Answer:
He leveraged his position at the government for personal business.
Step-by-step explanation:
William M. Tweed is a former US Senator who's later on convicted for political corruption. Stealing around $200 million from Tax payers (this happened in 1877, so the value would be in Billions today)
He used his power and connection in order for his company to be involved in various construction projects. By the end of his time as a Senate, he gained the status as the third largest land-owner in New York City.
On top of that, he also used his position and connection to take ownership over a lot of large companies (such as Harlem Gas Light Company and Third Avenue Railway Company)