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

May 9, 2018

Date of Report (Date of earliest event reported)

TPI Composites, Inc.

(Exact name of registrant as specified in its charter)

8501 N. Scottsdale Rd, Gainey Center II, Suite 100, Scottsdale, AZ 85253

(Address of principal executive offices) (Zip Code)

480-305-8910

(Registrant’s telephone number, including area code)

Not applicable

(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:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☒

On May 9, 2018, TPI Composites, Inc. (the Company) issued a press release announcing that Vestas Wind Systems A/S has exercised an option under an existing, multiyear supply agreement for two additional blade manufacturing lines at Company’s new manufacturing facility in Matamoros, Mexico. A copy of the Company’s press release is furnished herewith as Exhibit 99.1 to this current report on Form 8-K and is incorporated by reference herein.

The information in Exhibit 99.1 of this current report on Form 8-K is being furnished and shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section. The information in Item 7.01 of this current report on Form 8-K (including Exhibit 99.1) shall not be incorporated by reference into any registration statement or other document pursuant to the Securities Act of 1933, as amended.

SIGNATURE

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 99.1

TPI and Vestas Expand Relationship in Mexico

Scottsdale, Ariz., May 9, 2018 (GLOBE NEWSWIRE) – TPI Composites, Inc., (TPI) (Nasdaq: TPIC), the only independent manufacturer of composite wind blades with a global footprint, announced today that Vestas Wind Systems A/S has exercised an option for two additional blade manufacturing lines under an existing multiyear supply agreement. TPI will produce blades for Vestas’ 4 MW wind turbine platform at TPI’s new facility in Matamoros, Mexico. The facility is scheduled to open for production in the third quarter of this year.

“We are pleased that Vestas has chosen to expand its relationships with TPI with the addition of two lines in Mexico for its 4MW platform,” said Steve Lockard, President and CEO of TPI Composites.

TPI has produced wind blades in Mexico since 2002, and currently operates three wind blade facilities in Ciudad Juarez.

About TPI Composites, Inc.

TPI Composites, Inc. is the only independent manufacturer of composite wind blades for the wind energy market with a global manufacturing footprint. TPI delivers high-quality, cost-effective composite solutions through long term relationships with leading wind turbine manufacturers. TPI is headquartered in Scottsdale, Arizona and operates factories throughout the U.S., China, Mexico, and Turkey.

Investor Contact:

investors@tpicomposites.com

480-315-8742