Johanna Quandt, German billionaire and heiress, passed away on Monday at her home in Bad Homburg at the age of 89.

The Quandt family holds a large stake in luxury car maker BMW AG, The Wall Street Journal reported. Her death was confirmed by a spokesman for Quandt's foundation on Wednesday.

Johanna met her late husband, industrialist Herbert Quandt, in the 1950s when she was hired as his secretary, then his personal assistant. Herbert would go on to save BMW from bankruptcy in 1959, according to Forbes. The couple married in 1960 and shared two children together, Stefan Quandt and Susanne Klatten. Herbert passed away in 1982, and Quandt took his seat on BMW's supervisory board.

"Johanna Quandt was a force within BMW for over 50 years and brought enthusiasm and passion to the company," BMW Chief Executive Harald Krüger said in a statement obtained by the WSJ.

Quandt owned about 17 percent of BMW at the time of her death. Together with her children, the Quandt family owns about 47 percent of BMW.

Quandt was Germany's second-richest woman, according to Fortune. During her life, she used her position of wealth to donate to causes that held the most importance to her. She had been a donor to Germany's big center-right party, Angela Merkel's Christian Democratic Union. She also donated to the smaller, pro-business Free Democrats. She was also generous to other causes like business journalism, the arts and healthcare research.