1.1.
Many firms consider M&A as an important part of their long-term strategy, since it allows to acquire market share, takeover technological innovations and achieve synergetic effects and therefore to improve financial performance. Often, M&A deals are done with an aim to achieve some competitive advantage, such as market share, innovative technologies, skilled workforce and others. For example, Lukas et al. (2019) studied M&A as strategy for entering the market. They reviewed 2 main strategies, comparing them with each other. First is to acquire large market player, taking a “big leap”. Second is setting proper M&A program in several steps, starting from acquisition of small firm. Concluding, authors state that the choice of strategy must be based on possible synergy of it.  In order to go in details, there were done analysis of theoretical views on types of M&A. In basic general review of mergers and acquisition activities types, Toguzova and Dzhioev provided such classification (2016): By type of integration (functional roles in market) Vertical Horizontal Conglomerate  Co-generic By state affiliation Domestic Cross-Border By the method of combining the potential: Corporate alliances Corporations By deal participants’ attitude to the merger Friendly  Hostile By the terms of mergers, acquisitions:  Mergers on parity terms Mergers not on parity terms Mergers with the formation of a new legal entity Acquisitions By the mechanism of mergers and acquisitions 6.1. Mergers and acquisitions involving all assets and liabilities of target company 6.2. Purchase of some or all of the assets of the target company 6.3. Purchase of company shares Accordingly, different authors studied aspects of M&A deals through mentioned lenses. For instance, there are some articles about horizontal and vertical M&A deals. Ardislamov and Kokoreva (2010) reviewed a lot of articles on the topic and came to a several conclusions. According to their statements, both horizontal and vertical M&A can bring synergy. In case of horizontal deals synergetic effects are mostly devoted to operational aspect, while diversification allows to get financial synergy. Authors state that there must be more researches in field of changing value of acquirers after M&A, since results of current articles are contradictory.  Effect of horizontal and vertical M&A often is measured by relatedness of target to the acquirer. Precisely, this relatedness depends on how industrial specialization of one company is close to another. For instance, Lasse B. Lien and Peter G. Klein found positive correlation between relatedness to acquire returns, basing mostly on SIC code. Other authors came to opposite findings. (Agrawal et al, 1992). This can be supported by the idea that usage of SIC codes as a source for the measure of relatedness can lead to bias. For instance, Richard P. Rumelt (1982) stated that there is significant variation between different SIC classes and that it is wrong to assume that difference between various is equal. As Yang et al. (2018) pointed out, this is crucial for researches about M&A in high tech industries, since many IT startups share same or close SIC code, even being significantly different. Moving to the idea of ecosystems, there can be stated that M&A for ecosystem can be considered as vertical deal for diversification.  Another important direction of studies about M&A is researches using lenses “domestic or cross-border” M&A. Scientists state that cross-border M&As positively effect on average acquirers’ domestic sales (Stiebale & Trax, 2011). Such deals can positively influence not only on acquirer but also on target firm, improving cash ﬂow proﬁtability and labor utilization (Fraser and Zhang, 2009). However, it is significant to mention that there can be bias in studies of this field. As Reynolds and Teerikangas (2016) revealed, in globalized economies purely domestic M&A deal is not possible. Furthermore, analysis of M&A deals in this research via lenses of “cross-border / domestic” is not needed, since there is viewed ecosystem building in Russia primarily. It can be firmly stated that there are both cross-border and domestic deals across the sample, but they are not the subject of interest in this research. In addition, some articles are devoted to the analysis of post-M&A performance according to the deal participants’ attitude to the merger. Cosh and Guest analyzed 64 hostile takeovers and 139 friendly takeovers (2001) and find out that hostile acquisitions positively effect on profitability and share returns, while friendly acquisitions do not improve profitability and negatively effect on share returns in long-term. Such results are partly supported by research of Alan Gregory (1997), who analyzed returns after 452 M&A deals and revealed that hostile acquirers typically have higher abnormal returns that friendly acquirers. Kennedy and Limmack (1996) analyzed 345 friendly and hostile acquisitions and revealed that both types lead to low positive result on abnormal returns in short term, but negative effect in long-term. There is another popular direction of M&A studies, beyond mentioned classification. Different authors examine phenomenon of serial acquirers and how such strategy effects on their financial performance. The results are ambiguous. For instance, Rovit and Lemire (2003) prove that strategy of serial M&A deals creates positive value. Oppositely, Fuller et al. (2002) state that returns to firms that acquire public targets statistically are significantly negative. Billett and Qian (2008) support such idea, stating that CEO of frequent acquirers can have self-attribution bias, and then M&A can negatively effect on performance of such companies.   
M&A deals are considered as an important part of their long-term strategy, which allows to purchase market share, takeover technological innovations and achieve synergetic effects. For example, Lukas et al. (2019) studied M&A as an important part of their short-term strategy. They reviewed 2 main stages, first of which is to purchare large market player, taking a “big leap”. Second is to set proper M&A program in several steps, starting from purchase of little company.