As filed with the Securities and Exchange Commission on March 15, 2005 File No. 70-______

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

(Name of companies filing this statement and address of principal executive office)

Exelon Corporation

(Name of top registered holding company)

(Name and address of agent for service)

The Commission is requested to send copies of all notices, orders and communications in connection
with this Application-Declaration to:

TABLE OF CONTENTS

 i 

 ii 

Item 1. Description of Proposed Transaction

     A. Introduction.

     In this Form U-1 application/declaration (this “Application”), Applicants are seeking approval pursuant to Sections 6(a), 7, 8, 9, 10, 12, 13, 32 and 33 of the Public Utility Holding Company Act of 1935 (the “Act”) and the rules thereunder to engage in various transactions related to the merger of Exelon Corporation (“Exelon”) and Public Service Enterprise Group Incorporated (“PSEG”), as described more fully herein.¹

     On December 20, 2004, Exelon and PSEG, an electric and gas utility holding company that claims exemption from registration pursuant to Rule 2 under Section 3(a)(1) of the Act, entered into an Agreement and Plan of Merger (the “Merger Agreement”).² Pursuant to the terms of the Merger Agreement, PSEG will merge into Exelon (the “Merger”), thereby ending the separate corporate existence of PSEG. Each PSEG shareholder will be entitled to receive 1.225 shares of Exelon common stock for each PSEG share held and cash in lieu of any fraction of an Exelon share that a PSEG shareholder would have otherwise been entitled to receive. Exelon common stock will be unaffected by the Merger, with each issued and outstanding share remaining outstanding following the Merger as a share in the surviving company. Upon completion of the Merger, Exelon will change its name to Exelon Electric & Gas Corporation.³

     As the surviving company in the Merger, Exelon will remain the ultimate corporate parent of PECO Energy Company (“PECO”) and Commonwealth Edison Company (“ComEd”) and the other Exelon subsidiaries and become the ultimate corporate parent of Public Service Electric and Gas Company (“PSE&G”), a public utility company under the Act, and the other PSEG subsidiaries.

     Exelon will continue to be a registered public utility holding company under the Act, and ComEd, PECO and PSE&G will continue to be operating franchised utility companies. Exelon will remain headquartered in Chicago but will also have energy trading and nuclear headquarters in southeastern Pennsylvania and generation headquarters in Newark, New Jersey. PSE&G will remain headquartered in Newark. PECO will remain headquartered in Philadelphia and ComEd will remain headquartered in Chicago.

     The Merger is subject to a number of usual and customary conditions precedent, including receipt by the parties of required state and federal regulatory approvals and filing of pre-merger notification statements under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (“HSR Act”), and the expiration or termination of the statutory waiting period thereunder. (See Item 4 - Regulatory Approvals.) The boards of directors of Exelon and PSEG have approved the proposed Merger, which will also require approval of the issuance of shares of common stock by Exelon required by the Merger Agreement by the shareholders of Exelon and approval of the Merger by the shareholders of PSEG.

     In addition to the changes resulting from the Merger Agreement, the Applicants intend to revise their corporate structure (the “Exelon Generation Restructuring”). Although their plans are not yet completely finalized, the Applicants currently propose to implement the following changes, subject to approval, as required, by the Securities and Exchange Commission (the “Commission”). After obtaining

1

necessary approvals and third party consents, PSEG Power LLC (“PSEG Power”) and its direct subsidiaries PSEG Nuclear LLC (“PSEG Nuclear”), PSEG Fossil LLC (“PSEG Fossil”) and PSEG Energy Resources & Trade LLC (“PSEG ER&T”) will all cease to exist as separate entities and will become part of Exelon Generation Company, LLC (“Exelon Generation”). The business functions of each of these former PSEG entities will become a part of the respective Exelon Generation business unit. It is anticipated that the subsidiaries owned by these PSEG entities will be retained as direct subsidiaries of Exelon Generation.

     Also in connection with the Merger, PSE&G will become a direct subsidiary of Exelon Energy Delivery Company, LLC (“Delivery”).⁴ The current subsidiaries of PSE&G will remain intact. PSEG Energy Holdings LLC (“PSEG Holdings”) will become a subsidiary of Exelon, as the successor to PSEG. The current subsidiaries of PSEG Holdings will remain intact. PSEG Services Corporation (“PSEG Services”) will sell all of its assets to Exelon Business Services Company (“Exelon BSC”), change its name, and remain as a non-energy subsidiary. Exelon BSC will be the sole “service company” of Exelon.

     A summary diagram depicting Exelon’s proposed post-Merger corporate structure is filed herewith as Exhibit G-1. Diagrams depicting the existing corporate structure of the Exelon system as well as the PSEG system are filed herewith as Exhibits G-2 and G-3, respectively.

     Exelon and PSEG have proposed a plan to mitigate any generation market concentration concerns resulting from the Merger, which calls for Exelon to divest certain generation capacity.⁵ The sale of this generation capacity will occur as soon as possible within 18 months following close of the Merger. Approval of the Commission will be required for the disposition of this generation capacity because, as a result of the Exelon Generation Restructuring, this generation capacity will be owned by Exelon Generation, a public utility under the Act. The disposition of generation capacity owed by Exelon Generation is referred to as the “Generation Divestiture.”⁶

     In addition to authorization of the Merger, the Exelon Generation Restructuring, and the Generation Divestiture, Applicants are requesting certain related approvals, including:

	1.	Authorizations related to service company and other affiliate transactions.
	2.	Issuance by Exelon of common stock in connection with the Merger and employee and director compensation plans as described below.
	3.	Authorization to the extent required of the consolidation (or replacement in lieu of consolidation) of existing indebtedness and obligations of PSEG and its subsidiaries as obligations of Exelon or its subsidiaries as a result of the Merger.
	4.	Necessary modifications to Exelon’s existing omnibus financing authority granted by order of April 1, 2004 in Holding Company Act Release No. 27830 (the “2004 Financing Order”).

     Applicants request that the Commission issue a final order granting the requested authority without an evidentiary hearing, as expeditiously as feasible, but no later than December 15, 2005.

2

     B. Description of Exelon and Its Subsidiaries

     1. Exelon, Generally

     Exelon was incorporated in Pennsylvania in February 1999. On October 20, 2000, Exelon became the ultimate parent corporation for PECO and ComEd, and registered pursuant to Section 5 of the Act.

     Exelon, through its subsidiaries, operates in three business segments - Delivery, Generation and Enterprises – as described below. In addition to Exelon’s three business segments, Exelon BSC, a subsidiary of Exelon, provides Exelon and its subsidiaries with financial, human resources, legal, information technology, supply management and corporate governance services, as well as direction and management of shared functions for Delivery.

     Delivery. Exelon’s energy delivery business consists of the purchase and sale of electricity and distribution and transmission services by ComEd in northern Illinois and by PECO in southeastern Pennsylvania and the purchase and sale of natural gas and distribution services by PECO in the Pennsylvania counties surrounding the City of Philadelphia.

     Generation. Exelon’s generation business consists of the owned and contracted for electric generating facilities and energy marketing operations of Exelon Generation, a 49.5% interest in two power stations in Mexico, and the competitive retail sales business of Exelon Energy Company.

     Enterprises. Exelon’s enterprise business consists primarily of the remaining infrastructure and electrical contracting services of Exelon Enterprises Company, LLC (“Enterprises”) and other investments weighted towards the communications and energy services industries. Exelon plans to divest or wind-down the remaining assets of Enterprises during 2005.

     2. The Exelon Utility Subsidiaries

     Exelon indirectly owns all of the issued and outstanding membership interests of Exelon Generation, all the issued and outstanding common stock of PECO and substantially all of the issued and outstanding common stock of ComEd,⁷ and ComEd owns all the issued and outstanding common stock of Commonwealth Edison Company of Indiana, Inc. (the “Indiana Company”) (together, the “Exelon Utility Subsidiaries”).

     PECO is engaged principally in the purchase, transmission, distribution and sale of electricity to residential, commercial and industrial customers in southeastern Pennsylvania and in the purchase, distribution and sale of natural gas to residential, commercial and industrial customers in the Pennsylvania counties surrounding the City of Philadelphia. PECO is subject to extensive regulation by the Pennsylvania Public Utility Commission (“PAPUC”) as to electric and gas rates, the issuances of certain securities and certain other aspects of PECO’s operations. PECO is also subject to regulation by the Federal Energy Regulatory Commission (“FERC”) as to transmission rates, gas pipelines and certain other aspects of its business.

     PECO’s retail service territory covers approximately 2,100 square miles in southeastern Pennsylvania. PECO provides electric delivery service in an area of approximately 2,000 square miles, with a population of approximately 3.8 million, including 1.5 million in the City of Philadelphia. Natural gas service is supplied in an approximately 1,900 square mile area in southeastern Pennsylvania adjacent to

3

Philadelphia, with a population of approximately 2.3 million. PECO delivers electricity to approximately 1.5 million customers and natural gas to approximately 460,000 customers.

     ComEd is engaged principally in the purchase, transmission, distribution and sale of electricity to a diverse base of residential, commercial, industrial and wholesale customers in northern Illinois. ComEd is subject to extensive regulation by the Illinois Commerce Commission (“ICC”) as to rates, the issuance of certain securities, and certain other aspects of ComEd’s operations. ComEd is also subject to regulation by the FERC as to transmission rates and certain other aspects of its business.

     ComEd’s retail service territory has an area of approximately 11,300 square miles and an estimated population of eight million. The service territory includes the City of Chicago, an area of about 225 square miles with an estimated population of three million. ComEd has approximately 3.7 million customers.

     Electric utility restructuring legislation was adopted in Pennsylvania in December 1996 and in Illinois in December 1997. Both Illinois and Pennsylvania permit competition by alternative generation suppliers for retail generation supply while transmission and distribution service remains fully regulated. Both states, through their regulatory agencies, established a phased approach for allowing customers to choose an alternative electric generation supplier, required rate reductions and imposed caps on rates during a transition period, and allowed the collection of competitive transition charges from customers to recover costs that might not otherwise be recovered in a competitive market.

     Effective as of January 1, 2001, Exelon effected a restructuring that involved the transfer of the electric generating assets of ComEd and PECO to Exelon Generation, a Pennsylvania limited liability company and a public utility company engaged in the generation, sale and purchase of electricity in Pennsylvania, Illinois and elsewhere and also engaged in the trading of other energy and energy-related commodities and development and ownership of exempt wholesale generators (“EWGs”).

     PJM Interconnection, L.L.C. (“PJM”) is the independent system operator and the FERC-approved Regional Transmission Organization (“RTO”) for the Mid-Atlantic and a portion of the Midwest. PJM is the transmission provider under, and the administrator of, the PJM Open Access Transmission Tariff, operates the PJM Interchange Energy Market and Capacity Credit Markets, and conducts the day-to-day operations of the bulk power system of the PJM region. ComEd’s and PECO’s transmission systems are currently under the control of PJM and, by order dated October 28, 2004 (Holding Co. Act Release No. 27904) (the “PJM Order”), the Commission found that the electric utility properties of the Exelon system satisfy the interconnection requirement of Section 2(a)(29)(A) of the Act by reason of PJM’s operational control of the transmission assets of ComEd and PECO.⁸

     Each of ComEd and PECO is a public utility company within the meaning of the Act. ComEd is also a holding company exempt from registration pursuant to Section 3(a)(1) of the Act, by reason of its ownership of the Indiana Company, which is a fourth public utility company subsidiary, with no retail operations. Delivery is an intermediate registered holding company and a first-tier subsidiary of Exelon. Delivery owns all of the issued and outstanding common stock of PECO and substantially all of the issued and outstanding common stock of ComEd. See Note 7.

     Exelon Generation is also an electric utility company within the meaning of the Act. Exelon Generation is a wholly owned subsidiary of Exelon Ventures Company, LLC (“Ventures”), which is an intermediate registered holding company and a first tier subsidiary of Exelon. Ventures and Delivery are

4

referred to herein as the “Other Registered Holding Companies.” None of the Other Registered Holding Companies has securities outstanding in the hands of the public.

     3. Direct Non-Utility Subsidiaries of Exelon

     Exelon has direct wholly owned non-utility subsidiaries (in addition to its direct, wholly owned registered holding company subsidiaries, Ventures and Delivery), as follows:

     Exelon BSC, a service company, provides administrative, management and technical services to Exelon and its associate companies;

     Exelon Investment Holdings, LLC, an Illinois limited liability company, is a holding company for tax-advantaged housing transactions;

     UII, LLC, an Illinois limited liability company, is engaged in a like-kind exchange transaction pursuant to which a portion of the proceeds from the sale of ComEd’s fossil generating stations was invested in passive generating station leases with entities unrelated to Exelon. The generating stations were leased back to such entities as part of the transaction.⁹

     Exelon has the following additional direct subsidiaries: Unicom Assurance Company, Ltd., an inactive captive insurance company, Exelon Capital Trust I, an inactive finance company, Exelon Capital Trust II, an inactive finance company and Exelon Capital Trust III, an inactive finance company.

     4. Capitalization of Exelon

     The total authorized shares of capital stock of Exelon consist of (i) 1,200,000,000 shares of common stock, no par value and (ii) 100,000,000 shares of preferred stock, no par value.¹⁰ At the close of business on December 31, 2004, 664,187,996 shares of Exelon common stock were outstanding, and no shares of Exelon preferred stock were issued and outstanding. In addition, at that date (i) 2,499,865 shares of common stock were held by Exelon in its treasury, (ii) 25,205,285 shares of common stock were reserved for issuance pursuant to outstanding options to purchase common stock granted under Exelon’s Long-Term Incentive Plan, Exelon’s Amended and Restated Long-Term Incentive Plan, as amended, and Exelon’s 1998 Stock Option Plan (together with Exelon’s Directors’ Stock Unit Plan, the “Exelon Stock Incentive Plans”), (iii) 14,777,078 shares of common stock were reserved for the grant of additional awards under the Exelon Stock Incentive Plans, (iv) 7,000,000 shares of common stock were reserved for issuance pursuant to the Dividend Reinvestment and Stock Purchase Plan, (v) 624,495 shares of common stock were reserved for issuance pursuant to outstanding performance shares, (vi) 216,000 shares of common stock were reserved for issuance pursuant to outstanding units under Exelon’s Directors’ Stock Unit Plan, (vii) 5,357,745 shares of common stock were reserved for issuance under Exelon’s Employee Stock Purchase Plan, (viii) 1,060,053 shares of common stock were reserved for issuance pursuant to outstanding restricted shares (shares of common stock subject to forfeiture) and (ix) 1,336,516 shares of common stock were reserved for issuance pursuant to outstanding deferred shares (shares of common stock the issuance of which has been deferred pursuant to Exelon’s Deferred Compensation Plan).

     As of December 31, 2004, Exelon’s capitalization on a consolidated basis was as follows:

5

EXELON CORPORATION
CONDENSED CONSOLIDATED CAPITAL STRUCTURE

(Dollars in Millions)
As of December 31, 2004

Consolidated Capitalization

     Additional information regarding Exelon and its subsidiary companies is set forth in the following documents, each of which has been previously filed with the Commission and is incorporated herein by reference:

(i) Annual Report on Form 10-K of Exelon (Commission File No. 1-16169), ComEd (Commission File No. 1-1839), PECO (Commission File No. 1-1401) and Exelon Generation (Commission File Number No. 333-85496) for the fiscal year ended December 31, 2004, filed with the Commission on February 23, 2005;

(ii) The following Current Reports on Form 8-K of Exelon (Commission File No. 1-16169):

(iii) Annual Report on Form U5S for the fiscal year ended December 31, 2003, filed with the Commission on April 30, 2004; and

(iv) Registration Statement on Form S-4, filed with the Commission on February 10, 2005 (File No. 333-122074).

6

     C. Description of PSEG and Its Subsidiaries.

     1. PSEG, Generally.

     PSEG was incorporated under the laws of the State of New Jersey in 1985 and is an exempt public utility holding company. PSEG, through its subsidiaries, operates in three business segments - Delivery, Generation and Enterprises, as described below. In addition to PSEG’s three business segments, PSEG Services, a subsidiary of PSEG, provides PSEG and its subsidiaries with financial, human resources, legal, information technology, supply management and corporate governance services.

     Delivery – PSEG’s domestic energy delivery business consists of the transmission and distribution of electric energy and gas in New Jersey through PSE&G.

     Generation – PSEG’s generation businesses consist of the owned and contracted for electric generation facilities and energy marketing operations of the PSEG Power subsidiaries and the PSEG Global L.L.C. (“PSEG Global”) subsidiaries. PSEG Power has three principal direct wholly owned subsidiaries: PSEG Nuclear, PSEG Fossil and PSEG ER&T. The PSEG Power generation portfolio consists of approximately 14,607 MW of generation in the Northeast and Midwest. PSEG Global has equity ownership interests in approximately 2,404 MW of generation in North America. All the generation assets in the PSEG system are held by PSEG subsidiaries with EWG or FUCO status under the Act or qualifying facility (“QF”) status under the Public Utility Regulatory Policies Act of 1978, as amended (“PURPA”).

     Enterprises – PSEG’s enterprise businesses consist primarily of (1) investments in energy-related financial transactions, leveraged leases, operating leases, leveraged buyout funds, marketable securities and a demand-side management business and (2) investments in international generation and delivery businesses qualified as EWGs and foreign utility companies through PSEG Resources L.L.C. (“PSEG Resources”) and through PSEG Global.

     2. The PSEG Utility Subsidiary.

     PSE&G is a public utility company within the meaning of the Act and is the only utility subsidiary of PSEG. PSEG directly owns all of the issued and outstanding common stock of PSE&G.

     PSE&G is an electric and gas utility company engaged principally in the transmission and distribution of electric energy and gas in New Jersey. PSE&G is subject to extensive regulation by the New Jersey Board of Public Utilities (“NJBPU”) as to electric and gas rates, the issuance of securities and certain other aspects of PSE&G’s operations. PSE&G is also subject to regulation by the FERC as to electric transmission rates and certain other aspects of its business.

     PSE&G’s retail service territory covers a corridor of approximately 2,600 square miles running diagonally across New Jersey from Bergen County in the northeast to an area below the city of Camden in the southwest with a population of approximately 5.5 million. PSE&G provides service to approximately 2.0 million electric customers and approximately 1.6 million gas customers.

     PSE&G does not own or operate any electric generation facilities. PSE&G, pursuant to an order of the NJBPU issued under the provisions of the New Jersey Electric Discount and Energy Competition Act (“EDECA”), transferred all of its electric generation facilities, plant, equipment and wholesale power trading contracts to its affiliate PSEG ER&T in August 2000. Also, pursuant to an NJBPU order, PSE&G transferred its gas supply business, including its inventories and supply contracts, to a subsidiary of PSEG Power in May 2002. PSE&G continues to own and operate its electric transmission and electric and gas distribution business. PSE&G has transferred operational control over its electric transmission facilities to PJM.

     All electric and gas customers in New Jersey have the ability to choose an electric energy and/or gas supplier. For those retail electric customers located in New Jersey who do not choose a competitive

7

electric supplier, New Jersey’s Electric Distribution Companies (“EDCs”), including PSE&G, provide basic generation service (“BGS”) or provider of last resort service (“POLR”). The EDCs satisfy their BGS obligations through a competitive state-wide annual auction. PSE&G’s affiliate PSEG ER&T, has historically been a successful participant in these auctions and serves several EDCs including PSE&G.

     For those retail gas customers located in New Jersey who do not choose a competitive natural gas supplier, New Jersey’s gas distribution companies, including PSE&G, provide basic gas supply service (“BGSS”) or POLR. PSE&G has entered into a full requirements contract through 2007 with PSEG ER&T to meet the supply requirements of PSE&G’s gas customers. ¹¹ PSEG ER&T charges PSE&G for the gas commodity costs, which PSE&G recovers from its customers. Any difference between rates charged by PSEG ER&T under the BGSS contract and rates charged to PSE&G’s customers are deferred and collected or refunded through future adjustments in retail rates.

     PSE&G’s natural gas facilities consist entirely of local gas distribution facilities in the State of New Jersey and neither PSE&G nor any other PSEG company owns any interstate natural gas facilities subject to the Natural Gas Act.

          3. Direct Non-Utility Subsidiaries of PSEG.

     PSEG has three direct wholly owned non-utility subsidiaries, PSEG Power, PSEG Holdings and PSEG Services:

     PSEG Power - PSEG Power has three principal direct wholly owned subsidiaries: PSEG Nuclear, which owns and operates nuclear generating stations; PSEG Fossil, which develops, owns and operates domestic fossil generating stations and other non-nuclear generating stations; and PSEG ER&T, which markets the capacity and production of PSEG Fossil’s and PSEG Nuclear’s stations, manages the commodity price risks and market risks related to generation and markets electricity, capacity, ancillary services and natural gas products on a wholesale basis. PSEG Power also provides specialized maintenance, repair and plant engineering services on energy-related electro-mechanical equipment to its affiliates.

     PSEG Nuclear is an EWG and has an ownership interest in five nuclear generating units and operates three of them: the Salem Nuclear Generating Station, Units 1 and 2, located in New Jersey, each owned 57.41% by PSEG Nuclear and 42.59% by Exelon Generation; and the Hope Creek Nuclear Generating Station, located in New Jersey, which is 100% owned by PSEG Nuclear. Exelon Generation operates the Peach Bottom Atomic Power Station Units 2 and 3, located in Pennsylvania, each of which is 50% owned by PSEG Nuclear and 50% by Exelon Generation. PSEG Nuclear is subject to regulation by the FERC as to its wholesale electric sales and certain other aspects of its business. All of PSEG Nuclear’s generation assets are located in PJM. As explained below, it is contemplated that PSEG Nuclear will be merged into Exelon Generation.

     PSEG Fossil is an EWG and has direct interests in 12 generating stations in New Jersey and two in Pennsylvania. PSEG Fossil, together with Jersey Central Power and Light Company, is a co-licensee of the Yards Creek Pumped Storage Project, which has a FERC hydroelectric license (Project 2309). All of PSEG Fossil’s directly owned generating assets are located in PJM. PSEG Fossil has certain subsidiaries, that are also EWGs, that own generating stations in Connecticut, New York, Indiana and Ohio. PSEG Fossil is subject to regulation by the FERC as to its wholesale electric sales and certain other aspects of its business. As explained below, it is contemplated that PSEG Fossil will be merged into Exelon Generation and the subsidiaries owned by PSEG Fossil will be retained as direct subsidiaries of Exelon Generation.

8

     PSEG ER&T conducts energy trading operations and does not own any utility assets. PSEG ER&T is subject to regulation by the FERC as to its wholesale electric sales and certain other aspects of its business. As explained below, it is contemplated that PSEG ER&T will be merged into Exelon Generation.

     PSEG Holdings - PSEG Holdings has two principal subsidiaries: PSEG Resources, which invests primarily in energy-related, financial transactions, and PSEG Global, which invests in international generation and delivery businesses qualified as EWGs and FUCOs and domestic generation qualified as EWGs and QFs. ¹²

     PSEG Resources has investments in energy-related financial transactions and assets including leveraged leases, operating leases, leveraged buyout funds, limited partnerships and marketable securities. PSEG Resources also engages in demand side management services in New Jersey through its subsidiaries.

     PSEG Global, through various subsidiaries qualified as FUCOs and EWGs, has investments in electric generation, transmission and distribution facilities in selected international markets and through various subsidiaries qualified as EWGS and QFs, has investments in electric generation in selected domestic markets. PSEG Global’s domestic generation assets are located in California, Pennsylvania, Texas, New Hampshire and Hawaii.

     PSEG Services is a non-utility service company. As explained below, it is contemplated that PSEG Services will sell all of its assets to Exelon BSC, change its name, and remain as a subsidiary.

          4. Capitalization of PSEG.

PUBLIC SERVICE ENTERPRISE GROUP INCORPORATED
CONDENSED CONSOLIDATED CAPITAL STRUCTURE

(Dollars in Millions)
As of December 31, 2004

Consolidated Capitalization