Abstract Changes in stock prices in the market are considered normal; but, the issue that always worries investors is the issue of sudden changes in stock prices. Also, one of the major sources of information used by capital market participants is the financial reports published by the companies, periodically made available to the public as the basis for the potential and actual investor decisions to buy and sell and invest in the stock market. Therefore, the ethical behaviour of managers in the organisation is considered as a key factor in the success of the organisation and gaining the trust of investors. Therefore, based on this argument, the purpose of this study is to design a model to examine the weak managers' ethical behaviours on stock price crash risk and financial reporting quality using a sample of 134 companies listed on the Tehran Stock Exchange from 2018 to 2020. Also, the research hypotheses test was conducted using structural equation modelling. The results showed that the weak ethical behaviours of managers in the companies increase stock price crash risk. The second hypothesis also shows that the weak managers' ethical behaviours also reduce financial reporting quality
