UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of report (Date of earliest event reported): September 25, 2013

None

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

A special meeting of the stockholders (the “Special Meeting”) of NV Energy, Inc. (“NVE”) was held on September 25, 2013. A total of 175,363,841 shares of NVE common stock were present in person or represented by proxy at the Special Meeting out of a total of 235,580,598 shares of NVE common stock issued and outstanding and entitled to vote as of the record date for the Special Meeting, which constituted a quorum. The tables below set forth the number of votes cast for and against, as well as the number of abstentions with respect to, each proposal voted on at the Special Meeting, as certified by the independent inspector of elections. Each of the proposals is described in detail in NVE’s proxy statement dated August 20, 2013 and first mailed to NVE’s stockholders on or about August 23, 2013.

Proposal 1: Approval of the Merger Agreement

NVE’s stockholders approved the Agreement and Plan of Merger, dated as of May 29, 2013 and as amended from time to time (the “Merger Agreement”), by and among MidAmerican Energy Holdings Company (“MidAmerican”), Silver Merger Sub, Inc. (“Merger Sub”) and NVE, pursuant to which, subject to the satisfaction or waiver of certain specified conditions, Merger Sub will merge with and into NVE, with NVE continuing as the surviving corporation and a wholly owned subsidiary of MidAmerican (the “Merger”). The proposal to approve the Merger Agreement required the affirmative vote of the holders of a majority of the outstanding shares of NVE common stock entitled to vote on the proposal at the Special Meeting. The proposal to approve the Merger Agreement received the affirmative vote of the holders of approximately 73% of the shares of NVE common stock entitled to vote at the Special Meeting:

Proposal 2: Non-Binding Compensation Advisory Proposal

NVE’s stockholders approved, on a non-binding advisory basis, the compensation that may be paid or become payable to NVE’s named executive officers that is based on or otherwise relates to the Merger. The approval of the non-binding compensation advisory proposal required the affirmative vote of the holders of a majority of the votes cast on the proposal at the Special Meeting. The non-binding compensation advisory proposal received the affirmative vote of the holders of approximately 52% of the votes cast at the Special Meeting in person or by proxy:

Proposal 3: Authority to Adjourn the Special Meeting

Because the proposal to approve the Merger Agreement received the affirmative vote of the holders of a majority of the outstanding shares of NVE common stock entitled to vote on the proposal at the Special Meeting, the vote on the proposal to adjourn the Special Meeting to a later date or time was not called.

On September 25, 2013, NVE issued a press release relating to the results of the vote at the Special Meeting. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.