Why might the lack of competition resulting from business mergers tend to lead to market failures

Mergers usually occur between two companies with complimentary business activities, who want to work together and dominate an industry.

These usually lead to oligopolies and in some cases, a monopoly over the market. This can lead to less choice for the end customer and even price hikes.

A lack of competition is never good for a market

Eventually too many jobs, businesses and third-party contractors work for a smaller number of companies and become exposed to market failures.