Final answer:
A corporate merger occurs when two formerly separate firms combine to become a single firm through an acquisition.
Step-by-step explanation:
A corporate merger occurs when two formerly separate firms combine to become a single firm. When one firm purchases another, it is called an acquisition. An acquisition may not look just like a merger, since the newly purchased firm may continue to operate under its former company name. Mergers can also be lateral, where two firms of similar sizes combine to become one. However, both mergers and acquisitions lead to two formerly separate firms operating under common ownership, and so they are commonly grouped together.