Edgar Filing: Williams Partners L.P.

425

Filed by The Williams Companies, Inc.

Pursuant to Rule 425 under the Securities Act of 1933

Subject Company: Williams Partners L.P.

Commission File No.: 001-32599

The following is a slide presentation made publicly available by The Williams Companies, Inc., Williams Partners L.P., and Access Midstream Partners, L.P. in connection with the announcement of financial results for the quarter ended September 30, 2014.

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Williams, Williams Partners and

Access Midstream Partners Third Quarter 2014 Earnings

October 30, 2014

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Presentation overview

WPZ 3Q results in line with our expectations:

Lower results vs. normal, expanded operations due to Geismar outage (lost opportunity of ~$200MM)

Seasonally higher maintenance capital, as expected

Strong 3Q for ACMP on record volumes

WPZ expecting nearly $1 billion in annual cash flow from projects nearing in-service:

Expect improved results in 4Q and 2015 as we place major projects into service in November and December

Gulfstar One (November), expanded Geismar (November), Keathley Canyon Connector (December)

Continuing string of major Transco expansion projects, prospects

WPZ/ACMP merger agreement finalized; creating industry leading MLP

Expect to close early ’15targeting January

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WPZ 3Q DCF impacted by Geismar downtime;

3Q ACMP DCF shows strong 42% growth

WMB expects $521 million in MLP cash distributions

WPZ 3Q vs. prior year

Distributable Cash Flow $367 million

Fee-based revenues up $35 million

to $756 million

108% higher distributions from equity

investees, up $37 million to $71 million

Blue Racer, LMM, Discovery all higher

Adjusted segment profit + DD&A $575

million

3Q’14 includes no contribution from

Geismar (lost opportunity of ~$200MM)

WMB 3Q vs. prior year

Adjusted Segment Profit + DD&A

36% higher, up $221 million to $838 million

Includes effect of consolidating ACMP beginning 3Q’14

MLP Cash distributions in November:

Williams Partners, $438 million

ACMP, $83 million, including higher ownership interest

WMB NGL & Petchem Services

Segment only includes development projects expected to be dropped down to WPZ in late 2014 or early 2015

ACMP 3Q vs. prior year

42% higher Adjusted Distributable Cash Flow, up $72 million to $244 million

20% higher fee-based revenues, up $53 million to $314 million

Adjusted Segment Profit + DD&A, Distributable Cash Flow and Adjusted Distributable Cash Flow (DCF) are non-GAAP measures. Reconciliations to the most relevant measures included in GAAP are provided in this presentation and on ACMP’s website.

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ACMP: continued record volumes and strong financial performance

3Q results vs. prior year

Adjusted EBITDA of $319 million, up 40%

Adjusted DCF of $244 million, up 42%

Adjusted cash distribution coverage of 1.67x

Distribution increase to $0.615, up 15%

3Q operational highlights

Over 6 Bcf/dgross volume recordSeptember 2014

CHK/SWN transaction strengthens CHK credit and reduces CHK concentration; SWN becomes a growth-motivated, new ACMP customer with strong credit profile

UEO Leesville Processing Planttrain one online EOY 2014 and train two online EOY 2015

Niobrara Bucking Horse Processing Plantonline EOY 2014

3Q gathering volumes and capital expenditures

Total net volume of 4.1 Bcf/d, up 9%; 3Q capex of $272 million and YTD capex of $911 million

Marcellus—1.2 Bcf/d, up 12%; 3Q capex of $56 million and YTD capex of $143 million

Eagle Ford—348 MMcf/d, up 18%; 3Q capex of $33 million and YTD capex of $157 million

Utica—418 MMcf/d, up ~200%; 3Q capex of $88 million and YTD capex of $362 million

Adjusted EBITDA, Adjusted Distributable Cash Flow (DCF) and Adjusted Cash Distribution Coverage ratio are non-GAAP measures. Reconciliations to the most relevant measures included in GAAP are provided on ACMP’s website.

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WPZ: Large-scale, value-creating projects ready to contribute; many more to come

Near-Term Growth Drivers

Expecting nearly $1 billion of annual cash flows coming from projects starting up in 4Q

- Gulfstar One

- Geismar expansion

- Keathley Canyon

Connector

Recent Milestones

Geismar restart

- All construction complete

- Startup procedures underway

- Expect ethylene sales at expanded production in November

Several new OVM projects placed in service

Laurel Mountain Midstream interest now 69%

Gulfstar One turned over to producer for first-oil

Keathley Canyon mechanically complete; expect 4Q first production

Constitution Pipeline progress; FERC issues final EIS

Transco’s industry-leading market and supply growth

- Two major new open seasons

- South LA methanol project

- Rockaway Lateral project construction progressing

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Nearly $30 Billion in WPZ/ACMP committed plus potential capital projects 2014-19

TARGET IN-SERVICE DATES FOR VISIBLE GROWTH PROJECTS

*WMB projects expected to be dropped down to WPZ in late 2014 to early 2015

2014 2015 2016 2017 2017+

NE: Frac II Rockaway Gunflint Atlantic Sunrise Northeast G&P

NE: ethane line Lateral Northeast G&P Dalton Lateral Sabal Trail ownership option

& de-ethanizer Constitution

NE: Other Pipeline1 Plant Parachute Expansion Phase Hillabee 1 expansions Transconumerous other

facilities Leidy SE Northeast G&P Gulfstar FPS and pipelines

Gulfstar One Virginia U.S., PEMEX

Southside Gulf Trace

NE: Oak Grove Gulf of Mexicoother

Garden State

TXP I Kodiak oil-driven services

Keathley Northeast G&P Pacific Connector and other

Canyon NWP projects

Mobile Bay

Connector South III Canadian PDH 1&2*

Geismar

Expansion CNRL Offgas Syncrude Offgas Processing*

Processing* Geismar 2*

Gulf Coast

Petchem

Services* In progress

Potential/under negotiation

Plus $4 billion2 ACMP Growth Capex

1. Constitution Pipeline expected in-service date range is late 2015 to 2016. 2. ACMP growth capex range is $3.675 billion to $4.075 billion.

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Transco’s proposed Appalachian Connector project creates direct access to major Transco system markets

Oak Grove

Clarington Fort Beeler

Natrium River Road

Transco’s Proposed

Strong response to Appalachian Connector

Project

open season;

negotiating precedent

agreements 165

155

Capacity: ~2 Bcf/d

Target in-service:

Late 2018 140

125

85 100

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ACMP/WPZ merger will create leading, large-cap natural gas MLP

Expected 2015 adjusted EBITDA of approximately $5 billion

Expected

Expect $3.65 per unit distribution from merged MLP in 2015, up 50% and 30%, respectively, from

Benefits ACMP’s 2Q 2014 distribution and 2015 distribution guidance1

Best-in-class distribution growth rate of 10-12% through 2017 with strong distribution coverage ratio

Financial estimated to be approximately at or above 1.1x or an aggregate of $1.1 billion of excess cash flow

through 2017

Expected strong investment-grade credit ratings with limited equity needs in current business plan

Expected Creates one of the largest MLPs with leading positions across the three key components of the

midstream sector:

Benefits Natural Gas Pipelines: Transco, Northwest and Gulfstream represent the nation’s premier interstate pipeline system

Natural Gas Gathering and Processing: Large-scale positions in growing natural gas supply areas in major shale

and unconventional producing areas

NGL and Petrochemical Services: Unique downstream presence on Gulf Coast and in western Canada provides

Commercial differentiated long-term growth

and Combines the stability and growth of Access Midstream Partners’ current contract portfolio with

Operational Williams Partners’ significant long-term growth opportunities and development expertise

Opportunity to further enhance and streamline operations, business-development, commercial and

support capabilities

Aligns WPZ and ACMP unitholders

Expected to increase efficiency in capital allocation to growth opportunities

1Assumes merger is completed before record date of related cash distributions and subject to board approval.

Cash distribution coverage ratio and adjusted EBITDA are non-GAAP measures. Reconciliations to the most relevant measures included in GAAP are provided in this presentation.

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Significant valuation re-rating opportunity still ahead

2014-2016 DISTRIBUTION CAGR

Current Yield

10.0% Median large-cap, diversified coverage ratio is 1.1x

Merged MLP expected to be at or above 1.1x through 2017

8.0%

WPZ Implied ACMP/WPZ at 3.6%

EEP yield ~$94

6.0% ETP(based on 85 cent distribution for 1Q’15)

OKS

PAA

SEP ACMP2

4.0% EPD

2.0%

Pro Forma ACMP / WPZ

0.0% ‘14’16

0.0% 5.0% 10.0% 15.0% Distribution CAGR

Source: Company filings and FactSet as of 10/27/2014

Notes: 1. Based on Wall Street research consensus as of 10/20/2014; 2. ACMP is not included in the regression line; 3. Peer group includes large cap diversified midstream MLPs

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Williams well positioned to participate in once-in-a-generation industry supercycle

WMB now one of the largest publicly traded GP holding companies with control of both WPZ and ACMP

ACMP/WPZ merger will create leading natural gas MLP

Right long-term strategy at the right time

Ideally positioned assets, sustainable competitive positions

Hard-wired focus on safe, reliable operations and project execution

Nearly $30 billion of potential growthdisciplined capital allocation

Strong leadership in place to capture the value opportunity

All the right ingredients to deliver sustained value growth

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Forward Looking Statements and Non-GAAP Reconciliations

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Important information

In connection with the proposed merger of ACMP and WPZ, ACMP will file with the SEC a Registration Statement on Form S-4 that will include a consent statement of WPZ that will also constitute a prospectus of ACMP. WPZ will mail the consent statement/prospectus to the holders of WPZ units. Investors are urged to read the consent statement/prospectus and other relevant documents filed with the SEC regarding the proposed transaction when they become available, because they will contain important information. The consent statement/prospectus and other documents that will be filed by ACMP and WPZ with the SEC will be available free of charge at the SEC’s website, www.sec.gov, or by directing a request when such a filing is made either to Access Midstream Partners L.P., 525 Central Park Drive, Oklahoma City, Oklahoma 73105, Attention: Investor Relations, or to Williams Partners L.P., One Williams Center, Tulsa, Oklahoma 74172, Attention: Investor Relations.

ACMP, WPZ and certain of their directors and executive officers may be deemed to be “participants” (as defined in Schedule 14A under the Exchange Act) in respect of the proposed transaction. Information about ACMP’s directors and executive officers is available in ACMP’s annual report on Form 10-K for the fiscal year ended December 31, 2014, as amended, initially filed with the SEC on February 21, 2014.

Information about WPZ’s directors and executive officers is available in WPZ’s annual report on Form 10-K for the fiscal year ended December 31, 2013 filed with the SEC on February 26, 2014. Other information regarding the participants and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the consent statement/prospectus and other relevant materials to be filed with the SEC regarding the transaction. Investors should read the consent statement/prospectus carefully when it becomes available before making any voting or investment decisions. You may obtain free copies of these documents from WPZ or ACMP using the sources indicated above.

This document shall not constitute an offer to sell or the solicitation of an offer to buy any securities, 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. No offering of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the U.S. Securities Act of 1933, as amended.

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Forward Looking Statements

The reports, filings, and other public announcements of The Williams Companies, Inc. (Williams) and Williams Partners L.P. (WPZ) may contain or incorporate by reference statements that do not directly or exclusively relate to historical facts. Such statements are “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. We make these forward-looking statements in reliance on the safe harbor protections provided under the Private Securities Litigation Reform Act of 1995. You typically can identify forward-looking statements by various forms of words such as “anticipates,” “believes,” “seeks,” “could,” “may,” “should,” “continues,” “estimates,” “expects,” “forecasts,” “intends,” “might,” “proposed,” “goals,” “objectives,” “targets,” “planned,” “potential,” “projects,” “scheduled,” “will,” “assumes,” “guidance,” “outlook,” “in service date” or other similar expressions. These forward-looking statements are based on management’s beliefs and assumptions and on information currently available to management and include, among others, statements regarding:

The levels of dividends to Williams stockholders;

Expected levels of cash distributions by Access Midstream Partners, L.P. (“ACMP”) and WPZ with respect to general partner interests, incentive distribution rights, and limited partner interests;

The closing, expected timing and benefits of the proposed merger of ACMP and WPZ;

The expected timing of the drop-down of Williams’ remaining NGL & Petchem Services assets and projects;

Amounts and nature of future capital expenditures;

Expansion and growth of our business and operations;

Financial condition and liquidity;

Business strategy;

Cash flow from operations or results of operations;

Seasonality of certain business components;

Natural gas, natural gas liquids, and olefins prices, supply, and demand;

Demand for our service.

Forward-looking statements are based on numerous assumptions, uncertainties and risks that could cause future events or results to be materially different from those stated or implied in this presentation. Many of the factors that will determine these results are beyond our ability to control or predict. Specific factors that could cause actual results to differ from results contemplated by the forward-looking statements include, among others, the following:

Whether WPZ, ACMP, or the merged partnership will produce sufficient cash flows to provide the level of cash distributions we expect;

Whether Williams is able to pay current and expected levels of dividends;

Availability of supplies, market demand, and volatility of commodity prices;

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Forward Looking Statements (cont’d)

Inflation, interest rates, and fluctuation in foreign exchange rates and general economic conditions (including future disruptions and volatility in the global credit markets and the impact of these events on customers and suppliers);

The strength and financial resources of our competitors and the effects of competition;

Whether we are able to successfully identify, evaluate and execute investment opportunities;

Our ability to acquire new businesses and assets and successfully integrate those operations and assets, including ACMP’s business, into our existing businesses as well as successfully expand our facilities;

Development of alternative energy sources;

The impact of operational and developmental hazards and unforeseen interruptions;

The ability to restart the Geismar plant and recover expected insurance proceeds;

Costs of, changes in, or the results of laws, government regulations (including safety and environmental regulations), environmental liabilities, litigation, and rate proceedings;

Williams’ costs and funding obligations for defined benefit pension plans and other postretirement benefit plans sponsored by its affiliates;

WPZ’s allocated costs for defined benefit pension plans and other postretirement benefit plans sponsored by its affiliates;

Changes in maintenance and construction costs;

Changes in the current geopolitical situation;

Exposure to the credit risk of our customers and counterparties;

ACMP’s dependence on a limited number of customers and vendors;

Risks related to financing, including restrictions stemming from debt agreements, future changes in Williams credit ratings as well as the credit ratings of ACMP, WPZ or the merged partnership as determined by nationally-recognized credit rating agencies and the availability and cost of capital;

The amount of cash distributions from and capital requirements of our investments and joint ventures in which we participate;

Risks associated with weather and natural phenomena, including climate conditions;

Acts of terrorism, including cybersecurity threats and related disruptions; and

Additional risks described in our filings with the Securities and Exchange Commission (SEC).

Given the uncertainties and risk factors that could cause our actual results to differ materially from those contained in any forward-looking statement, we caution investors not to unduly rely on our forward-looking statements. We disclaim any obligations to and do not intend to update the above list or announce publicly the result of any revisions to any of the forward-looking statements to reflect future events or developments.

In addition to causing our actual results to differ, the factors listed above may cause our intentions to change from those statements of intention set forth in this announcement. Such changes in our intentions may also cause our results to differ. We may change our intentions, at any time and without notice, based upon changes in such factors, our assumptions, or otherwise.

Investors are urged to closely consider the disclosures and risk factors in Williams’ and WPZ’s annual reports on Form 10-K filed with the SEC on Feb. 26, 2014, and each of our quarterly reports on Form 10-Q available from our offices or from our websites at www.williams.com and www.williamslp.com.

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FORWARD-LOOKING STATEMENTS

Certain statements and information in this presentation may constitute forward-looking statements. The words “believe,” “expect,” “anticipate,” “plan,” “intend,” foresee,” “should,”

“would,” “could,” or similar expressions are intended to identify forward-looking statements, which are generally not historical in nature. These forward-looking statements are based on current expectations and beliefs concerning future developments and their potential effect on us. While management believes that these forward-looking statements are reasonable as and when made, there can be no assurance that future developments affecting us will be those that we anticipate. All comments concerning our expectations for future revenues and operating results are based on our forecasts for our existing operations and do not include the potential impact of any future acquisitions. Our forward-looking statements involve significant risks and uncertainties (some of which are beyond our control) and assumptions that could cause actual results to differ materially from our historical experience and our present expectations or projections. Important factors that could cause actual results to differ materially from those in the forward-looking statements include, but are not limited to, those summarized below: dependence on Chesapeake Energy Corporation, Total E&P USA, Inc., Mitsui & Co., Anadarko Petroleum Corporation and Statoil for a majority of our revenues; the impact on our growth strategy and ability to increase cash distributions if producers do not increase the volume of natural gas they provide to our gathering systems; oil and natural gas realized prices; the termination of our gas gathering agreements; the availability, terms and effects of acquisitions; our potential inability to maintain existing distribution amounts or pay the minimum quarterly distribution to our unitholders; the limitations that our level of indebtedness may have on our financial flexibility; our ability to obtain new sources of natural gas, which is dependent on factors largely beyond our control; the availability of capital resources to fund capital expenditures and other contractual obligations, and our ability to access those resources through the debt or equity capital markets; competitive conditions; the unavailability of third-party pipelines interconnected to our gathering systems or the potential that the volumes we gather do not meet the quality requirement of such pipelines; new asset construction may not result in revenue increases and will be subject to regulatory, environmental, political, legal and economic risks; our exposure to direct commodity price risk may increase in the future; our ability to maintain and/or obtain rights to operate our assets on land owned by third parties; hazards and operational risks that may not be fully covered by insurance; our dependence on Exterran Partners, L.P. for a significant portion of our compression capacity; our lack of industry diversification; and legislative or regulatory changes, including changes in environmental regulations, environmental risks, regulations by FERC and liability under federal and state environmental laws and regulations.

Other factors that could cause our actual results to differ from our projected results are described in our 2013 Form 10-K and our other SEC filings. Individuals are cautioned not to place undue reliance on forward-looking statements, which speak only as of the date hereof. We undertake no obligation to publicly update or revise any forward-looking statements after the date they are made, whether as a result of new information, future events or otherwise.

Williams, Williams Partners and Access Midstream Partners Third Quarter 2014 15 Earnings | 10/30/14

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WMB Non-GAAP Disclaimer

This presentation includes certain financial measuresadjusted segment profit, adjusted segment profit + DD&A, adjusted income from continuing operations (“earnings”) and adjusted earnings per sharethat are non-GAAP financial measures as defined under the rules of the Securities and Exchange Commission. Adjusted segment profit, adjusted earnings and adjusted earnings per share measures exclude items of income or loss that the company characterizes as unrepresentative of its ongoing operations and may include assumed business interruption insurance related to the Geismar plant. Management believes these measures provide investors meaningful insight into the company’s results from ongoing operations.

This presentation is accompanied by a reconciliation of these non-GAAP financial measures to their nearest GAAP financial measures. Management uses these financial measures because they are widely accepted financial indicators used by investors to compare a company’s performance. In addition, management believes that these measures provide investors an enhanced perspective of the operating performance of the company and aid investor understanding. Neither adjusted segment profit, adjusted segment profit + DD&A, adjusted earnings nor adjusted earnings per share measures are intended to represent an alternative to segment profit, net income or earnings per share. They should not be considered in isolation or as substitutes for a measure of performance prepared in accordance with United States generally accepted accounting principles.

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WMB Non-GAAP Reconciliations

WMB non-GAAP reconciliation schedule

2013 2014

(Dollars in millions, except per-share amounts) 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr Year 1st Qtr 2nd Qtr 3rd Qtr Year

Income (loss) from continuing operations attributable to The Williams Companies, Inc. available to common

stockholders $ 162 $ 149 $ 143 $(13 ) $ 441 $ 140 $ 99 $ 1,678 $ 1,917

Income (loss) from continuing operations—diluted earnings per common share $ .23 $ .22 $ .20 $(.02 ) $ .64 $ .20 $ .14 $ 2.22 $ 2.68

Adjustments:

Williams Partners

Net loss (recovery) related to Eminence storage facility leak

$ — $(5 ) $ 5 $(2 ) $(2 ) $ — $ — $ — $ —

Share of impairments at equity method investee

— — — 7 7 — — — —

Contingency loss (gain)

(6) — 9 16 19 — — — —

Loss related to Geismar Incident

— 6 4 4 14 — — 5 5

Geismar Incident adjustment for insurance and timing

— —(35 ) 118 83 54 96 — 150

Loss related to compressor station fire — — — — — 6 — — 6

Impairment of certain equipment held for sale — — — — — — 17 — 17

Loss related to Opal incident — — — — — — 6 — 6

Net gain related to partial acreage dedication release — — — — — — —(12 )(12 )

Total Williams Partners adjustments(6) 1(17 ) 143 121 60 119(7 ) 172

Access Midstream Partners

Equity-method investment in ACMP remeasurement gain — — — — — — —(2,522 )(2,522 )

WMB impact of ACMP transaction-related compensation expenses — — — — — — — 24 24

Gain associated with ACMP equity issuance

—(26 ) —(5 )(31 ) —(4 )(1 )(5 )

Acquisition-related expenses — — — — — — 2 13 15

Transition costs — — — — — — — 8 8

Total Access Midstream Partners adjustments

—(26 ) —(5 )(31 ) —(2 )(2,478 )(2,480 )

Williams NGL & Petchem Services

Write-off of abandoned project

— — — 20 20 — — — —

Bluegrass Pipeline project development costs—(100% consolidated) — — — — — 19 — — 19

Bluegrass Pipeline and Moss Lake project development costs (50% equity investment losses) — — — — — 6 1 — 7

Equity investment losses related to Bluegrass Pipeline and Moss Lake write-offs — — — — — 70 — — 70

Total Williams NGL & Petchem Services adjustments — — — 20 20 95 1 — 96

Adjustments included in segment profit (loss)(6 )(25 )(17 ) 158 110 155 118(2,485 )(2,212 )

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WMB Non-GAAP Reconciliations

WMB non-GAAP reconciliation schedule cont’d

2013 2014

(Dollars in millions, except per-share amounts) 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr Year 1st Qtr 2nd Qtr 3rd Qtr Year

Adjustments below segment profit (loss)

Reorganization-related costs 2 — — — 2 — — — —

Transition-related costs — — — — — — — 6 6

Acquisition-related financing expenses—Access Midstream Partners — — — — — — 9 — 9

Interest income on receivable from sale of Venezuela assets—Other(13 )(13 )(11 )(13 )(50 )(13 )(14 )(14 )(41 )

Allocation of adjustments to noncontrolling interests 5 4 9(46 )(28 )(25 )(36 ) 3(58 )

(6 )(9 )(2 )(59 )(76 )(38 )(41 )(5 )(84 )

Total adjustments(12 )(34 )(19 ) 99 34 117 77(2,490 )(2,296 )

Less tax effect for above items 1 10 4(39 )(24 )(47 )(32 ) 925 846

Adjustments for tax-related items [1] 1 4 2 101 108(20 ) 14(3 )(9 )

Adjusted income from continuing operations available to common stockholders $ 152 $ 129 $ 130 $ 148 $ 559 $ 190 $ 158 $ 110 $ 458

Adjusted diluted earnings per common share [2] $ .22 $ .19 $ .19 $ .22 $ .81 $ .28 $ .23 $ .15 $ .64

687,143 686,924 687,306 687,712 687,185 688,904 700,696 752,064 714,119

Weighted-average shares—diluted (thousands)

[1] The fourth quarter of 2013 includes a favorable adjustment to reflect taxes on undistributed earnings of certain foreign operations that are no longer considered permanently reinvested. The first quarter of 2014 includes

an unfavorable adjustment related to completing the dropdown of certain Canadian operations to Williams Partners. The second quarter of 2014 includes a favorable adjustment to reflect taxes on undistributed earnings

of certain foreign operations that are no longer considered permanently reinvested.

[2] Interest expense, net of tax, associated with our convertible debentures has been added back to adjusted income from continuing operations available to common stockholders to calculate adjusted diluted earnings per

common share.

Note: The sum of earnings per share for the quarters may not equal the total earnings per share for the year due to changes in the weighted-average number of common shares outstanding.

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WMB Non-GAAP Reconciliations

Non-GAAP reconciliation schedule adjusted segment

profit (loss) and adjusted segment profit +DD&A

2013 2014

(Dollars in millions) 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr Year 1st Qtr 2nd Qtr 3rd Qtr Year

Segment profit (loss):

Williams Partners $ 494 $ 427 $ 411 $ 345 $ 1,677 $ 503 $ 393 $ 373 $ 1,269

Access Midstream Partners — 29 6 26 61 6 9 2,563 2,578

Williams NGL & Petchem Services(2 )(1 )(4 )(25 )(32 )(100 )(8 )(3 )(111 )

Other(5 ) 1(1 ) —(5 ) 3 1 1 5

Total segment profit (loss) $ 487 $ 456 $ 412 $ 346 $ 1,701 $ 412 $ 395 $ 2,934 $ 3,741

Segment adjustments:

Williams Partners $(6 ) $ 1 $(17 ) $ 143 $ 121 $ 60 $ 119 $(7 ) $ 172

Access Midstream Partners —(26 ) —(5 )(31 ) —(2 )(2,478 )(2,480 )

Williams NGL & Petchem Services — — — 20 20 95 1 — 96

Other — — — — — — — — —

Total segment adjustments $(6 ) $(25 ) $(17 ) $ 158 $ 110 $ 155 $ 118 $(2,485 ) $(2,212 )

Adjusted segment profit (loss):

Williams Partners $ 488 $ 428 $ 394 $ 488 $ 1,798 $ 563 $ 512 $ 366 $ 1,441

Access Midstream Partners — 3 6 21 30 6 7 85 98

Williams NGL & Petchem Services(2 )(1 )(4 )(5 )(12 )(5 )(7 )(3 )(15 )

Other(5 ) 1(1 ) —(5 ) 3 1 1 5

Total adjusted segment profit (loss) $ 481 $ 431 $ 395 $ 504 $ 1,811 $ 567 $ 513 $ 449 $ 1,529

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WMB Non-GAAP Reconciliations

Non-GAAP reconciliation schedule adjusted segment

profit (loss) and adjusted segment profit +DD&A

2013 2014

(Dollars in millions) 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr Year 1st Qtr 2nd Qtr 3rd Qtr Year

Depreciation and amortization (DD&A):

Williams Partners $ 196 $ 191 $ 201 $ 203 $ 791 $ 208 $ 207 $ 209 $ 624

Access Midstream Partners* 17 15 16 15 63 15 15 175 205

Williams NGL & Petchem Services — — — — — — 1(1 ) —

Other 5 7 6 6 24 6 6 6 18

$ 229 $ 229 $ 389 $ 847

Total depreciation and amortization $ 218 $ 213 $ 223 $ 224 $ 878

Adjusted segment profit (loss) + DD&A:

Williams Partners $ 684 $ 619 $ 595 $ 691 $ 2,589 $ 771 $ 719 $ 575 $ 2,065

Access Midstream Partners 17 18 22 36 93 21 22 260 303

Williams NGL & Petchem Services(2 )(1 )(4 )(5 )(12 )(5 )(6 )(4 )(15 )

Other — 8 5 6 19 9 7 7 23

Total adjusted segment profit (loss) + DD&A $ 699 $ 644 $ 618 $ 728 $ 2,689 $ 796 $ 742 $ 838 $ 2,376

* DD&A adjustment for Access Midstream Partners reflects the amortization of the basis difference between Williams’ investments and its proportional share of the underlying net assets.

Note: Segment profit (loss) includes equity earnings (losses) and income (loss) from investments reported in other investing income (loss)—net in the Consolidated Statement of Income. Equity earnings

(losses) results from investments accounted for under the equity method. Income (loss) from investments results from the management of certain equity investments.

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WMB Non-GAAP Reconciliations

WMB schedule of expected adjustments

(dollars in millions)

Segment Profit Adjustments: 2014 2015

Williams Partners (WPZ)

Loss related to compressor station fire $6 -

Impairment of certain equipment held for sale 17 -

Net gain related to partial acreage dedication release(12) -

Loss related to Opal incident 6 -

Loss related to Geismar incident 5 -

Geismar incident adjustment for insurance and timing(115) -

Other -(136)

Total Williams Partners adjustments(93)(136)

Williams NGL & Petchem Services

Bluegrass Pipeline project development costs (100% consolidated) 19 -

Bluegrass Pipeline and Moss Lake project development costs (50% equity investment losses) 7 -

Equity investment losses related to Bluegrass Pipeline and Moss Lake write-offs 70 -

Total Williams NGL & Petchem Services adjustments 96 -

Access Midstream Partners

Equity method investment in ACMP remeasurement gain(2,522) -

WMB impact of ACMP transaction-related compensation expenses 24 -

Gain associated with ACMP equity issuance(5) -

Acquisition-related expenses 15 -

Transition costs 8 -

Total Access Midstream Partners adjustments(2,480) -

Adjustments included in segment profit (loss)($2,477)($136)

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WPZ Non-GAAP Reconciliations

WPZ Non-GAAP Disclaimer

This presentation includes certain financial measures, adjusted segment profit, adjusted segment profit + DD&A, distributable cash flow, and cash distribution coverage ratio that are non-GAAP financial measures as defined under the rules of the Securities and Exchange Commission.

For Williams Partners L.P., adjusted segment profit excludes items of income or loss that we characterize as unrepresentative of our ongoing operations and may include assumed business interruption insurance related to the Geismar plant. Adjusted segment profit + DD&A is further adjusted to add back depreciation and amortization expense. Management believes these measures provide investors meaningful insight into Williams Partners L.P.‘s results from ongoing operations.

For Williams Partners L.P. we define distributable cash flow as net income plus depreciation and amortization and cash distributions from our equity investments less our earnings from equity investments, income attributable to noncontrolling interests and maintenance capital expenditures. We also adjust for reimbursements under omnibus agreements with Williams and certain other adjustments. Total distributable cash flow is reduced by any amounts associated with operations which occurred prior to our ownership of the underlying assets to arrive at distributable cash flow attributable to partnership operations.

For Williams Partners L.P. we also calculate the ratio of distributable cash flow attributable to partnership operations to the total cash distributed (cash distribution coverage ratio). This measure reflects the amount of distributable cash flow relative to our cash distribution. We have also provided this ratio calculated using the most directly comparable GAAP measure, net income.

This presentation is accompanied by a reconciliation of these non-GAAP financial measures to their nearest GAAP financial measures. Management uses these financial measures because they are accepted financial indicators used by investors to compare company performance. In addition, management believes that these measures provide investors an enhanced perspective of the operating performance of the Partnership’s assets and the cash that the business is generating. Neither adjusted segment profit, adjusted segment profit + DD&A, nor distributable cash flow are intended to represent cash flows for the period, nor are they presented as an alternative to net income or cash flow from operations. They should not be considered in isolation or as substitutes for a measure of performance prepared in accordance with United States generally accepted accounting principles.

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WPZ Non-GAAP Reconciliations

Reconciliation of non-GAAP distributable cash

flow to GAAP net income

2013 2014

(Dollars in millions, except coverage ratios) 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr Year 1st Qtr 2nd Qtr 3rd Qtr Year

Williams Partners L.P.

Reconciliation of Non-GAAP “Distributable cash flow” to GAAP “Net income”

Net income $ 344 $ 272 $ 285 $ 218 $ 1,119 $ 352 $ 234 $ 218 $ 804

Income attributable to noncontrolling interests — — —(3 )(3 ) —(2 )(1 )(3 )

Depreciation and amortization 196 191 201 203 791 208 207 209 624

Non-cash amortization of debt issuance costs included in interest expense 3 4 4 3 14 4 3 4 11

Equity earnings from investments(18 )(35 )(31 )(20 )(104 )(23 )(32 )(36 )(91 )

Allocated reorganization-related costs 2 — — — 2 — — — —

Impairment of certain equipment held for sale — — — — — — 17 — 17

Loss related to Geismar Incident — 6 4 4 14 — — 5 5

Geismar Incident adjustment for insurance and timing — —(35 ) 118 83 54 96 — 150

Contingency loss — — 9 16 25 — — — —

Reimbursements from Williams under omnibus agreements 4 4 2 3 13 3 4 1 8

Loss related to Opal incident — — — — — — 6 — 6

Plymouth incident adjustment — — — — — — 3 3 6

Canadian income tax — — — — — — 4 8 12

Income related to partial acreage dedication release — — — — — — —(12 )(12 )

Maintenance capital expenditures(44 )(76 )(79 )(59 )(258 )(36 )(90 )(103 )(229 )

Distributable cash flow excluding equity investments 487 366 360 483 1,696 562 450 296 1,308

Plus: Equity investments cash distributions to Williams Partners L.P. 38 41 34 41 154 43 54 71 168

Distributable cash flow 525 407 394 524 1,850 605 504 367 1,476

Less: Pre-partnership distributable cash flow 28 20 16 15 79 23 — — 23

Distributable cash flow attributable to partnership operations $ 497 $ 387 $ 378 $ 509 $ 1,771 $ 582 $ 504 $ 367 $ 1,453

Total cash distributed $ 473 $ 489 $ 442 $ 556 $ 1,960 $ 566 $ 577 $ 587 $ 1,730

Coverage ratios:

Distributable cash flow attributable to partnership operations divided by Total cash distributed 1.05 0.79 0.86 0.92 0.90 1.03 0.87 0.63 0.84

Net income divided by Total cash distributed 0.73 0.56 0.64 0.39 0.57 0.62 0.41 0.37 0.46

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WPZ Non-GAAP Reconciliations

Adjusted segment profit reconciliation and

adjusted segment profit + DD&A

2013 2014

(Dollars in millions) 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr Year 1st Qtr 2nd Qtr 3rd Qtr Year

Segment profit (loss):

Northeast G&P $(9 ) $ 12 $(1 ) $(26 ) $(24 ) $ 6 $ 15 $ 35 $ 56

Atlantic-Gulf 159 152 137 166 614 165 168 162 495

West 186 162 207 186 741 165 152 175 492

NGL & Petchem Services 158 101 68 19 346 167 58 1 226

Total segment profit (loss) $ 494 $ 427 $ 411 $ 345 $ 1,677 $ 503 $ 393 $ 373 $ 1,269

Segment adjustments:

Northeast G&P

Share of impairments at equity method investee $ — $ — $ — $ 7 $ 7 $ — $ — — $ —

Contingency loss — — 9 16 25 — — — —

Loss related to compressor station fire — — — — — 6 — — 6

Net gain related to partial acreage dedication release — — — — — — —(12 )(12 )

Impairment of certain equipment held for sale — — — — — — 17 — 17

Total Northeast G&P adjustments — — 9 23 32 6 17(12 ) 11

Atlantic-Gulf

Litigation settlement gain(6 ) — — —(6 ) — — — —

Net loss (recovery) related to Eminence storage facility leak —(5 ) 5(2 )(2 ) — — — —

Total Atlantic-Gulf adjustments(6 )(5 ) 5(2 )(8 ) — — — —

West

Loss related to Opal incident — — — — — — 6 — 6

Total West adjustments — — — — — — 6 — 6

NGL & Petchem Services

Loss related to Geismar Incident — 6 4 4 14 — — 5 5

Geismar Incident adjustment for insurance and timing — —(35 ) 118 83 54 96 — 150

Total NGL & Petchem Services adjustments — 6(31 ) 122 97 54 96 5 155

Total segment adjustments $(6 ) $ 1 $(17 ) $ 143 $ 121 $ 60 $ 119 $(7 ) $ 172

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WPZ Non-GAAP Reconciliations

Adjusted segment profit reconciliation and

adjusted segment profit + DD&A cont’d

2013 2014

(Dollars in millions) 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr Year 1st Qtr 2nd Qtr 3rd Qtr Year

Adjusted segment profit (loss):

Northeast G&P $(9 ) $ 12 $ 8 $(3 ) $ 8 $ 12 $ 32 $ 23 $ 67

Atlantic-Gulf 153 147 142 164 606 165 168 162 495

West 186 162 207 186 741 165 158 175 498

NGL & Petchem Services 158 107 37 141 443 221 154 6 381

Total adjusted segment profit (loss) $ 488 $ 428 $ 394 $ 488 $ 1,798 $ 563 $ 512 $ 366 $ 1,441

Depreciation and amortization (DD&A):

Northeast G&P $ 29 $ 32 $ 33 $ 38 $ 132 $ 39 $ 40 41 $ 120

Atlantic-Gulf 93 87 92 91 363 94 91 91 276

West 61 58 58 59 236 58 60 60 178

NGL & Petchem Services 13 14 18 15 60 17 16 17 50

Total depreciation and amortization $ 196 $ 191 $ 201 $ 203 $ 791 $ 208 $ 207 $ 209 $ 624

Adjusted segment profit (loss) + DD&A:

Northeast G&P $ 20 $ 44 $ 41 $ 35 $ 140 $ 51 $ 72 64 $ 187

Atlantic-Gulf 246 234 234 255 969 259 259 253 771

West 247 220 265 245 977 223 218 235 676

NGL & Petchem Services 171 121 55 156 503 238 170 23 431

Total adjusted segment profit (loss) + DD&A $ 684 $ 619 $ 595 $ 691 $ 2,589 $ 771 $ 719 $ 575 $ 2,065

Note: Segment profit (loss) includes equity earnings (losses) and income (loss) from investments reported in other income (expense)—net below operating income

in the Consolidated Statement of Comprehensive Income. Equity earnings (losses) result from investments accounted for under the equity method. Income

(loss) from investments results from the management of certain equity investments.

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WPZ Non-GAAP Reconciliations

Segment profit guidancereported to adjusted

Dollars in millions 2014 Guidance 2015 Guidance 2016 Guidance

Low Midpoint High Low Midpoint High Low Midpoint High

Reported segment profit:

Northeast G&P $184 $491

Atlantic—Gulf 630 965

West 614 595

NGL & Petchem Services 1,010 915

Unallocated Revisions(335) * -

Total reported segment profit 1,953 2,103 2,253 2,746 2,966 3,186 2,925 3,225 3,525

Adjustments:

Loss related to compressor station fire 6 6 6 —

Impairment of certain equipment held for sale 17 17 17 — — —

Net gain related to partial acreage dedication release(12)(12)(12) — — —

Other — -(136)(136)(136) — -

Total adjustments—Northeast G&P 11 11 11(136)(136)(136) — -

Total adjustments—Atlantic—Gulf — — — — -

Loss related to Opal incident 6 6 6 — — —

Total adjustments—West 6 6 6 — — —

Geismar incident adjustment for insurance and timing(115)(115)(115) — — —

Loss related to Geismar incident 5 5 5 — — —

Total adjustments—NGL & Petchem Services(110)(110)(110) — — —

Total segment profit adjustments(93)(93)(93)(136)(136)(136) — -

Adjusted segment profit:

Northeast G&P 195 355

Atlantic—Gulf 630 965

West 620 595

NGL & Petchem Services 900 915

Unallocated Revisions(335) * -

Total adjusted segment profit $1,860 $2,010 $2,160 $2,610 $2,830 $3,050 $2,925 $3,225 $3,525

Guidance does not reflect impact of WPZ/AMCP merger agreement as announced on 10/26/14.

Notes: * Unallocated revisions of $195 (low/mid/high) as previously announced in ACMP acquisition press release on 6/15/14 and $190 low /

$140 mid / $90 high as announced in WPZ press release on 7/30/14.

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WPZ Non-GAAP Reconciliations

WPZ adjusted segment profit + DD&A

Dollars in millions 2014 Guidance 2015 Guidance 2016 Guidance

Low Midpoint High Low Midpoint High Low Midpoint High

Adjusted segment profit:

Northeast G&P $195 $355

Atlantic—Gulf 630 965

West 620 595

NGL & Petchem Services 900 915

Unallocated Revisions(335) * -

Total adjusted segment profit 1,860 $2,010 2,160 2,610 2,830 3,050 2,925 3,225 3,525

Depreciation, Depletion and Amortiz. (DD&A):

Northeast G&P 170 210

Atlantic—Gulf 430 495

West 235 235

NGL & Petchem Services 75 95

Total DD&A 885 910 935 1,010 1,035 1,060 1,105 1,130 1,155

Adjusted segment profit + DD&A:

Northeast G&P 365 565

Atlantic—Gulf 1,060 1,460

West 855 830

NGL & Petchem Services 975 1,010

Unallocated Revisions(335) * -

Total adjusted segment profit + DD&A $2,745 $2,920 $*3,095 $3,620 $3,865 $4,110 $4,030 $4,355 $4,680

Guidance does not reflect impact of WPZ/AMCP merger agreement as announced on 10/26/14.

Notes: * Unallocated revisions of $195 (low/mid/high) as previously announced in ACMP acquisition press release on 6/15/14 and $190 low / $140 mid / $90 high as announced in WPZ press release on 7/30/14.

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WPZ Non-GAAP Reconciliations

Distributable cash flow (DCF) and DCF per

common unit

Dollars in millions 2013 2014 Guidance 2015 Guidance 2016 Guidance

Actual Low Midpoint High Low Midpoint High Low Midpoint High

Net Income (After Tax) 1,119 $1,406 1,566 $1,726 $1,850 $2,035 $2,220 $2,000 $2,290 $2,580

D D & A 791 885 910 935 1,010 1,035 1,060 1,105 1,130 1,155

Maintenance Capex(258)(305)(340)(375)(295)(325)(355)(300)(330)(360)

Attributable to Noncontrolling Interests(3)(30)(35)(40)(100)(105)(110)(130)(135)(140)

Geismar incident adjustment for insurance and timing 97(115)(115)(115) — — —

Other / Rounding 104(18)(13)(8) 140 145 150 125 130 135

Distributable Cash Flow 1,850 1,823 1,973 2,123 2,605 2,785 2,965 2,800 3,085 3,370

Less: Pre-Partnership Distributable Cash Flow 79 23 23 23 — — —

Distributable Cash Flow Attributable to Partnership Operations $1,771 $1,800 $1,950 $2,100 $2,605 $2,785 $2,965 $2,800 $3,085 $3,370

Cash Distributions 1 $1,960 $2,340 $2,370 $2,400 $2,632 $2,714 $2,796 $2,868 $2,950 $3,032

Cash Distribution Coverage Ratio 0.90x 0.77x 0.82x 0.88x 0.99x 1.03x 1.06x 0.98x 1.05x 1.11x

Net Income / Cash Distributions 0.57x 0.60x 0.66x 0.72x 0.70x 0.75x 0.79x 0.70x 0.78x 0.85x

Distributable Cash Flow (DCF) Attributable to Partnership Operations $1,771 $1,800 $1,950 $2,100 $2,605 $2,785 $2,965 $2,800 $3,085 $3,370

Allocation to General Partner 472 717 735 752 873 916 958 972 1,024 1,075

Allocation to Common Units 1,299 1,083 1,216 1,348 1,732 1,870 2,007 1,828 2,062 2,295

Weighted Average Common Units Outstanding (millions) 420.9 450.2 450.2 450.1 460.3 460.1 459.9 481.2 473.2 465.3

DCF Attributable to Partnership Operations Per Common Unit $3.09 $2.41 $2.70 $2.99 $3.76 $4.06 $4.36 $3.80 $4.36 $4.93

Guidance does not reflect impact of WPZ/AMCP merger agreement as announced on 10/26/14.

Note: Net Income presented above is on an after tax basis but was presented on a pretax basis in prior guidance. 1 Distributions

reflect per-unit increases of 5%—7% annually in 2014 and 2015, and 3%-6% in 2016.

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Non-GAAP Disclaimer

This presentation includes combined adjusted EBITDA for Williams Partners and Access Midstream Partners for 2015 and cash distribution coverage ratio, which are non-GAAP financial measures as defined under the rules of the SEC.

For Williams Partners L.P. we define adjusted EBITDA as net income (loss) attributable to partnership before income tax expense, net interest expense, depreciation and amortization expense, equity earnings from investments and allowance for equity funds used during construction, adjusted for equity investments cash distributions to partnership and certain other items management believes affect the comparability of operating results.

Access Midstream Partners defines adjusted EBITDA as net income (loss) before income tax expense, interest expense, depreciation and amortization expense and certain other items management believes affect the comparability of operating results.

For Williams Partners L.P. we also calculate the ratio of distributable cash flow to the total cash distributed (cash distribution coverage ratio). This measure reflects the amount of distributable cash flow relative to our cash distribution. We define distributable cash flow as net income plus depreciation and amortization and cash distributions from our equity investments less our earnings from our equity investments, income attributable to noncontrolling interests and maintenance capital expenditures. We also adjust for payments and/or reimbursements under omnibus agreements with Williams and certain other items.

This presentation is accompanied by a reconciliation of adjusted EBITDA to its nearest GAAP financial measure. Management uses this financial measure because it is an accepted financial indicator used by investors to compare company performance. In addition, management believes that this measure provides investors an enhanced perspective of the operating performance of the partnership’s assets and the cash that the business is generating. Adjusted EBITDA is not intended to represent cash flows for the period, nor is it presented as an alternative to net income or cash flow from operations. It should not be considered in isolation or as substitutes for a measure of performance prepared in accordance with United States generally accepted accounting principles

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Net Income After Tax Reconciliation to 2015

Adjusted EBITDA

Williams Access

Partners Midstream Combined*

Low High Low High Low High

Net income after tax attributable to partnership $1,755 $2,105 $ 470 $ 645

Net interest expense 645 665 225 175

Income tax expense 45 55 5 5

Equity earnings from investments(310)(340) —

Equity investments cash distributions to partnership 360 400 —

Depreciation & amortization (DD&A) 1,010 1,060 550 525

Equity allowance for funds used during construction(90)(100) —

Adjusted EBITDA attributable to partnership $3,415 $3,845 $ 1,250 $1,350 $4,665 $ 5,195