The chart that shows just how much bank stocks are getting hammered

Banking stocks have lost around a quarter of their value since the start of the year

Shares in Deutsche Bank and Unicredit have been particularly hard hit as investors have lost confidence (Getty)

It's a bad time to be a bank.

Banking stocks have lost around a quarter of their value since the start of the year.

Some are now trading around lows not seen since the financial crisis. Shares in Deutsche Bank and Unicredit have been particularly hard hit as investors have lost confidence.

It took reports that Deutsche Bank was considering buying back some of its own bonds on Wednesday to scrape its share price off the floor.

But the extent of the losses suggests that something much bigger than a loss of confidence in one or two banks is going on.

1. Profits

If you thought you were finding it hard to make money from your savings with such stubbornly low interest rates, imagine how banks feel.

The difference between the rate at which banks borrow and lend money - also called the spread - has shrunk so much in the US and Europe that it is more difficult for banks to make profits trading money like they are supposed to.

Investors hoped interest rates might be on the way up again after the US Federal Reserve raised rates in December. But after stock markets took a nasty turn at the start of the year, all that talk about rising rates very swiftly ended.

That means tougher banking conditions for longer.

2. Restructuring

Many banks, HSBC and Deutsche Bank among them - are realising that the era of big banking is coming to an end.

These jack-of-all trade banks are now pulling back on decades worth of expansion programmes and working out where their specialisms lie.

That comes with the pain of cost cutting and job losses along the way. It's left some investors wondering about their value.

3. Capital

New rules to forcing bankers told more capital reserves against their trading books were introduced after the last financial crisis.

They were introduced to make sure that if banks did ever run into trouble again, they would have money on the books to fend for themselves.

But with profits harder and harder to come by, banks have found it difficult to meet those capital requirements. So much so that regulators decided to soften the new rules in Europe in January.

Banks are worried that the costs of implementing and fulfilling the requirements will make it harder for them to invest in profit-making activities.

4. Confidence

Banks tend to do well when other markets are doing well, simply because when markets are on the up, traders feel like investing and banks have work to do.

That means when investors are worrying that China's economy is slowing, or that the oil price is going to keep falling, bank stocks suffer too.