**1. Introduction and relevance of the topic**

The last global financial crisis was set-up by risky mortgage backed security loans and triggered by the default of the Lehman Brothers Holdings in September 2008. This marked the beginning of many policy measures and changes. While central banks around the world began to decrease interest rates in order to boost the economy, stock markets soared. At the same time, the internet is becoming more and more a medium for global interconnection due

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© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

to technological advancements across all industries. Not only more people connect to the internet every day, also devices actively communicate with one another, coined under the term "the internet of things". Moreover, recent initial public offerings of well-known internet companies such as Groupon, LinkedIn, Facebook, Alibaba Group Holding Limited and funding support programs in the United States, the European Union and China drive the interest of investors for lucrative opportunities.

When looking at the development of certain equity indices in the United States, Germany and China, the rates show record or close to record peaks as seen on **Figure 1**. For the Nasdaq Composite Index such rates were last seen during the dot-com bubble while the Deutscher Aktien Index 30 is almost twice as high as during the dot-com bubble and before the recent financial crisis of 2008. For the China Securities Index 300, the sources from the Bloomberg database even state price-to-earnings ratios as high as 220 times reported profits.

Bringing these circumstances into a global context, an artificial economic boost was created after the crisis that made equity indices soar—just like before the dot-com bubble. Hence, the question arises how the situation as of December 2015 is different if it is at all. Are there signs of an asset price bubble as some research argues [1, 2]?

The dot-com bubble is one of the most disputed bubbles that occurred in the last decades. Each bubble can be modelled according to some rules. Welfare analysis with empirical prediction is subject to examine [3]. Also, the pure statistical tests are suitable to describe bubble [4]. But alternative assessment can be provided by another angle of view on bubbles [5]. Moreover, market bubbles are related to market volatility in general [6].

**Figure 1.** Increase of indices' values across regions. Source: Own elaboration by the authors.
