The stranglehold American technology companies have in the business world is something the European Union (EU) is not completely comfortable with.

In response, the union has created a program to strengthen European companies. One of its first tasks is to investigate the practices of American companies Apple, Facebook, Google and Amazon, according to CNN.

Reasons vary as to why each particular company is getting looked into.

With Apple, its European headquarters are based in Ireland. As CNN notes, the company has been accused of unfairly paying lower taxes in Europe thanks to a "deal" with the country where its HQ is. Another red flag to the EU is Apple's new music streaming service. The union is investigating if Apple did anything illegal to try and squash competitors.

Most of Facebook's users don't even understand the social media comapny's confusing privacy policies. That is what the EU is honing in on, particularly how Facebook track data to cater ads to users. 

According to CNN, Google controls "about 90%" of search engine usage in Europe. The EU is looking into how Google promotes content, especially its own. This is only the latest instance of the EU frowning upon the search engine giant's practices. Just last year it voted to break up Google in order to level out the playing field.

E-commerce titan Amazon is being investigated because of how it chooses to ship items across borders in Europe. CNN reports that EU's main issue is the difference products cost depending on which European country you are shipping it to.