There are many advantages of having a large company over a smaller company.
As asked in the question, 2 main, of the many, advantages are described below.
Large companies are established companies. They usually have large number of stakeholders. So they are financially sound companies. They are usually not in threat of being bankrupt. And they have a greater access to funding.
Secondly, they can somehow lower their costs when they are having huge sales volumes. This cannot be done by smaller companies.