IMI has published this ranking for more than two decades. Current ranking, which is the 22nd, has been done according to the 1397 fiscal year's audited financial statement.
The sales index is not the only index of IMI rankings. IMI considers several other indexes such as profitability, added value, assets, employment, and efficiency. NAK is ranked 3rd in the telecommunication category and 191st in 500 best Iranian companies for its sales index (most sales recorded).