Stephen Bechtel Jr. is the co-owner and former chairman of Bechtel Corporation, with an estimated net worth of $3.4 billion as of April 2016, according to Forbes. He is 143rd in the “Forbes 400” list and is ranked 458th on the list of world billionaires.

Stephen D. Bechtel Jr. was born on May 10, 1925. He is the son of Stephen David Bechtel Sr. and the grandson of Bechtel Corporation founder Warren A. Bechtel. He attended Purdue University, where he earned a Bachelor of Science degree in civil engineering in 1946. He also earned an MBA from the Stanford Graduate School of Business in 1948.

A member of the third generation of the Bechtel family, Stephen Bechtel Jr. joined the family’s company right after completing his MBA. Since then, he has led the eponymous engineering and construction firm in several ventures. He became president In 1960 at the age of 35. He was named the chairman of the company, which is known for its large-scale projects such as the Hoover Dam, the Channel Tunnel, and Jubail, a city built from scratch in Saudi Arabia.

Stephen Jr. currently serves as a non-executive member of the board of directors. He retired in 1990, and his billionaire son Riley took over the company and now serves as the Chairman and Chief Executive Officer. In April, Bechtel invested an undisclosed sum in Planetary Resources, a company looking to mine near-Earth asteroids for raw materials, along with Google CEO Larry Page and Ross Perot Jr.

Stephen Bechtel Jr. is believed to own 20% of the private engineering and construction company with revenues of $37.9 billion in 2012. His foundation donated $50 million in 2009 to the Boy Scouts of America to help build a 10,600-acre reserve in West Virginia.