History and Methodology


The Turkey’s Top 500 Industrial Enterprises survey dates back to as early as the 1960s. The first survey, the “Top 100 Enterprises”, was publicly released in 1968. The scope of the annual survey, which reveals previous year’s results, was expanded to 300 enterprises in 1978, and to 500 in 1981.

In 1991, the “325 Industrial Enterprises Following the Top 500” survey was published in addition to the “Turkey’s Top 500 Industrial Enterprises” survey. Published under the title of “250 Industrial Enterprises Following the Top 500” between 1992 and 1997, this additional study was widened to cover 500 enterprises in 1998. Thus, data related to the Turkey’s Top 1000 Industrial Enterprises have been publicly released every year since 1998.

The “Turkey’s Top 500 Industrial Enterprises” survey is an important reflection on the Turkish economy. And it has been mentioned in numerous theses and academic studies to date.


The main objective of the “Turkey’s Top 500 Industrial Enterprises (İSO 500)” survey is to determine the largest enterprises engaged in industry in Turkey, identify their aggregates, and thus reveal the development of Turkish industry and help draw a road map for the future.

The “Turkey’s Top 500 Industrial Enterprises” is a survey-based study. Participation in the survey is voluntary.

The survey includes all enterprises that operate in industrial sectors across Turkey.

Since 2014, the survey data have been collected electronically. The survey asks for information about net sales, production-based sales, exports (in USD), pre-tax profit/loss for the period, earnings before interest, tax, depreciation and amortization (EBITDA), total assets and liabilities, annual average number of employees, R&D expenditures, and factor income payments through which gross value added is calculated (wages and salaries paid, interest paid, non-operating revenues, amortization and indirect taxes paid, provisions allocated from profit). The participants are also asked to provide their capital distribution and economic activities code (NACE Rev. 2).

The survey is based on the statements of enterprises. However, in order to verify the accuracy of the data, the enterprises are also requested to upload their Corporate Income Tax Return (e-return), which includes accumulated balance sheets and income statements prepared according to the Tax Procedure Law (TPL) to be submitted to the Ministry of Finance.

The information provided in the survey is checked against balance sheets and income statements, and in case of any discrepancy, the enterprise in question is contacted and asked to correct the discrepancy in writing. In case of unresolved discrepancies, balance sheet and income statement figures prevail.

As the “Turkey’s Top 500 Industrial Enterprises” survey aims to determine the largest industrial enterprises in Turkey, it also includes enterprises that do not wish to share their data. Data for such companies is used in all assessments, even though it is not publicly disclosed.

The “Turkey’s Top 500 Industrial Enterprises” survey is prepared for the industrial sector (mining and quarrying, manufacturing, and electricity, gas, steam and air conditioning supply sectors) based on the criterion of production-based sales (excluding sale of goods manufactured by the enterprises, and sale of commercial goods).

In addition to production-based sales, the survey ranks companies by their net sales, gross value added, equity capital, total assets, pre-tax profit and loss for the period, EBITDA, exports, and average number of employees.

The İSO Top 500 survey have used the European Union’s NACE Rev. 2 (Statistical Classification of Economic Activities) for sectoral classification since 2013. However, as a cumulative survey, the İSO Top 500 continues to use United Nations International Standard Industrial Classification of All Economic Activities (ISIC Rev. 2) to ensure continuity and facilitate comparisons with previous years.