Why did chartered companies have private armies?

The chartered companies have private armies for protection.

Explanation:

The chartered companies have their armies and navies because of their occupations that led them to establish trading conduct outside their countries. They needed protection from people where they traded. They kept standing armies and forts to carrying out financial activities. Chartered companies were able to monopolize the markets, trade, slaves, extort tribute, seize land, and wealth to gain profits.