John Arnold
9.9K posts

John Arnold
@johnarnold
Co-chair of Arnold Ventures. Reality is more nuanced than the headline.
Houston Katılım Ekim 2013
467 Takip Edilen122.7K Takipçiler

WSJ out today with the anecdote to my point below.

John Arnold@johnarnold
If you can’t convincingly articulate your edge in a market, whether sports betting, prediction markets, stocks, commodities, or whatever else, trading may provide some entertainment but you’ll almost certainly lose money over the long term.
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@JoshLStephenson US consumes about 375 million gallons of gasoline a day, which is up about $1.50. That’s a little more than $500 million a day on US consumers, never mind jet fuel and diesel. US producers make that but it’s an enormous political challenge.
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@johnarnold I would say the the group that is bleeding $500 million a day is probably not winning.
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@natstewart5 @fullbidlift that was very true for a year or 2.
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@johnarnold @fullbidlift Hadn’t a lot of your competition just been wiped out when you started? Meaning you put that edge together at an incredibly advantaged time (to your credit, not easy to do).
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@johnarnold how did you kill it in the NGAS market. You are a legend.
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@fullbidlift Combination of information advantages, modeling capabilities, strong capital backing, and good trading/structuring ability.
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Curious how Jane Street made $40 billion last year with few negative days? Here’s one example:
- Between 1990-2000, there was only one exchange-listed product to trade natural gas: the NYMEX (now CME) physically-settled futures contract
- In 2000, ICE realized there was demand for a financially settled (swap) futures contract and introduced it
- CME countered and listed their own swap future
At this point, the products were primarily for institutional and sophisticated individuals with a commodities account. But as commodities boomed in the 2000s, exchanges created new contracts to increase access and appeal to retail traders.
- the NYSE introduced an ETF (UNG) that followed natural gas prices in 2007
- More ETFs followed that offered ability to bet on a price decline and to get 2x or 3x leverage
- CME introduced a mini contract that was 1/4th the size of the original
The next evolution was to appeal to the pure speculator by expanding the market to less regulated exchanges, widening access globally, increasing leverage, and creating daily bets.
- CME introduced the micro contract that is 1/10th the size of the original
- CME and ICE introduced contracts that expire each trading day
- Hyperliquid and Binance offer unregulated, on-chain, high leverage, perpetual nat gas contracts for non-US uses
- Kalshi offers same day binary contracts. Other prediction markets are moving forward as well.
Now add other iterations on settlement days for the contracts and options on everything listed above.
Note that all of these contracts settle (perps notwithstanding) against the original CME physical futures contract. But instead of one way to trade the product, there are dozens. This creates an opportunity to make markets across all of these surfaces and arbitrage among them. And that's what Jane Street and other similar HFT shops do (among many, many other things).
Nat gas for delivery at Henry Hub, Louisiana is just one product. Take all the ways to trade equities, currencies, commodities, crypto, interest rates, etc across all the different exchanges in all the jurisdictions and the opportunity of making $50 here and $1000 there adds up to an enormous, low-risk money making machine.
This opportunity originates from the large variety of ways people desire to trade random financial instruments and the various products designed for them. This creates a hugely profitable opportunity for the HFTs. They provide a valuable service of creating liquidity for those seeking to trade. Whether that trading is smart and profitable for the average punter on the other side is a different story.
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@johnarnold This happened in Pentagon war games…
x.com/i/grok/share/e…
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@natstewart5 Also "Ending Medical Reversal" by Prasad and Cifu.
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@johnarnold A good book on this problem, if dense and poorly named is "Medical Nihilism" by Jacob Stegenga
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Many years ago I hurt my knee playing sports. I was referred to the orthopedist for one of the local pro teams. After keeping me waiting for 2.5 hours, he diagnosed a cartilage tear and recommended surgery. I was so mad at his manner and tardiness I left without scheduling.
The next week I got a second opinion from a much younger doc who was likely more current on the recent medical literature. He looked at the same MRI. He said he could do surgery now but his advice was to wait 30 days and see if it healed on its own. It did.
Medical reversal is when a practice that became widely used is later shown to be ineffective or even harmful. Examples like meniscus surgery show the need to keep gathering evidence. A not immaterial part of the practice of modern medicine doesn't improve health, and may be net harmful.

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... the American Academy of Orthopaedic Surgeons and the British Association for Surgery of the Knee have continued to endorse the surgery,” he added. “This effectively illustrates how difficult it is to give up inefficient therapies.”
theguardian.com/science/2026/a…
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