On

June

15,

2011,

Exelon

began

to

use

the

following

slides

concerning

the

proposed

merger

in

a

series

of

meetings

with

investors:

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)

Exelon and Constellation Energy Merger

Investor Meetings

June 2011

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;

1

Cautionary Statements Regarding

Forward-Looking Information (Continued)

2

(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 I, 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; (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; and (4)  Constellation’s Quarterly

Report on Form 10-Q for the quarterly period ended March 31, 2011 in (a) Part II, Other Information, ITEM 5.Other Information,

(b) Part I, 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: Notes to Consolidated Financial Statements, Commitments

and Contingencies.Theserisks,aswellasotherrisksassociatedwiththeproposedmerger,willbemorefullydiscussedinthe

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

•

$7 billion

•

$11 billion

•

11,980 (Total)

•

1,921 (Nuclear)

•

1.2 mil. (MD) 

•

0.7 mil. (MD)

•

44 states & D.C.

(5)

•

~106 TWh/yr

•

15% Generation

•

50% Utility

•

35% NewEnergy

Combination Will Result in Enhanced Scale,

Scope, Flexibility and Financial Strength

(1)  Market Value as of 6/1/11. Enterprise Value represents Market Value plus Net Debt as of 3/31/11.

(2)  Data as of 12/31/10. Exelon data includes 720 MW for Wolf Hollow.  Constellation data includes 2,950 MW for Boston Generation assets.

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

(4)  TWh/yr represents 2011 booked electric sales. Exelon load includes ComEd swap.

(5)  Competitive and wholesale business also active in Alberta, British Columbia and Ontario, Canada.

(6)

Exelon

EBITDA

estimates

per

equity

research.

Constellation

EBITDA

estimates

per

company

guidance.

Market  Value and

Enterprise

Value

(1)

Pro forma

Standalone

Owned

Generation

(in MW)

(2)

Regulated

Utilities

Competitive

Retail &

Wholesale

(4)

Business

Mix

(6)

•

$28 billion

•

$41 billion

•

26,339 (Total)

•

17,047 (Nuclear)

Electric customers

•

5.4 mil. (IL, PA)

Gas customers

•

0.5 mil. (PA)

•

4 states

•

~59

TWh/yr

2012E EBITDA

•

51% Generation

•

49% Utilities

•

$35 billion

•

$52 billion

•

44 states & D.C.

(5)

•

~165

TWh energy sales

•

Expect >50% pro forma EBITDA

from competitive business

•

35,671 (Total)

(3)

•

18,968 (Nuclear)

•

6.6 million electric & gas customers

in IL, PA and MD

5

Transaction Overview

•

100% stock –

0.930 shares of EXC for each share of CEG

•

Upfront

transaction

premium

of

18.1%

(1)

•

$2.10 per share Exelon dividend maintained

•

Expect to close in early 1Q 2012

•

Exelon and Constellation shareholder approvals in 3Q 2011

•

Regulatory approvals including FERC, DOJ, MD, NY, TX 

•

Executive Chairman: Mayo Shattuck

•

President and CEO: Chris Crane

•

Board of Directors: 16 total (12 from Exelon, 4 from Constellation)

•

Exelon Corporation

•

78% Exelon shareholders

•

22% Constellation shareholders

•

Corporate headquarters: Chicago, IL

•

Constellation headquarters: Baltimore, MD

•

No

change

to

utilities’

headquarters

•

Significant employee presence maintained in IL, PA and MD

Company Name

Consideration

Pro Forma

Ownership

Headquarters

Governance

Approvals &

Timing

(1)  Based on the 30-day average Exelon and Constellation closing stock prices as of April 27, 2011.

6

Exelon Transaction Rationale

•

Increases

geographic

diversity

of

generation,

load

and

customers

in

competitive     

markets

This transaction meets all of our M&A criteria and can be executed

Shared

Commitment to

Competitive

Markets

Enhances

Scalable Growth

Platform

Creates

Shareholder

Value

•

Expands a valuable channel to market our generation

•

Enhances margins in the competitive portfolio

•

Diversifies portfolio across the value chain

•

EPS break-even in 2012 and accretive by >5% in 2013

•

Maintains strong credit profile and financial discipline

•

Maintains earnings upside to future environmental regulations and power market

recovery

•

Adds stability to earnings and cash flow

7

•

Adds mix of clean generation to the portfolio

Clean

Generation Fleet

Constellation Transaction Rationale

•

Upfront premium of 18.1%

(1)

•

Dividend

accretion

of

103%

post-closing

•

Enhances

upside

to

power

market

recovery

and

synergies

The

transaction

creates

financial

and

strategic

value

that

is

consistent

with

Constellation’s

existing

strategy

Creates 

Shareholder

Value

•

Creates

balance

sheet

capacity

to

pursue

growth

opportunities

throughout

the

competitive

portfolio

•

Reduces

cost

of

capital

Balance Sheet

Strength

Complementary

Portfolios

•

Advances

strategy

of

matching

load

with

physical

generation

in

key

competitive

markets

•

Lowers

collateral

costs

of

competitive

businesses

8

(1)  Based on the 30-day average Exelon and Constellation closing stock prices as of April 27, 2011.

This Combination Is Good for Maryland

•

Maintains employee presence and platform for growth in Maryland

–

Exelon’s Power Team will be combined with Constellation’s wholesale and retail

business under the Constellation brand and will be headquartered

in Baltimore

–

Constellation and Exelon’s renewable energy business headquartered in Baltimore

–

BGE maintains independent operations headquartered in Baltimore

–

No involuntary merger-related job reductions at BGE for two years after close

•

Supports Maryland’s economic development and clean energy infrastructure

–

$10 million to spur development of electric vehicle infrastructure

–

$4 million to support EmPower Maryland Energy Efficiency Act

–

25 MWs of renewable energy development in Maryland

–

Charitable contributions maintained for at least 10 years

•

Provides direct benefits to BGE customers

–

$5 million provided for Maryland’s

Electric Universal Service Program (EUSP)

–

Over $110 million to BGE residential customers from $100 one-time rate credit

We will bring direct benefits to the State of Maryland, the City

of Baltimore and

BGE customers.  Total investment in excess of $250 million.

9

Transaction Timetable

2Q 2011

3Q 2011

4Q 2011

1Q 2012

Merger

Announcement

Make Regulatory

Filings

Mail Proxy

Materials

Exelon and

Constellation

Shareholder

Meetings

Secure Regulatory Approvals (including FERC, DOJ, Maryland, NRC,

New York and Texas)

Divestiture

Process

10

Status of Merger Approvals (as of 5/31/11)

11

Stakeholder

Status of Key Milestones

Filed

Approved

Shareholder

•

Plan to file S-4 Registration Statement June

2011

•

Shareholder approval: 3Q 2011

Department of Justice

(DOJ)

•

Submitted Hart-Scott-Rodino filing on May

31, 2011 for review under U.S. antitrust laws

Federal Energy

Regulatory Commission

(FERC)

•

Filed merger approval application and

related filings on May 20, 2011, which

assesses market power-related issues

Nuclear Regulatory

Commission

•

Filed for indirect transfer of Constellation

Energy licenses on May 12, 2011

Maryland

•

Filed for approval with the Maryland Public

Service Commission on May 25, 2011

New York

•

Filed for approval with the New York State

Public Service Commission on May 17, 2011

Texas

•

Filed for approval with the Public Utility

Commission of Texas on May 17, 2011

Transaction Economics Are Attractive for

Both Companies

•

Refined synergy run-rate and costs to achieve

estimates due to greater accessibility and availability of

data post-merger announcement  

–

Higher net O&M savings over 5 years of ~$50

million

•

Updated synergy run-rate of ~$310 million/year

–

Additional synergies primarily from corporate and

commercial consolidation

•

Total costs to achieve of ~$650 million

–

Incremental costs to achieve attributable to

employee related costs and transaction costs

12

Financial Metrics

•

EPS break-even in 2012 and accretive by >5% in 2013

•

Free cash flow accretive beginning in 2012

•

Lower consolidated liquidity requirements, resulting in cost savings

•

Investment-grade ratings and credit metrics

Synergies

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. 

13

A Clean Generation Profile Creates Long-Term

Value in Competitive Markets

(1)

Exelon

generation

includes

Wolf

Hollow

acquisition

(720

MW

of

natural

gas).

Constellation

generation

includes

Boston

Generation

acquisition

(2,950

MW

of

natural

gas).

Constellation

nuclear

reflects

50.01%

interest

in

Constellation

Energy

Nuclear

Group

LLC.

(2)

Net

of

physical

market

mitigation

assumed

to

be

2,648

MW.

Exelon Standalone

(1)

Total Generation: 26,339 MW

Constellation Standalone

(1)

Total Generation: 11,980 MW

Pro forma Company (Net of Mitigation)

(2)

Total Generation: 35,671 MW

14

Coal

5%

Oil

7%

Gas

13%

Hydro

7%

Wind/Solar/Other

3%

Nuclear

65%

Coal

23%

Nuclear

16%

Gas

54%

Wind/Solar/Other

2%

Hydro

2%

Oil

3%

Nuclear

53%

Coal

6%

Oil

6%

Gas

27%

Hydro

5%

Wind/Solar/

Other

3%

Combined company remains the premier low-cost generator

16%

34%

41%

9%

RTO

EMAAC

MAAC

SWMAAC

8%

15%

15%

63%

EMAAC

MAAC

RTO

SWMAAC

42%

7%

51%

RTO

MAAC

EMAAC

Increased Regional Diversity in PJM:

Capacity

Eligible

for

2014/15

RPM

Auction

(1)

2014/15

RPM

auction

results

were

announced

on

May

13

th

,

2011

Pro forma Company

4,390 MW

2,535 MW

9,230 MW

11,345 MW

Exelon Standalone

Constellation Standalone

(1)

All generation values are approximate and not inclusive of wholesale transactions; all capacity values are in installed capacity

terms (summer ratings) located in the areas and adjusted for mid-year PPA roll-offs.

8,700 MW

10,300 MW

1,500 MW

1,035 MW

4,390 MW

15

1,045 MW

530 MW

173

467

70

75

379

41

15

20

550

550

867

825

552

260

415

516

1,340

550

500

800

702

600

550

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2012

2013

2014

2015

2016

2017

2018

2019

2020

(in $M)

Constellation Regulated

Constellation Unregulated

Exelon Regulated

Exelon Unregulated

Ample Liquidity and Manageable

Debt Maturities

Sources of Liquidity

Debt

Maturity

Profile

(2012-2020)

(2)

•

Exelon & Constellation (excluding utilities)

currently have $10.3 billion of liquidity

•

Additional $2.2 billion of utility liquidity

•

Matching retail load and generation

reduces liquidity requirements for

combined company

•

$6.3B -

$7.3 billion

(1)

of liquidity provides

ample cushion

16

(in $B)

(1)

Based on preliminary analysis.

(2)

Debt maturity schedule as of 3/31/11, not including fair value swaps at Constellation Unregulated. Constellation Regulated debt balances include annual

transition

bond

payments

from

2012

–

2017.

(1)

~75% of 2012 –

2016 debt

maturities consist of

regulated utility debt

$6.1

$6.3 - $7.3

$3 - $4

$4.2

Existing liquidity

(ex-utilities)

Reduction in

existing liquidity

Pro forma liquidity

Constellation

Exelon

Pro forma