Is network marketing considered Haram?

Praise be to Allah, the Lord of the World; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
The financial markets nowadays are - most of the time - based on unlawful transactions or at least transactions that contain some unlawful matters. Above all those transactions, which are through the Internet, have a high probability of risk and lack of clarity in them and other Islamic prohibitions.
So, the Muslim who wants to enter these markets should be very careful and should make sure that all the transactions he makes are free from the Islamic prohibitions.
Allah knows best.