1-this ratio is net profit after tax by total revenue

2. total revenue include interest and bank operations such as Commissions ,investment revenue,Letter of Guarantee Revenues and other service's revenue

A bank's financial statements are highly similar to other company financial statements. However, much of a bank's assets shown on the balance sheet are represented by loans. Banks must therefore hold cash in reserve to comply with federal reserve capital requirements. How much they hold in reserve depends on the the total amount of loans and the quality of the loans. Revenue generated from interest assessed on the loans shows up on the income statement as do losses that arise from the write-off or write-down of bad loans.

The 3 common performance indicators for as bank are Net Interest Margin, Cost-to-Income and ROA. Net interest margin is calculated as net interest income minus net interest expenses divided by interest bearing assets. Cost-to-Income is calculated as Operating expenses (sometimes including amortisation, sometimes without- without is usually better as amortisation depends on accounting policy) divided by Operating Income. ROA is calculated as Net Income divided by Total (or average total ) assets. Profit margin would be Net Income (after tax) divided by total revenues, but it is not much used as ROA is considered to be more indicative (a bank makes money on its assets; capital, which is a bank's scarce resource is calculated on assets).

The performance indicators are fine if derived from Statutory/Independent Audit Reports or Regulators' Reports.

For banks, the operating profit margin is obtained by dividing the operating profit by the Gross Operating Earnings of the bank. This matches like terms to like terms. The income being referred to here is the gross operating earnings of the bank that gives rise to operating profit. the Operating profit is the Earnings before interest and tax (EBIT).

Logically, it should include all items you mention. It should however exclude unusual or extraordinary items like sale of assets or sale of investment in subsidiaries & the like. While arriving at Net Interest Margin, Interest income & Interest expenditure are only taken.

For Net Interest Margin, Interest income & Interest expenditure are only taken. You are very correct Emmanuel.

Agree to above views.

https://books.google.com.bd/books?id=Zp-bKgAACAAJ&dq=commercial+bank+management&hl=en&sa=X&ved=0ahUKEwjyuqvJ0praAhUgSo8KHe1dBEEQ6AEIJTAA

To overcome these challenges, in Financial Institutions, we use NIM, which is Net Interest Margin. This is average interest earned on the portfolio divided by the average interest cost of funds.

NIM is net interest margin. For sure, the correct computational method is interest income minus interest expense and the difference is divided by interest income. Please let there be no confusion on the actual meaning of NIM.

non-interest margin is very important here which is the rest of net profit margin or the none operating profit . which equals the following= 1-

interest income minus interest expense as the difference divided by interest income.