Category: Economics
Trading with ChatGPT
In this paper, we use ChatGPT outages to provide early evidence on whether investors rely on generative artificial intelligence (GenAI) to perform professional tasks and the associated impact on stock price informativeness. We document a significant decline in stock trading volume during ChatGPT outages. The effect is stronger for firms with corporate news released immediately before or during the outages and for firms with higher ownership held by transient institutional investors. We then document declines in short-run price impact and return variance during the outage periods, consistent with reduced informed trading. Lastly, we document a positive effect of GenAI-assisted trading on long-run stock price informativeness. Overall, our findings indicate that a significant number of investors use ChatGPT in ways that influence their trading decisions and market outcomes. Future research can investigate the mechanisms underlying these GenAI effects and the potential risks of using GenAI for trading.
That is from a new paper by Qiang Cheng, Pengkai Lin, and Yue Zhao. Via the excellent Kevin Lewis.
David Beckworth on stablecoins and stability
A key reason for the global financial cycle, as outlined by Hélène Rey, is that many firms and financial institutions in developing countries borrow heavily in U.S. dollars while their revenues, assets, and cash flows are denominated in local currency. When the Fed tightens policy, the dollar appreciates, global financial conditions tighten, and these firms suddenly find themselves squeezed by rising dollar debt burdens and falling asset values. This balance sheet shock forces cutbacks and retrenchment. This is one of the key channels through which U.S. monetary policy spills over globally.
But what Rashad Ahmed noted in our dicussion is that if households and firms begin holding dollar assets via stablecoins—in addition to borrowing in dollars—they begin to build a natural hedge on their balance sheets. A stronger dollar no longer only increases liabilities; it also raises the value of their dollar assets, helping to offset the shock. In effect, stablecoins can act as a decentralized balance sheet stabilizer, muting one of the very mechanisms that drives global financial volatility.
Here is the full post, featuring also a podcast on the topic.
Why did air conditioning spread so fast in Mexico?
A common theme in the vast literature on climate change is the estimation of models using historical data to make predictions many decades into the future. Although there is a large and growing number of these types of studies, researchers rarely return later to check the accuracy of their predictions. In this paper, we perform such an exercise. In Davis and Gertler (2015), we used household-level microdata from Mexico to predict future air conditioning adoption as a function of income and temperature. Revisiting these predictions with 12 years of additional data, we find that air conditioning in Mexico has accelerated, significantly exceeding our predictions. Neither errors in predicting income growth or rising temperatures, nor migration patterns, nor an overly restrictive model can explain the large prediction gap. Instead, our results point to the failure to account for falling electricity prices and technological changes in air conditioner efficiency as key drivers of the prediction gap.
That is from a new NBER working paper by Lucas W. Davis and Paul Gertler. As of 2022, the rate of air conditioning access in Mexico was about 18.5%, only slightly less than that of Europe.
The Rising Returns to R&D: Ideas Are not Getting Harder to Find (one hypothesis)
R&D investment has grown robustly, yet aggregate productivity growth has stagnated. Is this because “ideas are getting harder to find”? This paper uses micro-data from the US Census Bureau to explore the relationship between R&D and productivity in the manufacturing sector from 1976 to 2018. We find that both the elasticity of output (TFP) with respect to R&D and the marginal returns to R&D have risen sharply. Exploring factors affecting returns, we conclude that R&D obsolescence rates must have risen. Using a novel estimation approach, we find consistent evidence of sharply rising technological rivalry and obsolescence. These findings suggest that R&D has become more effective at finding productivity-enhancing ideas, but these ideas may also render rivals’ technologies obsolete, making innovations more transient. Because of obsolescence, rising R&D does not necessarily mean rising aggregate productivity growth.
Here is the paper by Yoshiki Ando (Singapore Management University, TPRI), James Bessen (BU, TPRI), and Xiupeng Wang. Via Arjun.
Transitory vs. permanent tariffs
We estimate transitory and permanent import tariff shocks in the United States over the postwar period. We find that transitory tariff increases are neither inflationary nor contractionary, and are not associated with monetary tightening. In contrast, permanent tariff increases trigger a temporary rise in inflation (a one-off increase in the price level) and a brief tightening of monetary policy. Consistent with the intertemporal approach to the balance of payments, transitory tariff increases reduce imports and improve the trade balance, whereas permanent increases leave both largely unchanged. Transitory shocks account for approximately 80 percent of tariff movements. Overall, tariff shocks are estimated to be a minor driver of U.S. business cycle fluctuations on average and even during episodes of substantial tariff hikes, such as Nixon 1971, Ford 1975, and Trump 2018.
Policy-relevant! That is from a new NBER working paper by Stephanie Schmitt-Grohé and Martín Uribe. Via Moses Sternstein.
Why Tariffs On More Countries Can Be Better
Today, I am going to explain why tariffs on more countries can be better! Not to worry, I still think free trade is the best policy (modulo some special cases discussed in Modern Principles) but I am going to show that a uniform tariff can be better than a selective tariff. My example comes from a nice tweet from Malaysia expert Apurva Sanghi, modified for the US context.
Suppose the U.S. can import Hyundai Sonatas from Korea and Toyota Camrys from Japan, and consumers view the two cars as perfect substitutes. We compare three scenarios:
A) Free trade
B) 10% tariff on both countries (uniform tariff)
C) 10% tariff on Korea only (selective tariff)
The surprising result: B can be better than C, even though C is, in one sense, closer to free trade (the “best” policy) than B as it tariffs fewer countries. To focus on the key points I will assume 50 car buyers and no change in the number of buyers when tariffs change (so I will ignore the standard deadweight loss from reduced quantities).
Assumptions
Korea (Hyundai Sonata): $40k pre-tariff
Japan (Toyota Camry): $43k pre-tariff
50 buyers; perfect substitutes
A) Baseline (free trade)
Everyone buys Sonatas from Korea at $40k.
U.S. tariff revenue: $0.
B) Uniform 10% tariff on all countries
Sonata: $40k → $44k
Camry: $43k → $47.3k
Consumers buy Sonatas from Korea (lowest-cost source preserved).
Per car: consumers pay +$4k; government gets +$4k.
Totals (50 cars):
Consumer loss: $200k
Tariff revenue: $200k
Total losses (national): ≈ $0 (consumers transfer $ to government; ignoring DWL from Q changes).
C) Selective 10% tariff (on Korea only)
Sonata (Korea): $40k → $44k
Camry (Japan): $43k (untaxed)
Buyers switch to Camry’s from Japan (trade diversion).
Totals (50 cars):
Consumer loss: 150k (consumers now pay $43k vs $40k in the no tariff baseline → $3k more per car)
Tariff revenue: $0 (imports shifted to untaxed Japan).
Net (national): –$150k.
Global efficiency: production cost rises from $40k → $43k per car → $150k real resource loss.
Total losses: 150k (consumer loss = real resource loss)
The total losses under scenario C in which just some countries are tariffed are larger than in scenario B in which all countries are tariffed! What’s going on? Under a uniform tariff, the lowest-cost supplier still wins. Tariffs create distortions, but a uniform tariff at least preserves efficient sourcing and generates government revenue. Under a selective tariff, sourcing can shift to a higher-cost supplier purely because of the tariff. That’s trade diversion —bad for efficiency which means some combination of consumers and government must lose.
Here’s an analogy. Forget tariffs for a moment and imagine taxing GM but not Ford. That could make Ford win sales even if GM can produce the same car more cheaply — an obvious waste. The same logic applies in international trade.
In general, as Brian Albrecht argues, tariffs are a costly way to raise revenue. Selective tariffs are especially inefficient and wasteful. Sad to say, the U.S. tariff system today is highly selective — wildly different rates on different countries and times. Trade diversion isn’t a necessary consequence of selective tariffs but our current high and chaotic tariff structure makes it all but inevitable. Thus selective tariffs mean standard deadweight losses will compound with large-scale trade diversion and inefficiency, raising losses above headline numbers. Finally, the selective structure invites rent seeking, as firms and industries lobby for favorable treatment — adding yet another layer of economic waste.
Addendum: Thanks to KarterB in the comments for correcting a calculation.
Is anyone worth a billion dollars?
That is the topic of my latest Free Press column. Excerpt:
…in recent years they [Meta] have moved into AI in a big way. Over that same time period, the valuation of the company has risen from about $236 billion in November 2022 to almost $2 trillion at the end of this July.
The reasons for share price movements are not always transparent, but it is common consensus that AI investments are a significant reason why Meta is now worth much more. The original metaverse plans did not take off, and Facebook and Instagram are relatively mature products and they have not changed much as of late.
So the market, responding to Meta’s promises about AI, expects that it will deliver on that $2 trillion value. Yet their current Llama models are not state of the art. Meta needs something better and more competitive.
Meta thus has to justify an extra $1.8 trillion in its valuation, which of course they could lose if markets decide they are not up to the task. Spending some billions on top-quality AI personnel is easy to justify when viewed in terms of the value gain Meta already has been reaping.
And it is not just about justifying the current $2 trillion valuation. Meta possibly could be worth more yet. It probably has not escaped their attention that as of late, both Nvidia and Microsoft have had valuations of about $4 trillion. So the possibility of further upside enters the equation as well.
Keep in mind that better AI also will boost the profits Meta can receive from ads on Facebook and Instagram. Click-through rates on ads typically are small, so even a modest increase in targeting ability can mean a lot more profit. Meta does not have to achieve superintelligence to get its money back on these investments; they just need better AI. There is also a plan to put more ads on WhatsApp (currently the user experience is mostly ad-free), and that too can benefit from better AI and better ad targeting.
The general principle is that top talent is typically undervalued, if only because of egalitarian norms in pay structures.
Did the Minnesota housing reform lower housing costs?
Yes:
In December 2018, Minneapolis became the first U.S. city to eliminate single-family zoning through the Minneapolis 2040 Plan, a landmark reform with a central focus on improving housing affordability. This paper estimates the effect of the Minneapolis 2040 Plan on home values and rental prices. Using a synthetic control approach we find that the reform lowered housing cost growth in the five years following implementation: home prices were 16% to 34% lower, while rents were 17.5% to 34% lower relative to a counterfactual Minneapolis constructed from similar metro areas. Placebo tests document these housing cost trajectories were the lowest of 83 donor cities (p=0.012). The results remain consistent and robust to a series of subset analyses and controls. We explore the possible mechanism of these impacts and find that the reform did not trigger a construction boom or an immediate increase in the housing supply. Instead, the observed price reductions appear to stem from a softening of housing demand, likely driven by altered expectations about the housing market.
That is from a new paper by Helena Gu and David Munro. Via the excellent Kevin Lewis.
The Sri Lankan economic recovery (from my email)
Hi,
I’m a macroconsultant/analyst based in Sri Lanka. Was suddenly reminded of your 2023 MR piece on Sri Lanka – soon after the depth of the crisis locally.
Since then, Sri Lanka has seen what I think to many is a remarkable turnaround on both the macro fundamentals and the social indicators (admittedly data is very divergent on social).
A few specific points on the macro –
– 2 years of twin surpluses (after 70+ years of twin deficits)
– Looks in line to do a 3rd year of twin surpluses alongside 5% growth
– Income tax collections growing 20%+ YoY without any text increases
– 4% of GDP in net government LCY balances vs historic deficits
– Gross capital formation rising dramatically without government capex spending
– Credit recovery without government spending to support private income
– Remittances (possibly cyclical), oil imports (massive distributed solar), and net port services (ME diversion+new capacity) overperforming IMF numbers by 1-2% of GDP
– Net foreign assets of banking system at ~2% of GDP
– Currency appreciated and stable from crisis peaks
– Inflation averaging 0% 3 years after crisis (+ energy driven deflation spots)
TC again: thanks to Chayu Damsinghe from Frontier Research. A true reversal of fortune, at least for the time being…
Peter Temin, RIP…
Alas…one of the greats in economic history…
Regulatory Complexity and Rents
Luis Garicano on the EU-US trade deal.
…The growing regulatory complexity and arbitrariness of the tariff regime provides rents to those connected with power, not to innovators. It is a recipe for the biggest enemy of growth: regulatory overkill and crony capitalism. Consider the example of importing a can of beer from Belgium into the US. There is a 10% country-specific tariff on the entire value of the product. On top of this, the aluminium can itself is treated as a completely separate product, subject to its own additional tariff of up to 50%. The level of this tariff is based on the nearly untraceable origin of the raw metal—the country where the aluminium was “smelted and cast.” The tariff rises to 200% if the country is unknown. This forces an importer to research the obscure global supply chain of a minor component and apply multiple, overlapping tax rates to a single, everyday item.
Many other interesting comments.
Genius, Rejected: Emergent Ventures Versus the System
Quanta Magazine has a good piece on a 17-year-old student who disproved a long-standing conjecture in harmonic analysis:
Yet a paper posted on February 10(opens a new tab) left the math world by turns stunned, delighted and ready to welcome a bold new talent into its midst. Its author was Hannah Cairo(opens a new tab), just 17 at the time. She had solved a 40-year-old mystery about how functions behave, called the Mizohata-Takeuchi conjecture.
“We were all shocked, absolutely. I don’t remember ever seeing anything like that,” said Itamar Oliveira (opens aof the University of Birmingham, who has spent the past two years trying to prove that the conjecture was true. In her paper, Cairo showed that it’s false. The result defies mathematicians’ usual intuitions about what functions can and cannot do.
…The proof, and its unlikely author, have energized the math community since Cairo posted it in February. “I was absolutely, ‘Wow.’ This has been my favorite problem for nigh on 40 years, and I was completely blown away,” Carbery said.
Here is the abstract to the paper:
I can’t speak to the mathematics but this is Quanta Magazine not People Magazine and Cairo is not coming out of nowhere. As the article discusses, she has been taking graduate classes in mathematics at Berkeley from people like Ruixiang Zhang. So what is the problem?
I was enraged by the following:
After completing the proof, she decided to apply straight to graduate school, skipping college (and a high school diploma) altogether. As she saw it, she was already living the life of a graduate student. Cairo applied to 10 graduate programs. Six rejected her because she didn’t have a college degree. Two admitted her, but then higher-ups in those universities’ administrations overrode those decisions.
Only the University of Maryland and Johns Hopkins University were willing to welcome her straight into a doctoral program.
Kudos to UMD and JHU! But what is going on at those other universities?!! Their sole mission is to identify and nurture talent. They have armies of admissions staff and tout their “holistic” approach to recognizing creativity and intellectual promise even when it follows an unconventional path. Yet they can’t make room for a genius who has been vetted by some of the top mathematicians in the world? This is institutional failure.
We saw similar failures during COVID: researchers at Yale’s School of Public Health, working on new tests, couldn’t get funding from their own billion-dollar institution and would have stalled without Tyler’s Fast Grants. But the problem isn’t just speed. Emergent Ventures isn’t about speed but about discovering talent. If you wonder why EV has been so successful look to Tyler and people like Shruti Rajagopalan and to the noble funders but look also to the fact that their competitors are so bureaucratic that they can’t recognize talent even when it is thrust upon them.
It’s a very good thing EV exists. But you know your city is broken when you need Batman to fight crime. EV will have truly succeeded when the rest of the system is inspired into raising its game.
Why the tariffs are bad
I am delighted to see this excellent analysis in the NYT:
Mr. Tedeschi said that future leaders in Washington, whether Republican or Democrat, may be hesitant to roll back the tariffs if that would mean a further addition to the federal debt load, which is already raising alarms on Wall Street. And replacing the tariff revenue with another type of tax increase would require Congress to act, while the tariffs would be a legacy decision made by a previous president.
“Congress may not be excited about taking such a politically risky vote when they didn’t have to vote on tariffs in the first place,” Mr. Tedeschi said.
Some in Washington are already starting to think about how they could spend the tariff revenue. Mr. Trump recently floated the possibility of sending Americans a cash rebate for the tariffs, and Senator Josh Hawley, Republican of Missouri, recently introduced legislation to send $600 to many Americans. “We have so much money coming in, we’re thinking about a little rebate, but the big thing we want to do is pay down debt,” Mr. Trump said last month of the tariffs.
Democrats, once they return to power, may face a similar temptation to use the tariff revenue to fund a new social program, especially if raising taxes in Congress proves as challenging as it has in the past. As it is, Democrats have been divided over tariffs. Maintaining the status quo may be an easier political option than changing trade policy.
“That’s a hefty chunk of change,” Tyson Brody, a Democratic strategist, said of the tariffs. “The way that Democrats are starting to think about it is not that ‘these will be impossible to withdraw.’ It’s: ‘Oh look, there’s now going to be a large pot of money to use and reprogram.’”
That is from Andrew Duehren, bravo.
Time Theft at the Terminal
Travel expert Gary Leff on the billions in wasted time spent at airports:
Maybe the biggest failure in air travel is something we don’t talk about at all. How is it possible that people are being told to show up at the airport 2.5 to 3 hours before their flight, and that isn’t considered a failure of massive proportions?
As Gary points out airport delay wipes out many technological advancements:
The lengthened times for showing up at the airport mean that it no longer even makes sense for many people to take shorter flights, but aircraft technology (electric, short and vertical takeoff) is changing and becoming far more viable in the coming years…The FAA is considering standards for vertiports but are we thinking creatively enough or will that conversation be too status quo-focused either because of regulator bias or because it’s entrenched interests most involved?
More and smaller airports are needed. Streamlined security, that doesn’t wait for nationwide universal rollout, is needed. We need runways and taxiways and air traffic capacity to increase throughput without stacking delays. Most of all, we need to avoid complacency that accepts the status quo as given.
By the way, Washington Dulles (IAD) has ~10.5 min security waits, among the best in the nation and the world for a big airport but it is terrible at inbound passport control. (Also, I am not a fan of the people movers.)
The economics of the U.S. auto industry, a brief history
The economic value of the cars being made has climbed substantially through the years. As a result, real value added and industrial production — two different ways of measuring actual output — are now at all-time highs.
And this:
What about jobs? The auto industry today employs 1 million workers. Between 1950 and the signing of NAFTA in 1993, it averaged 1.1 million workers, just slightly higher.
And this:
The deindustrialization of Detroit is typically understood as a phenomenon of the 1970s and 1980s, and it is therefore blamed on the growth of trade during this period. But the fact is that auto investment and employment had started moving out of Detroit decades earlier.
I pieced together data from a variety of sources, which shows that auto manufacturing employment in the City of Detroit had already peaked in 1950, at just over 220,000 workers.
By 1970 the biggest declines had already occurred, with employment falling by more than half, to fewer than 100,000 jobs.
An important nuance is that many of these lost jobs migrated to other parts of Michigan, at least for a while. So while auto employment was collapsing in Detroit, the rest of Michigan managed to hold auto employment stable for another five decades until the 2000s, when it started falling everywhere in the state.
And:
Michigan now has about 280,000 fewer auto jobs than it did in the 1950s, a decline of roughly 60 percent. For the United States as a whole, auto employment is only down 4.7 percent — further showing that the struggles of Detroit and Michigan are less about the decline of the American auto industry and more about its relocation elsewhere.
Another way of understanding the trend: If Michigan had simply maintained the same share of American auto jobs as it had in the 1950s, meaning it did not lose any production to other states, then it would only have lost 21,000 auto jobs since then, not the 280,000 it actually did lose.
An excellent piece, recommended.