Filed by NSTAR Pursuant to Rule 425

Under the Securities Act of 1933

And Deemed Filed Pursuant to Rule 14a-12

Under the Securities Exchange Act of 1934

Subject Company: NSTAR

Commission File No.: 333-170754

Overview

of

the

Announced

NU/NSTAR

Merger

December 6, 2010

2

Safe Harbor

Information Concerning Forward-Looking Statements

In

addition

to

historical

information,

this

filing

may

contain

a

number

of

“forward-looking

statements”

as

defined

in

the

Private

Securities

Litigation

Reform

Act

of

1995.

Words

such

as

anticipate,

expect,

project,

intend,

plan,

believe,

and

words

and

terms

of

similar

substance

used

in

connection

with

any

discussion

of

future

plans,

actions,

or

events

identify

forward-looking

statements.

Forward-looking

statements

relating

to

the

proposed

merger

include,

but

are

not

limited

to:

statements

about

the

benefits

of

the

proposed

merger

involving

NSTAR

and

Northeast

Utilities,

including

future

financial

and

operating

results;

NSTAR’s

and

Northeast

Utilities'

plans,

objectives,

expectations

and

intentions; the expected timing of completion of the transaction; and other statements relating to the merger that are not historical facts.

Forward-looking statements involve estimates, expectations and projections and, as a result, are subject to risks and uncertainties. There

can be no assurance that actual results will not materially differ from expectations. Important factors could cause actual results to differ

materially from those indicated by such forward-looking statements. With respect to the proposed merger, these factors include, but are not

limited

to:

risks

and

uncertainties

relating

to

the

ability

to

obtain

the

requisite

NSTAR

and

Northeast

Utilities

shareholder

approvals;

the

risk

that

NSTAR

or

Northeast

Utilities

may

be

unable

to

obtain

governmental

and

regulatory

approvals

required

for

the

merger,

or

required

governmental and regulatory approvals may delay the merger or result in the imposition of conditions that could reduce the anticipated

benefits from the merger or cause the parties to abandon the merger; the risk that a condition to closing of the merger may not be satisfied;

the length of time necessary to consummate the proposed merger; the risk that the businesses will not be integrated successfully; the risk

that the cost savings and any other synergies from the transaction may not be fully realized or may take longer to realize than expected;

disruption from the transaction making it more difficult to maintain relationships with customers, employees or suppliers; the diversion of

management time on merger-related issues; the effect of future regulatory or legislative actions on the companies; and the risk that the

credit

ratings

of

the

combined

company

or

its

subsidiaries

may

be

different

from

what

the

companies

expect.

These

risks,

as

well

as

other

risks associated with the merger, are more fully discussed in the joint proxy statement/prospectus that is included in the Registration

Statement on Form S-4 (Registration No. 333-170754) that was filed by Northeast Utilities with the SEC in connection with the merger.

Additional

risks

and

uncertainties

are

identified

and

discussed

in

NSTAR’s

and

Northeast

Utilities’

reports

filed

with

the

SEC

and

available

at

the

SEC’s

website

at

www.sec.gov.

Forward-looking

statements

included

in

this

release

speak

only

as

of

the

date

of

this

release.

Neither

NSTAR nor Northeast Utilities undertakes any obligation to update its forward-looking statements to reflect events or circumstances after

the date of this release.

3

Agenda

Rationale and Benefits of Merger

Overview of NSTAR

Impacts on CL&P and Yankee Gas

4

A

Compelling

Combination

–

Creates

Largest

Utility

Company in New England

Significant transmission investment

opportunities combined with balance sheet

strength provides for substantial growth

potential

Larger, more diverse and better positioned

to support economic growth and

renewables in New England

Accretive to earnings in Year 1 and

provides enhanced total shareholder return

proposition

Enhances service quality capabilities to the

largest customer base in New England

Highly experienced and complementary

leadership team with proven track record

NSTAR Electric Service Area

NSTAR Gas Service Area

Northeast Utilities Electric Service Area

Northeast Utilities Gas Service Area

ME

NY

VT

NH

M

A

RI

Combined Service Territory

5

A New England Based Utility Holding Company

Supporting the Regional Economy

Combined Statistics

2009 Revenue ($bn)

$8.5

Regulated Utilities

6

Regulated States

3

Electric Customers

3,000,000

Gas Customers

500,000

Electric Transmission (Miles)

4,500

Electric Distribution (Miles)

72,000

Gas Distribution (Miles)

6,300

Generation (MW)

1,200

Total Rate Base ($bn)

$10.8

Employees

9,300

$10.8

$9.5

$8.0

$7.0

$6.9

$6.8

$6.6

$5.4

$5.2

$4.1

$4.1

$31.6

SO

XEL

Pro

Forma

NU

DTE

WEC

AEE

CNP

CEG

NU

SCG

TEG

NST

#16

#21

#1

#29

3.1

3.0

2.7

2.4

2.4

2.1

2.1

2.1

1.9

1.8

1.1

1.1

0.7

5.4

EXC

PGN

Pro

Forma

NU

ETR

AEE

D

CNP

DTE

PEG

NU

POM

PNW

NST

SCG

#13

#19

#1

#26

___________________________

Source: FactSet, company filings.

1.  US utility rankings as of 10/15/10, based on companies in the S&P 500 Utilities Index excluding IPPs and Gas LDCs.

Ranking

by

Market

Capitalization

($

in

billions)

Ranking

by

Electric

Customers

(in

millions)

(1)

(1)

6

Specific Benefits to NU

A projected ~ 20% dividend increase

Cash flow increase to eliminate equity issuance for foreseeable

future

Likely credit upgrades and reduction in debt issuance leading to

lower long-term, short-term interest costs

Increased market liquidity

Enhanced opportunities to reduce costs over time

Ability to achieve higher earnings growth rate

7

Enhanced Credit Quality

Strong balance sheet and cash flows position NU to fund rate

base growth program principally through internally generated

funds

Combined company and operating subsidiaries will have an

enhanced credit profile

Highest quality business profile

Highly diversified earnings and cash flow

100% stock transaction –

no new debt issued for merger

No long-term debt triggers

8

Benefits to NSTAR

Enhanced earnings and dividend growth outlook

Ability to apply strong balance sheet and cash flow to attractive

transmission investment opportunities

Larger utility footprint provides access to projects and opportunities

not available today

More diverse and better balanced earnings profile

Compelling total return opportunity

9

Key Merger Terms

Timing / Approvals:

Expected

to

close

within

9

–

12

months

Shareholders, federal, and state

Headquarters:

Dual –

Hartford and Boston

Company Name:

Northeast Utilities

Consideration:

100% NU shares

Exchange Ratio:

1.312 shares of NU per NSTAR share

Pro Forma Ownership:

56% NU shareholders

44% NSTAR shareholders

Pro Forma Dividend:

Following close, dividend increase for NU shareholders to NSTAR

level

Dividend parity for NSTAR shareholders

Governance:

Chuck Shivery to be non-executive Chairman

Tom May to be President and CEO

14 Board members

7 nominated by Northeast Utilities including Chuck Shivery

7 nominated by NSTAR including Tom May

Balanced Terms and Governance

10

Post Merger High Level Company Organization Chart

Northeast Utilities

Connecticut Light

& Power

Yankee Energy

Systems, Inc.

(Holding Company)

NU Enterprises, Inc

Public Service

Company of New

Hampshire

Western

Massachusetts

Electric Company

NSTAR LLC

(Holding Company)

NSTAR Companies

(NSTAR Electric,

NSTAR Gas, etc.)

Other NU Companies

(NUSCO, Rocky

River Realty, etc.)

Yankee Gas

Services Company

11

Executive Management Organization

Tom May

President & Chief

Executive Officer

Greg Butler

General Counsel

David McHale

Chief Administrative

Officer

Lee Olivier

Chief Operating

Officer

Christine Carmody

Human Resources

Jim Judge

Chief Financial Officer

Joe Nolan

Corporate Relations

Chuck Shivery

Non-Executive

Chairman

12

Building A Larger, More Diverse and Better Positioned

Regulated Utility Business

FERC

31%

CT

26%

NH

11%

MA

32%

Rate Base By State / Federal

Electric

Generation

4%

Electric

Distribution

54%

Gas

Distribution

11%

Electric

Transmission

31%

Rate Base By Business

Combined 2009 Rate Base: $10.8 billion

13

Southwest Connecticut Reliability:

Projects Complete

1

Connecticut Borders (MA, RI):

NEEWS Projects Under Way

3

5

Excellent Transmission Opportunities into Largest

New England Load Centers

Hydro-Québec-

HVDC

4

HVDC Line between Québec and New

Hampshire

Potential Wind Sites

Southeastern Massachusetts (MA):

Cape Cod Line

2

Load Center Populations

(1)

Greater Boston:

4,600,000

Hartford:

1,200,000

Fairfield County:

900,000

1.

.Source: IHS Global Insight Winter 2009 – 2010, US Markets: State Economies, U.S. Census Bureau 2009 estimates.

13

Renewables & Clean Energy (ME/NH/VT):

Projects in Development/

High Wind potential areas

14

Regulatory Timeline

Oct 2010

Closing Expected in 9 –

12 months

Q4 2010

Q1 2011

Q2 2011

Q3 2011

Merger Announced

Commence

Regulatory Filings

File Joint Proxy

Statement/Prospectus

Regulatory Processes

FERC, SEC, NRC, DOJ,

MDPU, FCC, Maine PUC

Northeast Utilities and

NSTAR Shareholder

Meetings

Develop Transition Implementation Plans

Receive Regulatory

Approvals

Close Merger

15

NSTAR –

A Track Record of Strong Performance

•

High levels of customer service and

reliability

•

Constructive regulatory outcomes

•

Solid, consistent financial results

•

Strong credit profile and positive cash flow

NSTAR –

Key Facts and Figures

NSTAR is the largest Massachusetts-based

investor-owned electric and gas utility

NSTAR transmits and delivers electricity and

gas to 1.1 million electric customers in 81

communities and approximately 300,000 gas

customers in 51 communities

Residential customers comprise 87% of the

total electric customers and 90% of the total

gas customers

For the nine months ended September 30,

2010, NSTAR derived 86% of its operating

revenues from electric operations and 14%

from gas operations

NSTAR employs more than 3,000 people

Service Territory

MA

NSTAR Electric Service Area

NSTAR Gas Service Area

16

17

NSTAR Electric

Provides distribution and transmission electricity service to 1.1 million

customers over an area of 1,702 square miles

Approximately 35,000 miles of distribution lines with 37% being under

ground, and 951 miles of transmission lines

Created January 1, 2007 through the merger of Commonwealth Electric

Company, Cambridge Electric Light Company, and Boston Edison

Company

Currently

operating

under

a

2007

–

2012

distribution

rate

settlement

that establishes annual inflation-adjusted distribution rates that are

generally offset by an equal reduction in transition rates (stranded cost

charges)

Distribution rate base at 12/31/09 of $2.5 billion

Transmission rates set by the FERC as part of ISO-NE regional system

(similar to NU)

18

NSTAR Gas

Distributes natural gas to approximately 300,000 customers over an

area of 1,067 square miles

Like Yankee Gas, the sales and transportation of gas are divided

into

two categories –

firm and interruptible

Supply portfolio consists of natural gas supply contracts, transportation

contracts on interstate pipelines, market area storage and peaking

services

A portion of the gas supply storage is provided by Hopkinton, a wholly-

owned subsidiary of NSTAR, with facilities consisting of LNG

liquefaction and vaporization, and above-ground storage tanks

Last rate proceeding was a settlement in 2005

Commercial, industrial, and residential customers can choose their

supplier of natural gas

Rate base at 12/31/09 of $500 million

19

A Long History of Negotiated, Multi-Year Distribution

Rate Agreements

•

25

years

of

rate

agreements

–

last

litigated

rate

increase

in

1986

•

Fully reconciling pension & post-retirement mechanism and

recovery of energy supply

•

Current electric seven year rate plan through December 31, 2012

•

10.5% ROE with +/-

2% neutral zone

•

Plan to pursue a new rate agreement effective in 2013

20

History of Disciplined Cost Control

$453

2005

$431

2006

2007

Operations & Maintenance Expense

$447

$ IN MILLIONS

2008

$454

2009

$431

•

Productivity & automation

•

Performance driven

culture

•

Engaged workforce and

constructive union

relations

•

Continuous improvement

philosophy

Key

Drivers

21

Highest Credit Rating in the Industry

NSTAR

A+

FPL Group, Inc.

A

Southern Company

A

Consolidated Edison, Inc.

A-

Dominion Resources, Inc.

A-

DPL Inc.

A-

Duke Energy Corporation

A-

Energy East Corporation

A-

KeySpan Corp.

A-

Niagara Mohawk Power Corporation

A-

Vectren Corporation

A-

ALLETE, Inc.

BBB+

Alliant Energy Corporation

BBB+

Integrys Energy Group, Inc.

BBB+

Kentucky Utilities Company

BBB+

Louisville Gas and Electric Company

BBB+

MDU Resources Group, Inc.

BBB+

MidAmerican Energy Holdings Company

BBB+

OGE Energy Corp.

BBB+

PG&E Corporation

BBB+

Portland General Electric Company

BBB+

Progress Energy, Inc.

BBB+

SCANA Corporation

BBB+

Sempra Energy

BBB+

Wisconsin Energy Corporation

BBB+

Xcel Energy Inc.

BBB+

American Electric Power Company, Inc.

BBB

CenterPoint Energy, Inc.

BBB

Cleco Corporation

BBB

El Paso Electric Company

BBB

Energy Corporation

BBB

Exelon Corporation

BBB

FirstEnergy Corp.

BBB

Great Plains Energy Inc.

BBB

Green Mountain Power Corporation

BBB

Hawaiian Electric Industries, Inc.

BBB

IDACORP, Inc.

BBB

Northeast Utilities

BBB

North Western Corporation

BBB

Pepco Holdings, Inc.

BBB

PPL Corporation

BBB

Public Service Enterprise Group Inc.

BBB

TECO Energy, Inc.

BBB

UIL Holdings Corporation

BBB

Allegheny Energy, Inc.

BBB-

Ameren Corporation

BBB-

Avista Corporation

BBB-

Black Hills Corporation

BBB-

CMS Energy Corporation

BBB-

Constellation Energy Group, Inc.

BBB-

Duquesne Light Company

BBB-

Edison International

BBB-

Empire District Electric Company

BBB-

IPALCO Enterprises, Inc.

BBB-

NiSource Inc.

BBB-

Otter Tail Corporation

BBB-

Pinnacle West Capital Corporation

BBB-

Westar Energy, Inc. Puget Energy, Inc.

BBB-

Puget Energy, Inc.

BB+

NV Energy, Inc.

BB

PNM Resources, Inc.

BB-

Energy Future Holdings Corp.

B-

#1 NSTAR

A+

*As published by EEI

22

Earnings and Dividend Growth

$2.22

$1.93

$2.07

2006

2007

2008

2009

$2.37

$2.45 -

$2.60

2010

Guidance

$1.21

$1.30

$1.40

2006

2007

$1.50

2008

2009

2010

$1.60

Earnings Growth of 7% Outperforms

Industry…19 Consecutive Years of

Operating Earnings Growth

Consistent, Above Average Dividend

Growth…12 Consecutive Years of

Increase

23

Impact on CL&P and Yankee Gas

No changes to the tariff rates or services of CL&P or Yankee Gas

(or

other NU affiliates) are planned or contemplated as a condition of the

merger

There is no consolidation of NSTAR Electric, NSTAR Gas, CL&P,

and/or Yankee Gas (or other NU affiliates) that would result from the

merger

The merger will not result in a change of control of CL&P or Yankee

Gas (or other NU affiliates) and they will continue to be first-tier

subsidiaries of NU

The merger will strengthen the financial integrity and investment

capability of NU; a corollary effect will be the enhancement of CL&P’s

and Yankee Gas’

capability to maintain reliable and cost-effective

delivery systems

Over time, the integration of NSTAR and NU is anticipated to produce

net savings in costs that will be passed on to customers through

reduced costs of service

24

Creates New England’s premier energy provider

More diverse, stable and higher earnings growth profile than could

be achieved standalone

Highly experienced management teams with proven track records

of success

Combined company will have one of the most attractive total

return profiles in the industry

Summary

25

Appendix

26

NSTAR Electric

Comparison of typical bills*

Boston

Cambridge

Commonwealth

CL&P

Edison

Electric

Electric

Generation

$82.88

$59.85

$59.85

$59.85

Transmission

$13.39

$11.15

$13.70

$11.80

Delivery

$38.34

$48.10

$42.26

$48.96

Other

$7.98

$5.14

-$3.07

$11.90

TOTAL BILL

$142.59

$124.24

$112.74

$132.51

Non-Generation

$59.71

$64.39

$52.89

$72.66

Residential (Based on 750 kWh per Month)

Boston

Cambridge

Commonwealth

CL&P

Edison

Electric

Electric

Generation

$1,172

$853

$853

$798

Transmission

$182

$372

$204

$160

Delivery

$464

$865

$436

$419

Other

$142

$69

$1

$159

TOTAL BILL

$1,960

$2,159

$1,494

$1,536

Non-Generation

$788

$1,306

$641

$738

Commercial (Based on 10,000 kWh per Month & 40 kW (33% Load Factor))

*As published by EEI –

Typical Bills, Summer 2010

27

NSTAR Electric

Comparison of typical bills*

Boston

Cambridge

Commonwealth

CL&P

Edison

Electric

Electric

Generation

$25,582

$28,424

$28,424

$28,236

Transmission

$5,368

$6,220

$4,987

$6,316

Delivery

$7,404

$17,829

$7,285

$8,975

Other

$4,208

$3,262

-$611

$6,810

TOTAL BILL

$42,562

$55,735

$40,085

$50,337

Non-Generation

$16,980

$27,311

$11,661

$22,101

Industrial (Based on 400,000 kWh per Month & 1,000 kW (54% Load Factor))

*As published by EEI –

Typical Bills, Summer 2010

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. In connection with the proposed merger between Northeast Utilities and NSTAR, on November 22, 2010, Northeast Utilities filed with the SEC a Registration Statement on Form S-4 (Registration No. 333-170754) that includes a preliminary joint proxy statement of Northeast Utilities and NSTAR that also constitutes a preliminary prospectus of Northeast Utilities. These materials are not yet final and may be amended. Northeast Utilities and NSTAR will mail the final joint proxy statement/prospectus to their respective shareholders. Northeast Utilities and NSTAR urge investors and shareholders to read the joint proxy statement/prospectus regarding the proposed merger when it becomes available, as well as other documents filed with the SEC, because they will contain important information. You may obtain copies of all documents filed with the SEC regarding this proposed transaction, free of charge, at the SEC’s website (www.sec.gov). You may also obtain these documents, free of charge, from Northeast Utilities’ website (www.nu.com) under the tab “Investors” and then under the heading “Financial/SEC Reports.” You may also obtain these documents, free of charge, from NSTAR’s website (www.nstar.com) under the tab “Investor Relations.”

Participants in the Merger Solicitation

Northeast Utilities, NSTAR and their respective trustees, executive officers and certain other members of management and employees may be soliciting proxies from Northeast Utilities and NSTAR shareholders in favor of the merger and related matters. Information regarding the persons who may, under the rules of the SEC, be deemed participants in the solicitation of Northeast Utilities and NSTAR shareholders in connection with the proposed merger will be set forth in the joint proxy statement/prospectus when it is filed with the SEC. You can find information about NSTAR’s executive officers and trustees in its definitive proxy statement filed with the SEC on March 12, 2010. You can find information about Northeast Utilities’ executive officers and trustees in its definitive proxy statement filed with the SEC on April 1, 2010. Additional information about Northeast Utilities’ executive officers and trustees and NSTAR’s executive officers and trustees can be found in the above-referenced Registration Statement on Form S-4 when it becomes available. You can obtain free copies of these documents from NSTAR and Northeast Utilities using the website information above.