UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 6)

Tower Semiconductor Ltd.

(Name of Issuer)

Ordinary Shares, NIS 15.00 par value per share

(Title of Class of Securities)

M87915-10-0

(CUSIP Number)

Ronen Meidan

Bank Hapoalim B.M.

63 Yehuda Halevi St.

Tel Aviv 6578109, Israel

972-3-5674174

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

August 29, 2014

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.  ¨

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.

The statement on Schedule 13D, dated February 3, 2011, of Bank Hapoalim B.M. (“Hapoalim”) and Tarshish Hahzakot Vehashkaot Hapoalim Ltd. (“Tarshish”) (collectively, the “Reporting Persons”), as amended by Amendment No. 1 thereto, dated June 10, 2013, Amendment No. 2 thereto, dated June 24, 2013, Amendment No. 3 thereto, dated July 22, 2013, Amendment No. 4 thereto, dated January 15, 2014 and Amendment No. 5 thereto, dated June 6, 2014, is hereby further amended as follows:

Schedule A is hereby amended to read in its entirety as attached hereto and incorporated by reference.

Item 5(a)-(c) is hereby amended to read in its entirety as follows:

“To the knowledge of the Reporting Persons:

Set forth below are the dates of sale, number and average price per share of Ordinary Shares sold by Hapoalim on NASDAQ.

Item 5(d) is hereby amended by deleting the last sentence thereof and substituting the following therefor:

“Based on Amendment No. 7 to Leumi’s Statement on Schedule 13D filed with the Commission on August 7, 2014, Leumi ceased to be a beneficial owner of more than five percent of the Ordinary Shares.”

Signature

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

SCHEDULE A

Information Regarding Senior Officers and Directors of Bank Hapoalim B.M.

Board of Directors

Senior Officers

PRINCIPAL HOLDERS OF THE

ISSUED SHARE CAPITAL OF BANK HAPOALIM B.M.

Arison Holdings (1998) Ltd.—Director Information

Salt Of The Earth Ltd.—Director Information

Information Regarding Senior Officers and Directors

of Tarshish Hahzakot Vehashkaot Hapoalim Ltd.

Board of Directors