UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of May, 2019

Commission File Number 001-37928

ChipMOS TECHNOLOGIES INC.

(Translation of Registrant’s Name Into English)

No. 1, R&D Rd. 1, Hsinchu Science Park

Hsinchu, Taiwan

Republic of China

(Address of Principal Executive Offices)

(Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.)

Form 20-F  ☒             Form 40-F  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):  ☐

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, thereunto duly authorized.

2

ChipMOS REPORTS FIRST QUARTER 2019 RESULTS

Q1’19 Highlights (as compared to Q4’18):

Hsinchu, Taiwan - 5/7/2019 - ChipMOS TECHNOLOGIES INC. (“ChipMOS” or the “Company”) (Taiwan Stock Exchange: 8150 and NASDAQ: IMOS), an industry leading provider of outsourced semiconductor assembly and test services (“OSAT”), today reported unaudited consolidated financial results for the first quarter ended March 31, 2019. All U.S. dollar figures cited in this press release are based on the exchange rate of NT$30.86 against US$1.00 as of March 29, 2019.

All the figures were prepared in accordance with Taiwan-International Financial Reporting Standards (“Taiwan-IFRS”).

Revenue for the first quarter of 2019 was NT$4,462.0 million or US$144.6 million, a decrease of 10.3% from NT$4,972.3 million or US$161.1 million in the fourth quarter of 2018 and an increase of 11.2% from NT$4,010.9 million or US$130.0 million for the same period in 2018. The first quarter normally represents the low period of the year for the industry followed by quarterly revenue growth. This is due to fewer working days around the Chinese New Year Holiday and semiconductor chain inventory rebalancing at the start of the New Year.

Net profit attributable to equity holders of the Company for the first quarter of 2019 was NT$193.7 million or US$6.3 million, and NT$0.27 or US$0.01 per basic common share, as compared to net profit attributable to equity holders of the Company for the fourth quarter of 2018 of NT$516.6 million or US$16.8 million, and NT$0.71 or US$0.02 per basic common share, and compared to net profit attributable to equity holders of the Company in the first quarter of 2018 of NT$22.8 million or US$0.7 million, and NT$0.03 or US$0.001 per basic common share. Net earnings for the first quarter of 2019 were US$0.17 per basic ADS, compared to US$0.46 per basic ADS for the fourth quarter of 2018 and US$0.02 per basic ADS in the first quarter of 2018.

S.J. Cheng, Chairman and President of ChipMOS, said, “We continue to take action in our business and focus on the priority growth drivers, while further improving our balance sheet and working to build value for investors. Customer demand remains healthy in our TDDI and 12” fine pitch COF businesses with growth expected to continue led by higher demand for new bezel-less smartphone panels, 4K TVs, displays and other applications. Importantly, we believe we have moved beyond the typical low season having reported 19.2% revenue growth for the month of March 2019, as compared to the month of February 2019. We expect to benefit from further gains in our TDDI, and 12” fine pitch COF business, along with new customer programs in our NAND flash business. Finally, we are pleased to have realized a return in April on our strategic investment in JMC. The proceeds will be used to further strengthen our Company’s financial structure, while increasing our balance of working capital and decreasing the debt ratio.”

-1-

Silvia Su, Vice President of Finance and Accounting, commented, “We grew our revenue 11.2%, improved our gross profit by 14.4% and operating profit by 23.6% compared to the same period in 2018. We continue to manage our business to profitability, with the right resource level and operating structure to fully support our customers and new growth opportunities, including those in our DDIC business. We ended the first quarter with a balance of cash and cash equivalents of US$164.3 million, and a net debt balance of US$191.1 million. This does not reflect the proceeds from our JMC share sale in April, which will be recognized in Q2’19. CapEx was US$20.4 million in the first quarter, with the majority invested in expanding our DDIC capacity to meet customer demand levels, mainly for TDDI wafer test and 12” fine pitch COF. Reflecting our commitment to building shareholder value, and confidence in our business and financial position, our Board proposed on March 7, 2019 that NT$1.2 per common share or approximately US$0.78 per ADS be distributed to shareholders from earnings. This is pending shareholders’ approval at our AGM on June 10, 2019.”

Selected Operation Data

-2-

Investor Conference Call / Webcast Details

ChipMOS will host two conference calls on Tuesday, May 7, 2019 to discuss the Company’s financial results for the first quarter of 2019.

About ChipMOS TECHNOLOGIES INC.:

ChipMOS TECHNOLOGIES INC. (“ChipMOS” or the “Company”) (Taiwan Stock Exchange: 8150 and NASDAQ: IMOS) (https://www.chipmos.com) is an industry leading provider of outsourced semiconductor assembly and test services. With advanced facilities in Hsinchu Science Park, Hsinchu Industrial Park and Southern Taiwan Science Park in Taiwan, ChipMOS provide assembly and test services to a broad range of customers, including leading fabless semiconductor companies, integrated device manufacturers and independent semiconductor foundries.

Forward-Looking Statements

This press release may contain certain forward-looking statements. These forward-looking statements may be identified by words such as ‘believes,’ ‘expects,’ ‘anticipates,’ ‘projects,’ ‘intends,’ ‘should,’ ‘seeks,’ ‘estimates,’ ‘future’ or similar expressions or by discussion of, among other things, strategy, goals, plans or intentions. These statements may include financial projections and estimates and their underlying assumptions, statements regarding plans, objectives and expectations with respect to future operations, products and services, and statements regarding future performance. Actual results may differ materially in the future from those reflected in forward-looking statements contained in this document, due to various factors. Further information regarding these risks, uncertainties and other factors are included in the Company’s most recent Annual Report on Form 20-F filed with the U.S. Securities and Exchange Commission (the “SEC”) and in the Company’s other filings with the SEC.

About Non-Generally Accepted Accounting Principles (“Non-GAAP”) Financial Measures

To supplement the consolidated financial results presented in accordance with the Taiwan-IFRS, ChipMOS uses non-GAAP free cash flow, non-GAAP earnings before interest, taxes, depreciation and amortization (“EBITDA”) and non-GAAP net debt to equity ratio in this press release. The non-GAAP free cash flow represents operating profit plus depreciation, amortization and interest income and less capital expenditures, interest expense, income tax expense and dividend. The non-GAAP EBITDA represents operating profit plus depreciation and amortization. The non-GAAP net debt to equity ratio represents the ratio of net debt, the sum of debt less cash and cash equivalent, divided by equity attributable to equity holders of the Company. These non-GAAP financial measures may not be comparable to similarly titled measures presented by other companies. Other companies may calculate similarly titled measures differently.

The presentation of non-GAAP financial measures is not intended to be considered in isolation or as a substitute for the financial information prepared and presented in accordance with the Taiwan-IFRS.

ChipMOS considers the use of non-GAAP free cash flow, non-GAAP EBITDA and non-GAAP net debt to equity ratio provides useful information to management to manage the Company’s business and make financial and operational decisions and also to the investors to understand and evaluate the Company’s business and operating performance. For more information on these non-GAAP financial measures, please refer to the table captioned “Reconciliations of Non-GAAP Measures to the Nearest Comparable GAAP Measures” in this press release.

- FINANCIAL TABLES FOLLOW BELOW -

-3-

ChipMOS TECHNOLOGIES INC.

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

For the Three Months Ended Mar. 31, 2019, Dec. 31, and Mar. 31, 2018

Figures in Millions of U.S. dollars (USD) ⁽¹⁾

Except for Per Share Amounts and Weighted Average Shares Outstanding

Note:

-4-

ChipMOS TECHNOLOGIES INC.

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

For the Three Months Ended Mar. 31, 2019, Dec. 31, and Mar. 31, 2018

Figures in Millions of NT dollars (NTD)

Except for Per Share Amounts and Weighted Average Shares Outstanding

-5-

ChipMOS TECHNOLOGIES INC.

UNAUDITED CONSOLIDATED STATEMENTS OF FINANCIAL POSITION

As of Mar. 31, 2019, Dec. 31, and Mar. 31, 2018

Figures in Millions of U.S. dollars (USD) ⁽¹⁾

Note:

-6-

ChipMOS TECHNOLOGIES INC.

UNAUDITED CONSOLIDATED STATEMENTS OF FINANCIAL POSITION

As of Mar. 31, 2019, Dec. 31, and Mar. 31, 2018

Figures in Millions of NT dollars (NTD)

-7-

RECONCILIATIONS OF NON-GAAP MEASURES TO THE NEAREST COMPARABLE GAAP MEASURES

(Figures in Millions of U.S. dollars (USD))

The table below sets forth a reconciliation of our operating profit to non-GAAP free cash flow for the periods indicated:

The table below sets forth a reconciliation of our operating profit to non-GAAP EBITDA for the periods indicated:

The table below sets forth a calculation of our non-GAAP net debt to equity ratio for the periods indicated:

-8-