Alan Greenspan, who shaped American economic policy for nearly two decades as chairman of the US Federal Reserve, has died at the age of 100. His long tenure made him one of the most influential economic policymakers in modern US history.

Greenspan led the Federal Reserve from 1987 to 2006, serving under four presidents: Ronald Reagan, George H.W. Bush, Bill Clinton, and George W. Bush. During his time at the helm, the US economy experienced a significant period of growth, often referred to as the "Great Moderation."

He oversaw critical economic junctures, including the stock market crash of 1987, the dot-com bubble, and the early stages of the housing boom that preceded the 2008 financial crisis. Greenspan's approach often involved careful management of interest rates and a belief in the self-regulating nature of markets.

Despite presiding over years of prosperity, Greenspan faced considerable criticism in the aftermath of the 2008 financial crisis. Critics argued that his monetary policies and regulatory stance contributed to the build-up of excessive risk in the financial system. His views on deregulation and his perceived underestimation of the risks associated with subprime mortgages became subjects of intense scrutiny.

Before his influential role at the Federal Reserve, Greenspan was an economist and consultant. He founded the economic consulting firm Townsend-Greenspan & Co. and served on various government advisory boards. His economic philosophy was heavily influenced by Ayn Rand in his earlier years.

Greenspan's death marks the end of an era for economic policy. His legacy is complex, characterized by both periods of remarkable economic expansion and significant challenges that continue to be debated by economists and policymakers.

His leadership at the Fed coincided with major technological shifts, including the rise of the internet and the dot-com boom, which he navigated with a generally hands-off approach, allowing market forces to largely dictate outcomes.

The long-term implications of his policies on wealth inequality and financial stability remain subjects of ongoing analysis and discussion among economic historians and analysts.