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I really enjoyed talking to @benjaminfelix and @MarkMcGrathCFP about financial planning using the lifecycle model of economics vs SWR.
I’ve listened to the podcast for years and it was a privilege to be on the other side discussing a topic that’s close to my heart!
Episode 340 - Ben Mathew: The Lifecycle Model vs. Safe Withdrawal Rates (SWR)
rationalreminder.ca/podcast/…
A DIVERSIFICATION BLAST FROM THE PAST
Diversification does not protect you from a risk-asset crash risk. Regardless of how diversified you are, the risk-asset beta will cause all of your diversified or undiversified risk assets to crash simultaneously. The only way to protect yourself from the crash is simply have less overall risk-asset beta. Low leverage, cash and government bonds, etc.
Diversification _DOES_ protect you from lost decades. If you were in 100% in US large-cap equities vs. diversified into international equities/real-estate/small cap starting year 2000, you did a lot better being diversified. This is because the US large-cap equities had a "lost decade". The cause of the lost decade was that they were priced too high in year 2000.
If the objective is to avoid being hurt by poor 10-year returns of some asset classes, surely then one should also pay attention to valuations! Valuations are the only known way to forecast 10-year returns a little bit. Therefore, instead of just diversifying, one should also actively overweight cheap asset classes and underweight expensive asset classes. Not recklessly, but a little bit.
I think that international diversification isn’t so much about protection against crash risk. All markets crash together these days.
It’s mostly protection against a home country asset “lost decade” after an asset price bubble.
If you were able to diversify away from Japanese stocks in 1990, US stocks in year 2020, or developed market bonds in 2021, for example, that international diversification would have really helped your terminal wealth.
In my mind, international diversification becomes fantastically beneficial when it is combined with the ability (skill, temperament) to exclude assets priced to silly levels from the portfolio.
Ben Mathew retweeted
Rebuild buffers, reduce debt, and get your house in order. A good advice for economies but also household balance sheets.
The world economy has been resilient, but that resilience is getting depleted. My advice to our members: rebuild buffers, reduce debt, and get your house in order. Watch the full #IMFMeetings Global Debate:
imf.org/en/meetings/2026/ann…
Ben Mathew retweeted
Self-reported retirement income security, from the 2025 Survey of Consumer Finances.
Since 1992, there's been a dramatic reduction in the share of retirees reporting very low incomes and a similarly dramatic increase in seniors saying they are financially comfortable.
In 2025, 74% of seniors said they could at least maintain their pre-retirement standard of living, versus 61% in 1992.
On online gambling in Brazil:
“If gambling were a virus, we could call it a pandemic,” said Dr. Hermano Tavares, a psychiatrist who runs the clinic.
Gift article: nytimes.com/2026/10/01/world…
Ben Mathew retweeted
What on earth. These accounts got very weird very quickly. 👇
New from us:
Last week's Trump Accounts changes mean that millions of kids will get individual stocks that they can't reject and can't sell for five years.
wsj.com/politics/policy/trum…
Ben Mathew retweeted
Private credit is the return of shadow banking: opaque loans, stale marks, and heavy datacenter exposure. If AI wobbles, retail funds promising liquidity against illiquid loans may trigger a nasty run.
Yes. One of the biggest mistakes people make in investing is focusing on recent returns instead of yields and expected returns. Bond price drop = higher interest rate = higher expected return on bonds.
Replying to @Rick_Ferri
Exactly. Meanwhile, many of the same “experts” are now running from bonds based on past returns….
and ignoring the incredible yields now on offer and not seen in 20 years
especially for TIPS
Ben Mathew retweeted
The number of self-proclaimed bond experts who have come out of the closet to tell us we shouldn’t have owned bonds this year is unprecedented.
My question is this: If they are the interest rate geniuses they claim to be, why were they all silent at the beginning of the year?
Ben Mathew retweeted
Everyone, you should totally ask AI how much a 17 basis point increase on a $40 Trillion debt costs each year, then divide that number by 341 million Americans.
The number is right about $198 per person per year.
That's just from today folks. Just today.
Ben Mathew retweeted
In my last two posts, I emphasized the enormous gains in material wealth and life expectancy that humanity has experienced over the past couple of centuries.
But those improvements are nothing compared with the monumental gains in what I call moral autonomy and self-determination. Two centuries ago, in 1826, the vast majority of people were far less free and far less able to shape their own futures or their communities’ futures.
Let me start with labor. One striking feature of economic history is that, for most of the human past, much labor has not been free but coerced through violence, ranging from the worst forms of chattel slavery to serfdom, peonage, and feudal tenancy. In 1826, for example, around 30% of workers worldwide were subject to some form of violent coercion and to legal limits on the work they may do (this is different from, and more restrictive than, economic limits, such as being a landless laborer with little choice of employer). If you are born in 1826, you stand a strong chance of being born to an enslaved mother in the Americas or to a serf in Russia. Today, the ILO computes that fewer than 1% of workers are coerced in this way.
Let me continue with gender. If you are a woman in 1826, your freedom to choose a husband, an education, an occupation, how many children to have, and to own property is severely limited nearly everywhere. If you are an enslaved or coerced woman, you face a very high chance of sexual assault during your lifetime. Free women suffer these attacks too, with next to no recourse.
Let me move to religion and ideology. If you belong to the “wrong” religion, denomination, or ideology, or if you simply love someone you “should not love,” you risk severe punishment. Even in the U.S., Massachusetts still has an established church and will keep it until 1833 (the First Amendment applied only to the federal government until Everson v. Board of Education, 330 U.S. 1 (1947)). In the U.K., we are three years away from the Roman Catholic Relief Act of 1829 and forty-five years away from the abolition of religious tests at Oxford and Cambridge.
In education and culture, 88% of people are illiterate, and fewer than 2% hold the equivalent of a high school degree. For most, the great works of art and literature play no part in daily life, beyond perhaps a religious image or text seen in the local temple.
Finally, almost nobody outside a small elite participates in political life. In 1826, only the U.S. can be called a democracy, and that stretches the word. With very few exceptions, only white adult men can vote, and even among them, several states, such as Virginia, restrict the franchise to about 50% of white adult males. Some Swiss cantons (but not all!) do better, and Norway, then in union with Sweden, has a relatively broad franchise for men. The United Kingdom (before the 1832 reform), France, and the Netherlands have very restricted franchises. And that is pretty much it. Nothing resembling democracy or the rule of law exists in all of Asia and Africa, most of the Americas, and the rest of Europe. In nearly all the world, you could be arrested at the whim of your ruler, and there was little you could do about it.
I do not want to paint too rosy a picture of 2026. Workers are still coerced. Gender inequalities remain large. In many parts of the world, you still cannot think what you want to think or choose your own romantic life. Democracy has badly backslid over the last two decades. And I am increasingly forced to remind people that due process is the twin sister of liberty.
But if I ask you, behind a veil of ignorance, whether you want to live in 1826 or 2026 (that is, you do not know whether you will be born a king or an enslaved woman, only that the probabilities match the proportions in the global population), you would be crazy to pick 1826. Your life will be short. You will probably be very poor. You will be illiterate, told what to do for a living, who to pray to, and whom to marry, and no one will give a penny for your input into the running of your community. And, you can be arrested at will.
And this absence of moral autonomy and self-determination is worth ten, one hundred, or even one thousand times more than all the extra income that modern economic growth has given you.
My post on life spans:
xitter.cf/JesusFerna7026/status/…
My post on prosperity:
xitter.cf/JesusFerna7026/status/…
In 2028, the median person on Earth will live on more than $10 a day for the first time in history (figures adjusted for inflation and for differences in purchasing power across countries).
In the last decade alone, the share of people above this threshold has risen from 41.3% in 2016 (3.11 billion) to 48.7% in 2026 (4.03 billion). Think about that for a second: we have pushed nearly 900 million people over this threshold in ten years, around 90 million people a year (slightly above the population of Turkey).
At the very bottom, we have also seen progress, though slower. In 2016, 12.6% of the world lived below $3 a day (947 million people). In 2026, the figure fell to 10.0% (826 million). This fall is harder to achieve because the poorest countries also have fast population growth. As fertility falls there, and I think it is already falling, we will cut poverty much faster.
You are probably thinking that $10 a day is not a demanding threshold. True. But in 1990, yesterday in historical terms, only 1.42 billion people lived above it. And this is not just China: 2.6 billion people have crossed the $10 line. On the other hand, in 1990, 2.20 billion people lived below $3 a day.
I checked these figures today because I start teaching Global Economic History at Penn this Wednesday, and I wanted to update the numbers I use. As Joel Mokyr instructs us:
“The responsibility of economic historians is to remind the world what things were like before 1800. Growth was imperceptibly slow, and the vast bulk of the population was so poor that a harvest failure would kill millions. Almost half the babies born died before reaching age 5, and those who made it to adulthood were often stunted, ill and illiterate.”
(“What Today's Economic Gloomsayers Are Missing,” 2014.)
This will be my first lesson to the students on Wednesday: we live in times of historically unprecedented prosperity, and, by and large, things are getting much better every year.
The Coase theorem does good things. The Chaos theorem does bad things.
I'm super excited for my new paper with @ATabarrok and Mark Whitmeyer:
"Chaos and Misallocation under Price Controls"
During the 1973-74 gasoline crisis, the U.S. had about a 9 percent national shortfall. But that was far from evenly spread out.
Over 90 percent of stations in Connecticut were rationing fuel somehow, limiting purchase or straight up closed.
In Idaho, Montana, Utah, and Wyoming? Not a single surveyed station reported any problem. Zero. Texas and the Great Plains were "virtually awash with gasoline."
How does a 9 percent shortfall produce 90 percent rationing in one state and zero in another? And how big of a deal is that misallocation?
Our paper does three things.
First, we prove a Chaos Theorem: price controls generically push allocations to corners where some markets get everything and others get nothing, and which corner the economy lands on is unpredictable.
Second, we develop a new way to find sharp robust bounds on the welfare cost of this misallocation. Price controls destroy the demand information you'd need for standard welfare analysis, so we bound the losses across all demand curves consistent with the data. Sharp bounds.
Third, we apply both to the 1973-74 crisis and show that misallocation losses are 1 to 9 times the textbook Harberger triangle.
Let's go through each.
Why do price controls cause chaos?
Price controls kill arbitrage. Normally, if gasoline is scarcer in Connecticut than Idaho, the price rises in Connecticut, attracting supply eastward. A small cost advantage captures only a marginal reallocation, because prices push back.
Freeze the price everywhere and that pushback disappears. The supplier's problem reduces to pure cost minimization. Thinking of the geometry, cost is linear in quantity. A linear objective over a feasible set with corners always lands on a corner. This is the old idea, as Thomas Sowell put it, that economy loses its capacity for incremental adjustment and instead lurches between all-or-nothing extremes
The figure below shows why. The blue segment is the feasible set. The dashed orange iso-cost lines are straight because cost is linear. A straight line sliding across a line segment always hits an endpoint. Flip the cost ranking by a fraction of a cent and the allocation jumps to the other end.
Freeze the price everywhere and that pushback disappears. Every gallon earns identical revenue regardless of destination. The supplier's problem reduces to pure cost minimization. And cost is linear in quantity. A linear objective over a feasible set with corners always lands on a corner. Some markets get filled to capacity. Others get nothing.
The figure below shows why.
The blue segment is the feasible set, all the ways to split a fixed supply between two markets. It has two endpoints. The dashed orange lines are iso-cost lines, and because cost is linear, they're straight. A straight line sliding across a line segment always hits an endpoint. Flip the cost ranking by a fraction of a cent and the allocation jumps to the other end.
Corners are bad enough. But which corner the economy lands on is unpredictable. When delivery costs are nearly equal, a pipeline repair, a refinery outage, a regulatory tweak can flip the entire allocation. Small parameter changes produce discontinuous jumps.
We call this the Chaos Theorem.
How big of a deal is it that we end up at a corner where?
Every textbook draws the Harberger triangle as the cost of a price ceiling. But that triangle assumes reduced supply still goes to the right places. It didn't.
The top row below shows the textbook case: supply spread efficiently, shadow prices equalized, small welfare triangles.
The bottom row shows what actually happens at a corner. One market is fully served. The other bears the entire shortage. Same total supply.
Look at the map again. It's natural to focus on the Northeast. The lines. That's the problem with price controls.
But actually the states with abundant fuel are a sign of the misallocation. Instead of a shortage, they are getting more than they would get without a price control.
How can we estimate welfare in extreme cases?
Standard welfare analysis assumes a demand curve. But price controls destroy the information you'd need to pick the right one. Elasticity estimates work near the previously estimated equilibrium. In the 1974 case, rationed stations received 68 percent of baseline quantity, and many received nothing.
So we developed a bounding approach. No assumed functional form. Across all demand curves consistent with the observed data and plausible demand slopes, what are the largest and smallest possible welfare losses?
No assumed functional form. The key insight: efficient allocation equalizes shadow prices across markets, which collapses what would be an infinite-dimensional problem into a one-dimensional search.
How large was gasoline misallocation in 1974?
This is a theory and methods paper, but we show how to use it in the context of the gasoline shortages. Using station-level AAA survey data presented to President Ford during the crisis, we find exactly the corner-solution structure the chaos theorem predicts: 62.3 percent of stations operating normally, 27.6 percent limiting purchases, and 10.1 percent completely out of fuel.
The shadow price maps tell the story. The Northeast is dark red, consumers valuing gas at multiples of baseline. The Mountain West is blue, below baseline. That gap is the arbitrage opportunity price controls created and simultaneously prevented anyone from exploiting.
To answer that, we need to estimate "shadow price," what consumers would actually pay for one more gallon if they could. When goods are allocated efficiently, shadow prices equalize across markets.
Again, we are bounding this.
How do we do that?
For the upper bound, give the starved markets steep, inelastic demand, so each missing unit costs a lot of welfare. Give the oversupplied markets shallow, elastic demand, so the extra units they got didn't add much. For the lower bound, do the opposite.
The real novel part that makes our multi-market welfare bounds possible is that we then impose that markets add up. That pins everything down to a one-dimensional search.
The shadow price maps show the result. In the upper-bound case, Connecticut's shadow price was 2.5 times baseline. Montana's was 0.7. Shipping a barrel east would have more than tripled your money. That is the arbitrage opportunity price controls created and simultaneously prevented anyone from exploiting.
In terms of WELFARE, we want to look at the misallocation relative to the Harberger triangle.
In our case, the misallocation loss is 1 to 9 times the Harberger triangle. Even at the lower bound, misallocation roughly equals the standard quantity-reduction loss. At the upper bound, the triangle accounts for barely one-tenth of total welfare cost.
As we move into a world where price controls are back in vogue on both sides of the political aisle, let's remember the 1970s. Yes, gasoline lines.
But that wasn't everything.
Chicken farmers gassed, drowned, and suffocated roughly a million baby chicks. “It’s cheaper to drown ‘em than to put ‘em down and raise ‘em,” one Texas farmer explained. Dairy farmers slaughtered cows. Hog farmers culled breeding stock.
In other words, chaos and misallocation.
Paper: briancalbrecht.com/Albrecht_…
A bit deeper write-up on Economic Forces: economicforces.xyz/p/price-c…
Ben Mathew retweeted
As for interest rates, they add up real rates (growth, productivity), expected inflation, expected future rates, risk premium, default premium, liquidity effects. Nobody can pronounce with great authority why they move.
Ben Mathew retweeted
Fascinating piece by Adam Bonica on how the fundraising apparatus preying on elderly donors
data4democracy.substack.com/…
Ben Mathew retweeted
Lots of people are turning to LLMs for financial advice. But what does this advice actually look like?
@TahaChoukhmane, @wdwlin, @AkuzawaMatthew, and I have a new paper that develops and implements a new methodology to describe this advice and why it varies!
Thread ⬇️⬇️⬇️
Ben Mathew retweeted
Dave Ramsey doesn’t understand that stocks are risky.
This quoted post is unavailable.
The logic of the index fund is the following. If each unconstrained investor attempts to hold a mean-variance efficient portfolio, then there’s a good chance that the aggregate portfolio of those unconstrained investors is also mean-variance efficient.
A reasonable approximation to this, within a country, is the free-float weighted market.
Internationally, if some countries don’t allow the domestic investors to invest abroad in foreign stocks, then their free-float weighted market caps are likely overstated for this purpose and should likely be further down weighted.
How do you weight emerging market stocks in your portfolio?
Market-cap weight? Overweight for diversification/valuation? Underweight because of governance, currency, and concentration risks?
Curious where people land and why.
#Investing #Finance #PersonalFinance
53%Market-cap weight
20%Overweight
27%Underweight
15 votes • Final results Ben Mathew retweeted
Ann Carrns from the @nytimes wrote a great article about our latest findings from the Personal Finance Index and yes, the data show we are moving in the wrong direction.
nytimes.com/2026/06/12/your-…
DISPERSION IS HERE
“Now this is not the end. It is not even the beginning of the end. But it is, perhaps, the end of the beginning.”
-- you know who
During the eighth step of the bubble, the flow of new investors starts shrinking while existing investors approach their risk and leverage limits. Volatility and dispersion grow, and gains become less uniform across stocks.
Now, dispersion is here.
Owen Lamont posted this graph today, which illustrates well how cross-sectional dispersion of monthly returns peaks at tops and bottoms.
My interpretation of the graph is not that high dispersion is always a sell signal, or a buy signal for that matter. To me, it's a signal that what has worked very well so far will stop working relatively soon. High beta was great during the late nineties, being short levered small caps was great going into the global financial crisis, and having just cash was great when Covid lockdowns hit. When the dispersion peaked each of those times, what worked on the way in stopped working soon, and what didn't work on the way in started working very well.
The obvious caveat is that we don't know that the dispersion has peaked yet. If this is a bubble, then we are close to the end of the beginning of it, but it's not yet clear whether the correct analogy is April 2000 or December 1999, the two alternative analogies having very different short-term return implications. To build on the analogy of the quote, the battle of El Alamein has started, but it hasn't been won (lost, if you're a Platner supporter) yet.
xitter.cf/ptuomov/status/2054753…
THE LIFE CYCLE OF A BUBBLE
1. A genuine advancement creates real productivity gains. A real technological or economic improvement increases productivity and leads to genuine revenue and earnings growth.
2. Stock prices leak into reported profitability. Rising stock prices improve reported earnings, financing conditions, collateral values, and perceived business performance.
3. Reported profitability drives real investment. Companies increase hiring, capital spending, construction, expansion, and speculative investment because of their own or their customers’ reported profitability.
4. Bubble beliefs and abandonment of present-value discipline. Investors stop focusing on discounted cash flows and begin relying on continuing gains from the greater fool theory, believing they can sell later at a higher price.
5. Inflows from sideline investors. Previously cautious investors enter the market in large numbers. New money from existing and new investors participation drive prices higher.
6. Extreme overvaluation. Prices rise far above historical normal multiples of reported fundamentals, even ignoring the fact that reported fundamentals have been driven by rising stock prices.
7. Issuance. Companies take advantage of high valuations through IPOs, secondary offerings, stock-based acquisitions, SPACs, and insider selling.
8. Exhaustion of inflows. The flow of new investors starts shrinking while existing investors approach their risk and leverage limits. Volatility and dispersion grow and gains become less uniform across stocks.
9. Earnings disappointments from slowing price appreciation. As stock prices stop rising rapidly, the earlier boost from higher valuations into earnings weakens or reverses. Companies begin missing expectations.
10. Stock-price collapse with high volatility. Confidence in both the fundamental growth and in the greater fool theory break down and prices fall sharply. Volatility rises further as leverage unwinds.
11. Bear-market rallies and progressively greater exhaustion. Bargain hunters and frustrated latecomers repeatedly buy the dips, creating violent temporary rallies that fail. Markets make lower highs and lower lows.
12. Capitulation, abandonment, and normalization. Bubble participants eventually give up in disgust or exhaustion. Volatility falls, valuations normalize, and the market returns to more ordinary behavior.
STEP 2 ROCKET FUEL!!!
🚀🚀🚀🚀
The inflated stock prices leak into reported profitability in every large bubble. According to the below link, this is now happening.
(ht Owen Lamont)
My Substack shows how Other Income & Expense from Alphabet/Amazon/Nvidia materially boosted S&P 500's Q1 2026 earnings.
Honored to see Matt Levine discuss it in today's Money Stuff. Thanks, @matt_levine !
Bloomberg: bloomberg.com/opinion/newsle…
My article: baolianwang.substack.com/p/t…
































