Alan Greenspan, the influential economist who steered U.S. monetary policy during his five terms as chairman of the Federal Reserve under four presidents, died Monday, his wife said in a statement.

He was 100.

Greenspan helped shape modern American capitalism from the final years of the Cold War era through the dawn of the digital age. He presided over the Fed during one of the longest economic expansions in U.S. history, a boom stretching from 1991 to 2001. But he was also faulted for decisions that critics say created the conditions for the global financial crisis of 2007-08, such as advocating for deregulation of the financial sector.

He is survived by his wife of 29 years, Andrea Mitchell, the chief Washington correspondent and chief foreign affairs correspondent for NBC News.

“Alan passed away at our home this morning at the age of 100 from complications of Parkinson’s Disease,” Mitchell said in a statement.

“He was a giant of a man who helped shape the U.S. economy for decades under presidents of both parties, but was always honest in acknowledging his mistakes,” she said.

“To me he was my husband, who shaped my life from our very first date in 1984. He had ‘irrational exuberance’ for baseball, the Washington Commanders, tennis, golf and music, especially jazz,” Mitchell added. “He will be remembered for his brilliance and his kindness. Being his life partner was the joy of my life.”

Greenspan was born on March 6, 1926, in the Washington Heights neighborhood of New York City, where he showed mathematical acumen from a young age. In his early years, he attended the Juilliard School and played jazz saxophone and clarinet in a band.

He studied economics at New York University, earning a bachelor’s degree in 1948 and a master’s in 1950, and then started work on a doctorate at Columbia University under economist Arthur F. Burns, a future chairman of the Federal Reserve.

In the early 1950s, Greenspan became an associate of the “Atlas Shrugged” writer Ayn Rand, whose “objectivist” philosophy of self-interest and laissez-faire capitalism inspired future generations of political libertarians and conservatives. Greenspan embraced some of her beliefs and paid tribute to her in his 2007 memoir.

“Ayn Rand and I remained close until she died in 1982, and I’m grateful for the influence she had on my life. I was intellectually limited until I met her,” Greenspan wrote in “The Age of Turbulence: Adventures in a New World.”

Greenspan departed Columbia in 1953 and joined an economic consulting firm that became known as Townsend-Greenspan Co., Inc. Five years later, he became president and chief owner of the firm.

Greenspan’s initial foray into the political world came in 1967 when he served as an adviser on Richard Nixon’s 1968 presidential campaign. Greenspan assisted with Nixon’s transition to the Oval Office but turned down an official role in the administration.

He advised Nixon on an informal basis and, following Nixon’s resignation in 1974, took a position in President Gerald Ford’s administration as chairman of the Council of Economic Advisers, serving until 1977. He pursued policies that, together with tighter monetary policy from the Paul Volcker-led Federal Reserve, helped reduce inflation from 11% to 6.5%.

In 1977, at the dawn of Jimmy Carter’s presidency, Greenspan returned to his consulting firm in New York and accepted an adjunct professorship at New York University, where he received a Ph.D. in economics.

Greenspan returned to government service when President Ronald Reagan appointed him to fill Volcker’s term as chairman of the Federal Reserve. Greenspan’s nomination was confirmed by the Senate on Aug. 11, 1987, during Reagan’s second term.

On Oct. 19, 1987, or “Black Monday,” when the Dow Jones Industrial Average plummeted by more than 22% — the blue-chip index’s largest one-day percentage fall ever — Greenspan moved swiftly to keep the markets liquid. From then on, Fed moves to support financial markets through episodes of instability became known as the “Greenspan put.”

He drew praise for steering the economy through what was then the longest expansion in U.S. history, running roughly from March 1991 to the first quarter of 2001, a transformative period that saw the acceleration of globalization and the rise of the internet. Greenspan navigated the Fed through seminal events, including the “dotcom” bubble burst and the aftermath of the Sept. 11 terror attacks in 2001.

He achieved celebrity status when stocks soared to record levels under President Bill Clinton. The writer Christopher Hitchens called him “America’s least-likely celebrity,” The Economist magazine dubbed him a “rock star,” and his admirers called him “the maestro.”

Greenspan, who served five consecutive four-year terms, retired on Jan. 31, 2006. He has the second-longest tenure as Fed chair, behind William McChesney Martin, who served from 1951 to 1970.

In the wake of the financial collapse of 2007-08, Greenspan drew scrutiny for decisions that some critics believe set the stage for the meltdown. Despite his infamous warning in 1996 that “irrational exuberance” was unduly inflating stock prices, Greenspan was faulted for missing the early 2000s housing bubble.

In 2011, the bipartisan Financial Crisis Inquiry Commission determined that the crisis was triggered in part by Greenspan’s failure to discourage trade in securities backed by subprime mortgage loans amid an unsustainable housing boom and his promotion of financial industry deregulation.

“More than 30 years of deregulation and reliance on self-regulation by financial institutions, championed by former Federal Reserve chairman Alan Greenspan and others, supported by successive administrations and Congresses, and actively pushed by the powerful financial industry at every turn, had stripped away key safeguards, which could have helped avoid catastrophe,” the report said in part.

In testimony to the House Committee on Oversight and Government Reform in October 2008, Greenspan referred to the financial crisis as a “once-in-a-century credit tsunami.”

“The crisis, however, has turned out to be much broader than anything I could have imagined,” Greenspan acknowledged.

After leaving the Fed, Greenspan started his own consulting company in Washington, and he authored several books.

He shared his impressions of the presidents he had worked with in his memoir “The Age of Turbulence” and in interviews. Nixon was smart but paranoid, he said. Ford “was a genuinely nice man who was not ruthlessly ambitious,” he said in a 2009 interview.

Reagan, the president who nominated him, “fervently believed in, and acted on, a small number of important principles,” he said in remarks at the Reagan Library in 2003.

Despite being a lifelong Republican, Greenspan had a strong relationship with Clinton, a Democrat, and praised his intelligence and fiscal discipline. Clinton, he joked, “was the best Republican president we’ve had in a while.”

His relationships with George H.W. Bush and George W. Bush were more complicated. The elder Bush blamed Greenspan publicly for the poor economy that likely contributed to his election loss, which Greenspan said in his book “surprised” him.

Greenspan said he was disappointed in the younger Bush for failing to rein in the budget with a GOP-controlled Congress, and that Republicans deserved it when they lost control of both chambers in the 2006 midterms. “The Republicans in Congress lost their way. They swapped principle for power. They ended up with neither,” he wrote in his book.

Greenspan’s successors as Fed chair include Ben Bernanke, Janet Yellen, Jerome Powell and, as of this May, Kevin Warsh, who was appointed by President Donald Trump.

Greenspan received various national and international accolades: In 2000, the French government awarded him the Legion of Honor; and in 2002, Queen Elizabeth II named him an honorary Knight of the British Empire. He was awarded the U.S.’s highest civilian honor, the Presidential Medal of Freedom, by then-President George W. Bush in 2005.