He is the Class of 1941 Professor of Economics, and past Chair of the Economics Department. He is currently on leave from MIT, as Economic Counsellor and Director of the Research Department of the International Monetary Fund.

He is a macroeconomist, who has worked on a wide set of issues, from the role of monetary policy, to the nature of speculative bubbles, to the nature of the labor market and the determinants of unemployment, to transition in former communist countries. In the process, he has worked with numerous countries and international organizations. He is the author of many books and articles, including two textbooks in macroeconomics, one at the graduate level with Stanley Fischer, one at the undergraduate level.

He is a fellow and Council member of the Econometric Society, a past vice president of the American Economic Association, and a member of the American Academy of Sciences.

From 2009 till earlier this year he served as a Counselor to Secretary Geithner working on range domestic financial issues. He also led the initial effort to establish the Treasury’s new Office of Financial Research. From 1999 till 2009 Mr. Alexander worked for Citigroup, first as the head of emerging market economics and later as Citi’s Chief Economist. Before joining Citigroup he worked for ten years in the Division of International Finance of the Federal Reserve Board, lastly as Deputy Director. From 1993 till 1996 he also served as Chief Economist of the U.S. Department of Commerce. Mr. Alexander has a Ph.D. in Economics from Yale University.

Previously he served at the US Federal Reserve Board as associate director, Division of International Finance (1999–2008), and senior economist (1987–1990 and 1991–97). He has also served at the US Treasury Department (1994–95 and 1997–1999) and has taught at the University of California's Haas School of Business (1990–91). He is author of Flexible Exchange Rates for a Stable World Economy (2011) and The Global Outlook for Government Debt over the Next 25 years: Implications for the Economy and Public Policy (2011). He has published numerous articles in economics journals, including the Journal of International Economics, the Journal of Monetary Economics, the Review of International Economics, and the Journal of International Money and Finance, and has contributed to several edited volumes. He received a BA from Harvard University in 1981 and a PhD in economics from Stanford University in 1987.

He received his Ph.D. in economics from Harvard University in 1984, and taught at the University of Pennsylvania's Wharton School as the W.P. Carey Assistant Professor of Finance from 1984 to 1987, and as the W.P. Carey Associate Professor of Finance from 1987 to 1988.

Williams, a Sacramento native, received a doctorate in economics from Stanford University, a master’s degree in economics with distinction from the London School of Economics, and a bachelor’s degree with high distinction in economics from the University of California at Berkeley.