Shiraz University Iranian Journal of Economic Studies 2322-1402 Articles in Press 2021 01 19 Investigating the impact of Market Timing on the Capital Structure of Companies in Tehran Stock Market بررسی تأثیر زمان‌بندی بازار بر ساختار سرمایه شرکت‌ها در بورس اوراق بهادار تهران 6000 10.22099/ijes.2020.34169.1591 EN Parisa Mohajeri Parisa Mohajeri: Faculty of Economics, Allameh Tabataba’i University, Tehran, Iran (p.mohajeri@atu.ac.ir). TEL: 09122899683 Reza Taleblou Faculty of Economics, Allameh Tabataba'i University, Tehran, Iran Aylar Rahnama Aylar Rahnama: Faculty of Economics, Allameh Tabataba’i University, Tehran, Iran (a.rahnama@atu.ac.ir). Journal Article 2019 07 06 Based on the theory of market timing in the framework of capital structure, the time of issuing stock depends on the stock prices. In that way, managers are issuing shares that have a high ratio of market value to book value. In fact, issuing shares is in the best interest of the firm when the company's stock in the market is more than actually valued. <br>In this paper, by using panel data of 55 firms listed in the Tehran Stock Market during the 2003 to 2018, we investigate the impact of market timing on capital structure. The estimated model in this paper is a partial dynamic model using the Generalized Method of Moment (GMM) and Arrelano-Band Estimates. The findings indicate that: one- market timing has affected the firm`s capital structure of Tehran Stock Exchange.Two- market condition has a significant negative effect on capital structure which means that in the hot markets, managers issue more equity and less debt. Three- firm size and tangible assets have significant positive effects on leverage ratio. In fact, the larger firms with more tangible assets face lower default risks, thus they have relatively more debt. Four- profitability variable influences corporate leverage negatively. Five-sanction and exchange rate variables have negative significant effects on capital structure.