The long-time friendship that existed between Rand and former Federal Reserve Chairman Alan Greenspan may be old news. But a lesser-known detail is that, despite financial guidance from Mr. Greenspan, Rand never invested her money in the stock market, says biographer Anne Heller, author of “Ayn Rand and the World She Made.” “The greatest proponent of capitalism was afraid to use the greatest mechanism of market capitalism.”

When Rand died in 1982, she left nearly $800,000 in her estate, much of which she kept in a savings bank across the street from her apartment, Ms. Heller says in a telephone interview. “She was a timid woman. Fierce as she was, she was also a little frightened.... She didn’t trust anything she didn’t understand, and she lived incredibly modestly.”

Time played a key role in Rand’s decision not to invest in the market. “To me, it was somewhat like not taking vitamins: that she’d have to do too much research herself to feel comfortable doing it,” Kathryn Eickhoff, Rand’s friend and later financial adviser, said in a 1999 interview.

“She didn’t want to invest because she was worried about the effects of government inflation and controls on the economy,” Harry Binswanger, a philosophy professor at the Ayn Rand Institute, says in a telephone interview.

“[A] dangerous collapse is inevitable," Rand said during a Q&A session after a 1965 lecture at Suffolk University in Boston. "What I wouldn’t care to guess is when. The situation is so precarious that it can be tomorrow or it may stretch a few more years,”

Through the encouragement of Ms. Eickhoff and other financial advisers, Rand eventually did invest in some special bonds. “These were a specific series of government bonds, which, while they were at the time selling at a discount from par because interest rates were high, in case of death they could be used at face value to settle estate taxes," Eickhoff said in the 1999 interview.