1

Filed by Exelon Corporation

(Commission File No.

1-16169)

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)

Beginning on April 28, 2011, Exelon used the following presentation in meetings

with employees of its Exelon Nuclear business unit.

Exelon Nuclear

and Constellation Energy

Nuclear Group 

Growing our Strength:

Safe and Reliable Electricity

All Hands Meeting

Friday, April 29, 2011

3

Exelon/Constellation –

The Merger

Merger is a great opportunity for Exelon.

We’re merging two leading companies into an

industry leader with many operating advantages.

EDF will be our partner in CENG’s

five units

The acquisition grows the nuclear fleet and allows

us to work closely with EDF.

This transaction will take some time to complete

4

EN/CENG

Exelon Nuclear

•

Largest U.S. nuclear fleet

•

Third largest in world

•

93.9% fleet capacity factor in 2010

•

8,700 employees

•

Excellent INPO safety performance

Constellation Energy NG

•

50.01% ownership by CENG

•

49.99% ownership stake by EDF

•

93.9% fleet capacity factor in 2010

•

2,700 employees

•

Excellent INPO safety performance

4

5

CENG at a Glance

Calvert Cliffs

Lusby, MD on the Eastern Shore

PWR, 2 units

1,750 megawatts (1975, 1977)

R.A. Ginna

Ontario, NY

PWR, 1 unit

581 megawatts (1970)

Nine Mile Point

Scriba, NY

BWR, 2 units

1,758 megawatts (1970, 1988)

Unit 2: CENG 82%, LIPA 18%

6

EDF at a Glance

World’s largest nuclear operator

Produces ~ 22% of EU electricity

Owns/Co-owns 30 nuclear sites

49.99% of CENG (5 reactors)

58 reactors in the French fleet

80% of British Energy (8 reactors)

Building 3 new plants in France

and Asia.

7

The Combined Companies

Combined nuclear assets

•

Solidifies position as largest U.S. nuclear operator

•

~ 19,000 megawatts

•

11,000+ employees

•

164 million megawatt-hours in 2010

•

13 sites, licensee of 22 reactors

•

IL, PA, NJ, NY & MD

Going forward

•

CENG structured as a separate operating group

•

Begin working relationship with EDF

•

Eventual HQ move to KS

8

Exelon

Corporation

Exelon

Generation

Company LLC

RF HoldCo

LLC

PECO

BGE

Constellation

NewEnergy

Inc.

Constellation

Energy

Nuclear Group

LLC

50.01%

ComEd

Note: For illustrative purposes only. Not intended to represent legal or organizational structure

After the Merger

Constellation

Energy Group

Inc

Fossil , Hydro

and Other

Generation

Exelon Energy

Delivery

Company LLC

Nuclear,

Fossil, Hydro,

Wind & Solar

Generation

27

9

Next Steps

Shareholder approval

•

Expected in Q3 2011

Regulatory approvals

•

Expected by end of Q4 2011

Transaction close in Q1 2012

•

Equity partnership with EDF to continue

•

Site/unit integration accelerates

Integration of companies

•

2012 -

2013

10

Key Takeaways

Great opportunity for Exelon

It will take time to close the deal

On-going communications will occur

Our focus MUST be on safety and reliability

Exelon Nuclear is

growing!

11

Questions?

12

Forward –Looking Information

Cautionary Statements Regarding Forward-Looking Information

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;

(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.

13

Forward –Looking Information

Additional Information and Where to Find It

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, 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.