Mega mergers, also known as large-scale mergers and acquisitions (M&A), happen for several reasons. One of the main reasons is to achieve economies of scale. When two large companies merge, they can combine their resources, such as production facilities, distribution networks, and research and development capabilities, which can result in significant cost savings and operational efficiencies. This can help the merged company to become more competitive in the market, and increase profitability.

Another reason mega mergers happen is to achieve market dominance. When two large companies merge, they can create a dominant market player that controls a significant share of the market. This can lead to reduced competition and higher prices for consumers.

Mega mergers can also happen to diversify revenue streams. Companies that merge can take advantage of each other's strengths and capabilities to expand into new markets or diversify their product or service offerings. This can help to reduce risk and increase long-term stability for the merged company. When two huge companies merge together is paves the way for the companies to gain access to new technologies, intellectual property, and other valuable assets that can help the acquiring company to improve its competitiveness.

Lastly, mega mergers can happen to improve shareholder value. Shareholders of a company may see a merger as a way to increase the value of their investment, as the company can improve its profitability and long-term stability.

Hence, mega mergers happen for several reasons such as achieving economies of scale, achieving market dominance, diversifying revenue streams, gaining access to new technologies, and improving shareholder value. These factors can make a merger an attractive option for companies looking to expand their market share, reduce risk, and increase profitability. But these mega mergers can also raise concerns about potential anti-competitive effects. When the huge corporations or companies merge they posses a huge threat to the other companies either small scale or large scale dealing in the same line of business.

Anti-competition refers to actions or practices that restrict or reduce competition in a market, which can lead to higher prices, reduced innovation, and a lack of choice for consumers.

The primary concern with mega mergers is that they can lead to a reduction in the number of competitors in a market. When two large companies merge, it can create a dominant market player that controls a significant share of the market. This can lead to reduced competition and higher prices for consumers.

Mega mergers can also lead to a reduction in innovation. When a dominant market player controls a significant share of the market, they have less incentive to innovate and improve their products or services. This can lead to a lack of choice for consumers and reduced innovation overall.

Another concern with mega mergers is that they can lead to a lack of transparency and accountability. When a dominant market player controls a significant share of the market, they may have less incentive to disclose information about their business practices, which can lead to a lack of transparency and accountability.

The process of merger review is important to evaluate the potential effects of a merger on competition. The agencies who are responsible for this evaluation, such as the Federal Trade Commission (FTC) and the Department of Justice (DOJ) in the United States, will review the merger to determine if it is likely to result in anti-competitive effects. They will consider factors such as the market share of the companies involved, the degree of competition in the relevant market, and the potential for new entrants to the market.

However, it's worth noting that not all mega mergers are considered anti-competitive. Some mega mergers may result in significant cost savings and operational efficiencies that can be passed on to consumers in the form of lower prices. In addition, some mega mergers may be necessary to compete with larger, global companies.

In conclusion, mega mergers can raise concerns about potential anti-competitive effects, such as a reduction in the number of competitors in a market, a reduction in innovation, and a lack of transparency and accountability. It's important for the agencies responsible for merger review to thoroughly evaluate the potential effects of a merger on competition. However, not all mega mergers are considered anti-competitive, and some may result in benefits for consumers.