  In addition, a copy of the joint

proxy statement/prospectus (when it becomes available) may be obtained free of charge from Exelon Corporation,

Investor Relations, 10 South Dearborn Street, P.O. Box 805398, Chicago, Illinois 60680-5398, or from Constellation

Energy Group, Inc., Investor Relations, 100 Constellation Way, Suite 600C, Baltimore, MD 21202. Investors and security

holders may also read and copy any reports, statements and other information filed by Exelon, or Constellation, with the

SEC, at the SEC public reference room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-

SEC-0330 or visit the SEC’s website for further information on its public reference room.

Participants in the Merger Solicitation

Exelon, Constellation, and their respective directors, executive officers and certain other members of management and

employees may be deemed to be participants in the solicitation of proxies in respect of the proposed transaction.

Information regarding Exelon’s directors and executive officers is available in its proxy statement filed with the SEC by

Exelon on March 24, 2011 in connection with its 2011 annual meeting of shareholders, and information regarding

Constellation’s directors and executive officers is available in its proxy statement filed with the SEC by Constellation on

April 15, 2011 in connection with its 2011 annual meeting of shareholders. Other information regarding the participants in

the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, will be

contained in the joint proxy statement/prospectus and other relevant materials to be filed with the SEC when they become

available.

Creating Value Through a Strategic Merger

•

Delivers financial benefits to both sets of shareholders

•

Increases scale and scope of the business across the value chain

•

Matches the industry’s premier clean merchant generating fleet with the

leading retail and wholesale customer platform

•

Diversifies the generation portfolio

•

Continued upside to power market recovery

•

Maintains a strong regulated earnings profile with large urban utilities

Combining Exelon’s generation fleet and Constellation’s customer-facing

businesses creates a strong platform for growth and delivers benefits to

investors and customers

4

Combining Constellation’s leading competitive

businesses and Exelon’s clean generation…

Captures value across a range  

of market conditions

Directly links consumers of

electricity and generation

assets

Spreads credit risk across

more parties

Adds asset optimization

opportunities

Generation

Load

Optimizes cost structure by

reducing

3

rd

party

transactions

Reduces working capital

requirements and liquidity

needs

…Creates a platform for future growth and optimization of earnings and

cash flows

5

Scale, Scope and Flexibility Across the Value Chain

Upstream

Downstream

6

Reserves (gas)

266 bcf

Owned

Generating Capacity

34 GWs

(1)

Electric

Transmission

7,350 miles

Electric & Gas Dist.

6.6 million customers

Retail &

Wholesale Volumes

(2)

(Electric & Gas)

~165 TWh, 405 bcf

Note: Data as of 12/31/10 unless stated otherwise.

(1)   Generation capacity net of market mitigation assumed to be 2,648 MW consisting of Brandon Shores (1,273 MW), H.A. Wagner (976 MW) and CP Crane (399 MW).

(2)   Electric load includes all booked 2011E competitive retail sales, wholesale sales,and sales to load serving entities including ComEd swap. Gas 

        load includes all booked and forecasted 2011E competitive retail sales.

5.8

0.5

9.1

Exelon

Constellation

23.2

27.8

MISO (TWh)

PJM (TWh)

South

(1)

(TWh)

ISO-NE & NY ISO

(2)

(TWh)

West (TWh)

Load

Generation

31.8

42.8

147.3

58.7

Exelon

Constellation

4.8

27.1

9.1

Exelon

Constellation

Exelon

Constellation

2.4

0.4

0.4

Exelon

Constellation

Load

Generation

Generation

Load

Load

Generation

Load

Generation

6.3

9.1

101.5

179.1

27.8

23.2

27.1

13.9

2.4

0.8

Portfolio Matches Generation with Load in

Key Competitive Markets

The combination establishes an industry-leading platform with regional

diversification of the generation fleet

(1)

Represents load and generation in ERCOT, SERC and SPP.

(2)

Constellation load includes ~0.7TWh of load served in Ontario

Note: Data for Exelon and Constellation represents expected generation and load for 2011 as of 12/31/10.

Exelon load includes ComEd Swap, load sold through affiliates, fixed and indexed load sales and load sold through POLR auctions.

Constellation load includes load sold through affiliates, fixed and indexed load sales and load sold through POLR auctions. 

7

A Clean Generation Profile Creates Long-Term

Value in Competitive Markets

(1)   Net of market mitigation assumed to be 2,648 MW.

(2)

Constellation generation includes Boston Generation acquisition (2,950 MW of natural gas) and excludes Quail Run (~550 MW of natural gas).

Constellation nuclear reflects 50.01% interest in Constellation Energy Nuclear Group LLC.

Exelon Standalone

Total Generation: 25,619 MW

Constellation Standalone

(2)

Total Generation: 11,430 MW

Pro forma Company (Net of Mitigation)

(1)

Total Generation: 34,401 MW

8

Combined company remains the premier low-cost generator

Coal

6%

Oil

8%

Gas

11%

Hydro

6%

Wind/Solar/Other

3%

Nuclear

67%

Coal

24%

Nuclear

17%

Gas

52%

Wind/Solar/Other

2%

Hydro

3%

Oil

3%

Nuclear

55%

Coal

6%

Oil

7%

Gas

24%

Hydro

6%

Wind/Solar/

Other

2%

Expertise in Operating Regulated Utilities in

Large Metropolitan Areas

•

3.8 million electric customers

•

Service Territory: 11,300 square miles

•

Peak Load

(1)

: 23,613 MW

•

2011 Rate Base

(2)

: $9.3 billion

•

1.6 million electric customers

•

0.5 million gas customers

•

Service Territory: 2,100 square miles

•

Peak Load

(1)

: 8,932 MW

•

2011 Rate Base

(2)

: $5.0 billion

•

1.2 million electric customers

•

0.7 million gas customers

•

Service Territory: 2,300 square miles

•

Peak Load

(1)

: 7,198 MW

•

2011 Rate Base

(2)

: $3.9 billion

(1)

Peak load represents all-time peak load.

(2)

Estimated rate base as of end of year.

9

What Does This Mean to You

The combined company will create the nation’s leading competitive

energy supplier and America’s largest clean energy fleet

•

Growth will enable greater employee development opportunities

•

Pride in maintaining strong presence in Baltimore with new

headquarters for commercial and renewable energy businesses

located in newly built or renovated LEED Building

•

Continued commitment to the communities in which we live and

serve

(1)

Assumes potential mitigation requirements to be ~2,648 MW.

10

Our Commitment to You

We are committed to open, complete, frequent communication.

We will communicate with you when information is available. 

11

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