File photo of a customer handing a bundle of Indian rupee currency notes to a teller at financial institution in Mumbai. Reuters

As India’s economy enters some of its harshest conditions in recent times, the currency has devalued to nearly 69 rupees on the dollar and India’s central bank is now fighting to stave off the psychologically significant 70-rupee mark. Once this figure is breached, many believe foreign capital will start flowing out of the country at an unprecedented rate. Investors have already seen more than $1 billion worth of Indian shares leave the country since Tuesday. At a certain point, the so-called "3D" options will take hold: default, devaluation and deflation.

Once this happens the banks will start to feel the pinch. As in the United States during its financial crisis, the smaller banks will be hit first and many are unlikely to recover.

Here’s a list of the 10 Indian banks with the highest revenue.

10. Axis Bank, formerly known as the Unit Trust of India. It started operations in 1994 and has 729 branches with annual revenue of $2 billion.

9. Union Bank of India (BSE:532477). The Union Bank was created by Mahatma Gandhi and is one of India’s largest public-sector banks with around 3,025 ATMs and 27,750 employees. It has annual revenue of $3.4 billion.

8. Bank of India (BSE:BOI). It was founded in 1906 and now primarily provides mobile banking and online services. It has annual revenue of $3.9 billion.

7. IDBI Bank Limited (BSE:500116). Established by an act of parliament to help develop Indian industry, the bank has 1,500 ATMs and 900 branches with yearly revenue of $4.1 billion

6. Canara Bank (NSE:CANBK). The bank has revenues of $5.4 billion and was established in 1904.

5. Bank of Baroda (BSE:532134). The bank has 4,283 branches and more than 2,000 ATMs with annual revenue of $5.5 billion.

4. Punjab Bank of India (NSE:PNB). It was founded in 1894 and has more than 37 million customers. Yearly revenue is around $6.6 billion and it has 5,000 branches across 764 cities.

3. HDFC Bank (NYSE:HDB). Founded in 1904, it is considered one of India’s best banks. It has 1,500 branches and more than 3,000 ATMs. Its revenue is about $6.87 billion.

2. ICICI Bank (NYSE:IBN), India’s second-largest with more than $13.52 billion in revenue. It’s a globally recognized bank with branches all over the world and more than 1,400 in India alone.

1. State Bank of India (LSE:SBID). The bank is huge with more than 16,000 branches and 8,500 ATMs across India. And with revenue at $36.95 billion, it is easily India’s biggest bank.