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): June 18, 2015

WEST CORPORATION

(Exact Name of Registrant as Specified in Charter)

Registrant’s telephone number, including area code: (402) 963-1200

N/A

(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:

Item 1.01. Entry into a Material Definitive Agreement.

Underwriting Agreement

On June 18, 2015, West Corporation (“West” or the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) by and among the Company, Morgan Stanley & Co. LLC (the “Underwriter”), and the selling stockholders listed on Schedule I thereto (the “Selling Stockholders”). Pursuant to the Underwriting Agreement, the Selling Stockholders agreed to sell to the Underwriter 7,000,000 shares of the Company’s common stock, par value $0.001 per share (the “Common Stock”), at a price of $30.36 per share in an underwritten public offering (the “Offering”). The closing of the Offering occurred on June 24, 2015. All of the shares in the Offering were sold by the Selling Stockholders. The Company did not sell any shares in the Offering and did not receive any proceeds from the Offering. Pursuant to the Underwriting Agreement, the Underwriter has a 30-day option to purchase up to an additional 1,050,000 shares of Common Stock from the Selling Stockholders at a price of $30.36 per share.

The Offering was made pursuant to (i) a Registration Statement on Form S-3ASR (File No. 333-202622), which was filed with the Securities and Exchange Commission (the “SEC”) on March 9, 2015 and became effective upon filing, including a related base prospectus dated March 9, 2015, and (ii) a related prospectus supplement dated June 18, 2015, filed with the SEC on June 22, 2015.

The Underwriting Agreement contains customary representations, warranties and covenants of the parties and indemnification and contribution provisions under which the parties have agreed to indemnify each other against certain liabilities, including liabilities under the Securities Act of 1933, as amended.

The foregoing description of the Underwriting Agreement does not purport to be complete and is qualified in its entirety by reference to the Underwriting Agreement, a copy of which is filed herewith as Exhibit 1.1 and is incorporated by reference herein.

Stock Repurchase Agreement

On June 18, 2015, West entered into an agreement with the Selling Stockholders to repurchase 1,000,000 shares of Common Stock from the Selling Stockholders in a private transaction at the price at which the shares of Common Stock were sold to the Underwriter in the Offering, for an aggregate purchase price of approximately $30.4 million (the “Stock Repurchase Agreement”). The repurchase of shares of Common Stock pursuant to the Stock Repurchase Agreement occurred simultaneously with the closing of the Offering. The Stock Repurchase Agreement contains customary representations, warranties and covenants of the parties.

The foregoing description of the Stock Repurchase Agreement does not purport to be complete and is qualified in its entirety by reference to the Stock Repurchase Agreement, a copy of which is filed herewith as Exhibit 10.1 and is incorporated herein by reference.

Item 7.01. Regulation FD Disclosure.

On June 24, 2015, the Company issued a press release announcing the closing of the sale of the shares to be sold pursuant to the Underwriting Agreement and the Stock Repurchase Agreement. A copy of the press release is furnished with this Current Report on Form 8-K and attached hereto as Exhibit 99.1.

The foregoing information in this Item 7.01 (including the exhibit hereto) is being furnished under “Item 7.01. Regulation FD Disclosure.” Such information (including the exhibit hereto) shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, except as shall be expressly set forth by specific reference in such filing.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

The following is a list of the exhibits filed herewith.

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.

EXHIBIT INDEX