Alan Greenspan, who chaired the Federal Reserve for more than 18 years across four presidential administrations and became the most recognizable central banker in modern history, died Monday at his home in Washington from complications of Parkinson’s disease. He was 100 years old. His death, confirmed by his wife of 29 years, NBC News correspondent Andrea Mitchell, closes the book on a figure whose words and decisions shaped American markets for nearly two decades and whose legacy continues to influence how investors and policymakers think about the role of the Fed today.