Purpose – This paper compares current requirements for depreciation accounting from the Financial Accounting Standards Board in America for equity securities and all debt securities with determinable fair value, and disclosure requirements related to the fair value of securities below registered cost with the requirements of the international Financial Reporting Standards Board and accounting standards committee. Research design, data, and methodology – Mini-review statements are examined relating to depreciation of investments in America and the Financial Accounting Standards depreciation of investments in Iran that meet the requirements of international reporting standards and the Iranian Accounting Standards Committee. Results – Accounting rules for depreciation of investments in securities requires a good deal of judgment. In particular, devaluation decisions during the recession and market crisis were controversial, although even with no clear guidelines on devaluation, sometimes such decisions were simple. Conclusions –Companies can choose from formal policies applied uniformly and documentations of interest to provide a summary of the principles and conclusions obtained through disclosure, enabling market participants to assess the entity's conclusions reasonably, thereby easing investor and market worries.