[Analysis note] 4 major Korean banks-Profitability

During last winter vacation I did an internship in a Korean bank, so I had a chance to look into Korean banking industry.
Now I want to see 4 major banks in Korea and compare them in terms of financial indexes, but today I'm gonna upload post only about profitability as the first one.

<Profitability>
High profitability makes growth through reinvestment and future ability to secure a buffer against the crisis.

As a financial index for estimating profitability, Return on assets(ROA) measures the ability to create revenue and manage bad debt.

Using IR documents of each bank, I got this graph of ROA comparison through Excel.

Here roughly the Shinhan bank has the highest profitability. 

One noticeable thing is that the KB bank had very low profitability in 2010 but it jumped up in 2011. 

I did some research with various items in IR document and articles. 

Finally I found out KB bank amassed much loan loss reserve in 2010, which is the cause for low profitability in 2010 but high profitability in 2011.

As another financial index for profitability which is especially important in banking industry,   Net interest margin(NIM) is an indicator of return ratio on the bank's main assets(interest generating assets).

KB bank has the highest NIM. It's because it dominated market for low cost receiving credit in advance. On the other hand, Shinhan bank and hanabank are the last movers and they had disadvantages.