Professor at UC Berkeley. Labor economics.

Joined May 2021
Alex Mas retweeted
With all eyes on the inflation statistics released this week, little attention was paid to the Treasury statement released on Friday. It showed the nation racked up a nearly $2 trillion budget deficit in just-ended fiscal year 2026. That’s more than 6% of GDP.
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Why Tylenol works is not fully understood.
This is a slide from Terence Tao's 'Math 2.0' public lecture yesterday evening at Caltech. I am highly confident that, if the cure actually worked, almost any Stage 4 cancer patient would tell you that human comprehension of its mechanism is completely irrelevant to them.
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It's an odd fact that the Spanish began exploring the California coast in 1542 and did not find the San Francisco Bay until 1769.
Spanish missionaries in California dedicate a small chapel by a large bay that they call the Mission San Francisco.
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Wealth is productive capital. It funds infrastructure, plants, technology, R&D, and employment. In the US the market allocates capital pretty efficiently. The income from this invested capital can be reinvested or (for the very wealthy) spent on expensive things like yachts and art. Taxing income reduces some of that consumption, which is completely defensible. Taxing wealth itself and you are disassembling the machine that makes the economy grow. That’s much harder to defend.
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Billionaire wealth does not sit idle. It is capital that funds innovation. CA wealth tax siphons that capital into a discretionary slush-fund for the state legislature.
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42 Nobel laureates in economics did not sign the letter endorsing the California billionaire tax.
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Hanno @HannoLustig is dead on. Proposition 40, which proposes to levy a ‘one off’ 5% wealth tax on billionaires, is ill conceived. Even if it raises the revenue its proponents claim for it, Proposition 40 will deter future startups from locating in California. It has already led to an exodus of top earners. The more serious effect is on the loss to California of future innovators that will locate in Florida or Texas. 💯👇
What puzzles me about French economists like Gabriel, as well as Emmanuel and Tomas, is the zeal they bring in trying to convince Americans that they have to implement a French model that is focused on redistribution rather than growth, because every indication we have suggests that the focus on redistribution has cost France, and some other countries in Europe, like my own native Belgium, very dearly so far. In fact, the French economy looks like it is about to enter a serious fiscal crisis because its redistribution model is no longer sustainable. Californians ought to celebrate the fact that wealth is being created in California, and not somewhere else in the U.S. or in the rest of the world. Americans, and Californians, for that matter, should continue to do what they do best, which is focus on growing the pie. It would be a mistake to adopt a model that is fundamentally broken. What the French should do instead is try to copy the model that made California an engine of innovation. In that case, smart, highly educated French kids wouldn't come to the U.S. to start companies. They would do so in France. If they had done that, they would have more than one AI startup company.
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Thinking today of all killed & injured at the Nova festival but particularly of Erick & Ruth Peretz. Ruth had cerebral palsy & learning disability & loved music so Erick her Dad would lift her from her chair & dance with her. When the terrorists came Erick was last seen running with Ruth in his arms. (Pictured here with Yamit Peretz who survived only as she had left the festival earlier.)
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Ariell Reshef and I have a new draft out. It is a paper about one figure. From 1850-1970 the employment share of legal services is constant. Between 1970-1990 it doubles, and then stabilizes at the new, higher, level. Lawyers' relative wages exhibit the same trend. What happened?
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But don't worry, the next gimmicky populist "soak the rich" tax will totally work
“LA’s ‘mansion tax,’ sold to Angelenos as a way to tax the rich and boost housing, has instead blocked the building of 9,100 homes, wiped out 16,650 full-time construction jobs and cost $452 million in revenue.”
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45 NBER WPs this week. Are we seeing the AI inflection in Econ?
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Talking to an Uber driving in SF about Waymo he says "I might have to look for another job" By contrast, talking to a taxi driver in Barcelona on the same topic his response was "it will be great! I will be able to make a living while watching TV at home."
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Fundamentals of Agentic AI, created by Professor Alex Mas and Pepe Alonso, MBA 27 and AI intern at Google, starts with the idea that  understanding AI requires students to look under the hood. #BerkeleyHaas #UCBerkeley newsroom.haas.berkeley.edu/h…
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