Keith Meister, Eric Mandelblatt Step Down from Williams Companies (WMB) Board

Page 10 of 12

Page 10 of 12 – SEC Filing

Item 4. Purpose of Transaction.

On June 30, 2016, Mr. Meister and Mr. Mandelblatt resigned from
the Board of Directors (the Board) of the Issuer. In connection with the resignations of Mr. Meister and Mr. Mandelblatt from the Board, each of Mr. Meister and Mr. Mandelblatt delivered a letter to the Board describing the
reasons for such resignations. A copy of the letter to the Board delivered by Mr. Meister is attached hereto as Exhibit 2 and is incorporated herein by reference. A copy of the letter to the Board delivered by Mr. Mandelblatt is attached
hereto as Exhibit 3 and is incorporated herein by reference.

As a result of such resignations, the previously disclosed Agreement referenced in
Item 6 was terminated.

The Reporting Persons intend to review their respective investment in the Issuer on a continuing basis and may from time to
time and at any time in the future depending on various factors, including, without limitation, the Issuers financial position and strategic direction, actions taken by the Board, price levels of the Shares, other investment opportunities
available to the Reporting Persons, conditions in the securities market and general economic and industry conditions, take such actions with respect to their respective investments in the Issuer as they deem appropriate, including, without
limitation: (i) acquiring additional Shares and/or other equity, debt, notes, other securities, or derivative or other instruments that are based upon or relate to the value of the Shares or the Issuer (collectively, Securities) of the
Issuer in the open market or otherwise; (ii) disposing of any or all of their Securities in the open market or otherwise; (iii) engaging in any hedging or similar transactions with respect to the Securities; or (iv) proposing or considering one or
more of the actions described in subsections (a) through (j) of Item 4 of Schedule 13D.

Item 5. Interest in Securities of the Issuer.

(a) (b) The Corvex Persons may be deemed to be the
beneficial owner of 41,682,960 Shares, which collectively represent approximately 5.6% of the Issuers outstanding Shares. Corvex may be deemed to have sole power to vote and sole power to dispose of 41,682,960 Shares. By virtue of his position
as control person of the general partner of Corvex, Mr. Meister may be considered to beneficially own such Shares.

The Soroban Persons may be deemed
to be the beneficial owner of 21,000,000 Shares, which represent approximately 2.8% of the Issuers outstanding Shares. Each of the Soroban Persons may be deemed to have shared power to vote and dispose of such Shares.

The aggregate Shares reported as beneficially owned by the Corvex Persons and the Soroban Persons is 62,682,960 Shares, which collectively represent
approximately 8.4% of the Issuers outstanding Shares.

The percentages calculated in the immediately foregoing paragraph and in the paragraphs above
are calculated based on a total of 750,569,517 Shares outstanding as of May 19, 2016, as reported in the Form S-4 filed with the SEC by Energy Transfer Corp LP on May 25, 2016.

The filing of this Schedule 13D shall not be construed as an admission that any of the Reporting Persons is the beneficial owner of any securities covered by
the Schedule 13D except to the extent expressly noted herein.

(c) There have been no transactions with respect to the Shares during the sixty days prior
to the date hereof by any of the Reporting Persons.

(d) Except as set forth below, no person is known to have the right to receive, or the power to
direct the receipt of dividends from, or proceeds from the sale of, the Shares beneficially owned by any of the Reporting Persons, other than the Reporting Persons themselves.

The limited partners of (or investors in) each of the private investment funds for which Corvex or its affiliates acts as general partner and/or investment
adviser have the right to participate in the receipt of dividends from, or proceeds from the sale of, the Shares held for the accounts of their respective funds in accordance with their respective limited partnership interests (or investment
percentages) in their respective funds.

The limited partners of (or investors in) each of the private investment funds for which SCP LP or its affiliates
acts as general partner, managing member and/or investment manager have the right to participate in the receipt of dividends from, or proceeds from the sale of, the Shares held for the accounts of their respective funds in accordance with their
respective limited partnership interests, limited liability company interests or investment percentages in their respective funds.

Follow Williams Companies Inc. (NYSE:WMB)

Page 10 of 12