Investors were shocked today after industrial production from Europe's linchpin economy was revealed to have unexpectedly plunged again in December.



It's the second month in a row factory output in Germany has slowed, and suggests the country is suffering more heavily than initially thought from reduced demand for goods from China and emerging markets.



At the same time, Germany's top stock market the DAX, measuring the values of the country's biggest firms, has hit a two-year low.



The index fell by three per cent yesterday alone and is one of the worst performing stock markets in the world this year, after losing 14.5 per cent since the start of January.



Shares in Germany's biggest bank Deutsche Bank have dropped to lows not seen since 2009 at the height of the financial crisis, after plunging 40 per cent this year alone - showing the scale of trader's fears over the firm's stability.



Michael Hewson, chief market Analyst at CMC Markets UK, said: "We have Germany’s Deutsche Bank, whose shares have plunged to levels last seen in 2009 at the height of the financial crisis, and is down nearly 40 per cent this year alone, over concerns about the resilience of its balance sheet.



"The cost of insuring the German banks debt against default surged yesterday, as investors took fright, and as we know from Lehman Brothers, no matter how healthy a bank looks on the surface, sentiment can deteriorate very quickly."



The strength of Germany's economy is especially crucial for the stability of the eurozone, as many of the other member countries have still not fully recovered hits taken in 2009.



Greece, Spain and Italy are among those that continue to struggle under the burden of huge debts, while France is blighted with stagnant growth and high unemployment.



Eurozone growth is expected to come in at just 0.3 per cent for the final three months of 2015 in data later this week.