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Purpose – This paper aims to review the relevant literature on mergers and acquisitions in an attempt to provide a comprehensive account of what we know about mergers and which parts of the puzzle are still incomplete. Design/methodology/approach – This literature review consists of three key sections. The first part of this paper summarises the literature on the cyclical nature of mergers referred to in the literature as merger waves. The second section reviews the causes and consequences of takeovers; it first reviews the causes, or drivers, of acquisitions, while focusing on the fact that acquisitions happen in waves and then reviews the consequences of takeovers, with a predominant focus on the impacts of mergers on the economic performance of acquirers. The third part of the review summarises the theories as well as previous empirical studies on determinants of announcement returns and post-acquisition performance of combined firms. Findings – Merger activity demonstrates a wavy pattern, i.e. mergers are clustered in industries through time. The causes suggested for this fluctuating pattern include industry and economy-level shocks, mis-valuation and managerial herding. Market reaction to announcement of acquisitions is, on average, slightly negative for acquirer stocks and significantly positive for target stocks. The combined abnormal return is positive. These findings have been consistent over several decades of investigation. The prior research also identifies a number of factors that are related to performance of acquisitions. These factors are categorised and reviewed in five different groups: acquirer characteristics, target characteristics, bid characteristics, industry characteristics and macro-environment characteristics. Originality/value – This review illustrates a number of issues. Prior research is heavily biased towards gains to acquirers and factors that affect these gains. It is also biased towards finding sources of value creation through mergers, despite the fact that several theories suggest that mergers can be value-destroying. In fact, value destruction is often attributed to managers’ self-interest (agency problem) and mistakes (hubris). However, the mechanisms through which mergers destroy value are rarely addressed. Aside from that, the possibility of simultaneous creation and destruction of value in acquisitions is not often considered. Finally, after several decades of investigation, a key question is not completely answered yet: “What are the sources of value in mergers and acquisitions?”

Accuracy and speed of detection, along with technical and instrumental simplicity, are indispensable for the bacterial detection methods. Porous silicon (PSi) has unique optical and chemical properties which makes it a good candidate for biosensing applications. On the other hand, lectins have specific carbohydrate-binding properties and are inexpensive compared to popular antibodies. We propose a lectin-conjugated PSi-based biosensor for label-free and real-time detection of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by reflectometric interference Fourier transform spectroscopy (RIFTS). We modified meso-PSiO2 (10–40 nm pore diameter) with three lectins of ConA (Concanavalin A), WGA (Wheat Germ Agglutinin), and UEA (Ulex europaeus agglutinin) with various carbohydrate specificities, as bioreceptor. The results showed that ConA and WGA have the highest binding affinity for E. coli and S. aureus respectively and hence can effectively detect them. This was confirmed by 6.8% and 7.8% decrease in peak amplitude of fast Fourier transform (FFT) spectra (at 105 cells mL−1 concentration). A limit of detection (LOD) of about 103 cells mL−1 and a linear response range of 103 to 105 cells mL−1 were observed for both ConA-E. coli and WGA-S. aureus interaction platforms that are comparable to the other reports in the literature. Dissimilar response patterns among lectins can be attributed to the different bacterial cell wall structures. Further assessments were carried out by applying the biosensor for the detection of Klebsiella aerogenes and Bacillus subtilis bacteria. The overall obtained results reinforced the conjecture that the WGA and ConA have a stronger interaction with Gram-positive and Gram-negative bacteria, respectively. Therefore, it seems that specific lectins can be suggested for bacterial Gram-typing or even serotyping. These observations were confirmed by the principal component analysis (PCA) model.

Purpose This paper aims to review the relevant literature on mergers and acquisitions in an attempt to provide a comprehensive account of what we know about mergers and which parts of the puzzle are still incomplete. Design/methodology/approach This literature review consists of three key sections. The first part of this paper summarises the literature on the cyclical nature of mergers referred to in the literature as merger waves. The second section reviews the causes and consequences of takeovers; it first reviews the causes, or drivers, of acquisitions, while focusing on the fact that acquisitions happen in waves and then reviews the consequences of takeovers, with a predominant focus on the impacts of mergers on the economic performance of acquirers. The third part of the review summarises the theories, as well as previous empirical studies, on determinants of announcement returns and post-acquisition performance of combined firms. Findings Merger activity demonstrates a wavy pattern, i.e. mergers are clustered in industries through time. The causes suggested for this fluctuating pattern include industry- and economy-level shocks, mis-valuation and managerial herding. Market reaction to announcement of acquisitions is, on average, slightly negative for acquirer stocks and significantly positive for target stocks. The combined abnormal return is positive. These findings have been consistent over several decades of investigation. Prior research also identifies a number of factors that are related to performance of acquisitions. These factors are categorised and reviewed in five different groups: acquirer characteristics, target characteristics, bid characteristics, industry characteristics and macro-environment characteristics. Originality/value This review illustrates a number of issues. Prior research is heavily biased towards gains to acquirers and factors that affect these gains. It is also biased towards finding sources of value creation through mergers despite the fact that several theories suggest that mergers can be value-destroying. In fact, value destruction is often attributed to managers’ self-interest (agency problem) and mistakes (hubris). However, the mechanisms through which mergers destroy value are rarely addressed. Aside from that, the possibility of simultaneous creation and destruction of value in acquisitions is not often considered. Finally, after several decades of investigation, a key question is not completely answered yet: “What are the sources of value in mergers and acquisitions?”

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