Hetty was a successful businesswoman who dealt mainly in real estate, invested in railroads and mines, and lent money while acquiring numerous mortgages. The City of New York came to Hetty for loans to keep the city afloat on several occasions. Estimates of her net worth ranged from $100 million to $200 million (equivalent to $2.49 billion to $4.98 billion in 2022), making her arguably the richest woman in the world at the time.