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The ShortDAX is a share index of the Deutsche Börse Group. It is designed to benefit from falling prices in Germany's largest stock index, the DAX , similar to a short position . To do this, it replicates the daily performance of the DAX in inverse proportion . H. the ShortDAX rises every day by the percentage that the DAX falls - and vice versa.

ETFs exist as a financial instrument for investing in the ShortDAX . This also enables investors to participate in falling prices who are not allowed to enter into short positions through futures contracts or use other leveraged instruments , e.g. B. some asset management companies or funds .

There are also leveraged short index products that show the daily change in the underlying value, for example twice or four times.

In the case of ShortDAX ETFs, losses are limited to the capital employed, and there is no obligation to make additional contributions, as is the case with short contracts on futures exchanges .

Index calculation and deviations from the base value

The ShortDAX tracks the daily return of the DAX with the opposite sign. If the DAX falls by 1% (corresponds to a return of −1%), the ShortDAX also rises by 1% on the same day.

However, the two indices do not develop in direct inverse proportion over time, but deviate somewhat from it. This is due to the methodology of daily adjustment. Because of the daily adjustment, the average daily performance after a period of x days does not correspond to the arithmetic mean , but instead to the geometric mean . This deviation is proportional to the daily changes, i.e. H. the greater the price fluctuations, the greater the deviation in the ShortDAX.

In practical terms, this means that the return on the ShortDAX is always slightly lower than the loss in the DAX or, conversely, that the loss in the ShortDAX is always slightly greater than the profit in the DAX. These deviations accumulate over time, so that a ShortDAX investment in a market that constantly fluctuates around the same price incurs losses, although the underlying is almost unchanged at the end of the period.

With the daily index adjustment, the absolute returns also increase the further the underlying falls. Conversely, the lower the absolute losses the further the base value rises.


Using a short example of the price fluctuations over two days, it can be shown how differently the two indices developed in the end.

An investor in the underlying, the DAX, comes back to the original amount at the end, because the bottom line has not moved the index. An investor in the ShortDAX, on the other hand, has to record a small loss.

Day Change in the DAX Index level DAX ShortDAX index level
0 0% 100,000 100,000
1 −5 (−5,000%) 095000 105000
2 +5 (5.263%) 100,000 099474
Return 0% −0.5263%

Calculation of the mean daily return using the geometric mean:

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