Complex Systems with Patrick McKenzie (patio11)

Patrick McKenzie
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We live in a world where our civilization and daily lives depend upon institutions, infrastructure, and technological substrates that are _complicated_ but not _unknowable_. Join Patrick McKenzie (patio11) as he discusses how decisions, technology, culture, and incentives shape our finance, technology, government, and more, with the people who built (and build) those Complex Systems.

  1. 19h ago

    Why banks pay you to use their credit cards

    Patrick McKenzie (patio11) reads his Bits about Money essay on how credit cards make money. The prompt was a listener who wondered how a card can include free travel insurance for someone who never carries a balance. He covers the four ways a card earns revenue (net interest, interchange, fees and marketing contributions), and explains why rewards competition makes some customers in the middle of the credit score ladder persistently unprofitable. He also explains why Europe's interchange cap left cards at about half of electronic payments, while Japan's uncapped interchange quietly pays for the rest of its consumer banking. In a new postscript, he walks through what a proposed 10% APR cap would mean for cardholders at the low end of the market, and how First Republic made sub-10% unsecured loans work by treating them as a way to win deposits. –Full transcript available here: https://www.complexsystemspodcast.com/why-banks-pay-you-to-use-their-credit-cards/  –Presenting Sponsors: Mercury & Granola Complex Systems is presented by Mercury—radically better banking for founders. Mercury Spend hands your team and agents their own cards with limits you set once, so nobody waits on you to approve a SaaS invoice and nobody chases a receipt. Apply online in minutes at https://mercury.com/.  If meetings consistently leave you with hazy action items and lost context, Granola handles the transcription so you can actually participate and gives you searchable notes afterward. Try it free at granola.ai/complexsystems with code COMPLEXSYSTEMS – Links: How credit cards make money: https://www.bitsaboutmoney.com/archive/how-credit-cards-make-money/ – Timestamps: (00:00) Intro(01:11) How credit cards make money(01:55) Bundling and unbundling(03:12) Revenue levers for credit cards(03:23) Net interest(06:19) Interchange(07:34) Interchange makes cards so valuable you're paid to use them(10:02) Fees(10:50) Marketing contributions(13:05) Debit cards: a horse of a different color(13:32) Sponsors: Mercury | Granola(16:54) Postscript(25:27) Wrap

    Why banks pay you to use their credit cards

  2. 6d ago

    Stranded? Who pays when air travel breaks

    Patrick McKenzie (patio11) got stranded overnight after a backhoe severed a single fiber optic cable, knocking out air traffic control across much of the eastern US. His airline declined to pay for the hotel. In this episode, he walks through who actually owes you what when air travel breaks: federal refund rules, the airlines' "controllable delay" commitments, credit card trip delay coverage, and the goodwill credit a well-placed phone call can unlock. Along the way, he explains why checkout-page travel insurance pays back only about 40 cents on the dollar and why 5,000 apology miles are worth about $60. –Full transcript available here: https://www.complexsystemspodcast.com/stranded-who-pays-when-air-travel-breaks/  –Presenting Sponsors: Mercury & GranolaComplex Systems is presented by Mercury—radically better banking for founders. Mercury Spend hands your team and agents their own cards with limits you set once, so nobody waits on you to approve a SaaS invoice and nobody chases a receipt. Apply online in minutes at https://mercury.com/ If meetings consistently leave you with hazy action items and lost context, Granola handles the transcription so you can actually participate and gives you searchable notes afterward. Try it free at granola.ai/complexsystems with code COMPLEXSYSTEMS –Links:Seeing like a Bank: https://www.bitsaboutmoney.com/archive/seeing-like-a-bank/  –Timestamps:(00:00) Intro(00:38) A severed fiber cable and a double misconnect(02:25) The dangerous professional approach to travel disruption(05:09) Delay codes and why the cause matters(06:57) Tiered customer service at airlines(08:29) Who to talk to at the airport(12:03) Remote customer support and the trouble with chat(17:02) Waterfall item one: the DOT automatic refund rule(19:38) Sponsors: Mercury | Granola(22:57) Waterfall item two: airline commitments and controllable causes(26:18) Waterfall item three: why paid travel insurance is a bad product(30:05) Credit card travel benefits(32:37) Waterfall item four: asking the airline for a goodwill credit(36:17) Politeness, magic words, and negotiating the credit(39:24) Last resorts: DOT complaints and small claims court(41:02) Wrap

    Stranded? Who pays when air travel breaks

  3. Sep 17

    Forced vacations are a fraud control

    Patrick McKenzie (patio11) reads his Bits About Money essay "Financial systems take a holiday" (originally published February 2024), prompted by a conversation with a prior guest about how even exchanging calendars between financial institutions is hard. He explains why banks run at something closer to "five twos" of uptime than Google's five nines, using Japanese banks' idiosyncratic, company-specific "Company Foundation Day" to show how a holiday can be entirely real and consequential while appearing on no official list anywhere. –Full transcript available here: https://www.complexsystemspodcast.com/forced-vacations-are-a-fraud-control/    –Presenting Sponsors: Mercury & Granola Complex Systems is presented by Mercury—radically better banking for founders. Mercury Spend hands your team and agents their own cards with limits you set once, so nobody waits on you to approve a SaaS invoice and nobody chases a receipt. Apply online in minutes at https://mercury.com/.  If meetings consistently leave you with hazy action items and lost context, Granola handles the transcription so you can actually participate and gives you searchable notes afterward. Try it free at granola.ai/complexsystems with code COMPLEXSYSTEMS – Links: Source essay: https://www.bitsaboutmoney.com/archive/financial-systems-take-a-holiday/Alex Elliott on Complex Systems: https://www.complexsystemspodcast.com/episodes/two-banks-cant-agree-on-fourth-grade-math/ – Timestamps: (00:00) Intro(01:31) Financial systems take a holiday(03:29) What is a holiday, anyway?(10:33) Fun operational consequences of holidays(15:07) Sponsor: Mercury | Granola(18:27) Fun operational consequences of holidays (cont’d)(21:29) "This is crazy. Let's get rid of holidays"(26:31) Will this change?(27:55) Wrap

    Forced vacations are a fraud control

  4. Sep 3

    Everyone wants to be your wallet

    Patrick McKenzie (patio11) reads his Bits About Money essay on the business of wallets, with new commentary, prompted by paying his barber $100 over Venmo and wondering why PayPal so badly wants to be in the middle of that transaction. He walks through the economics that make wallets irresistible to anyone already moving money for users: funds enter the ecosystem at card interchange rates, move inside it at the cost of a database transaction, and get topped up over ACH pulls that cost about five cents at scale. From there he covers co-branded debit and credit cards, the loss-sharing language in PayPal's 10-K, Apple's 15 basis points on Apple Pay, and why a checkout page crowded with payment buttons starts to look like advertising inventory. –Full transcript available here: https://www.complexsystemspodcast.com/everyone-wants-to-be-your-wallet/ –Presenting Sponsors: Mercury & Granola Complex Systems is presented by Mercury—radically better banking for founders. Mercury Spend hands your team and agents their own cards with limits you set once, so nobody waits on you to approve a SaaS invoice and nobody chases a receipt. Apply online in minutes at https://mercury.com/.  If meetings consistently leave you with hazy action items and lost context, Granola handles the transcription so you can actually participate and gives you searchable notes afterward. Try it free at granola.ai/complexsystems with code COMPLEXSYSTEMS – Links: Source essay: https://www.bitsaboutmoney.com/archive/the-business-of-wallets/Link: https://stripe.com/payments/link – Timestamps:(00:00) Intro(03:06) The big question about wallets(04:11) Wallets show up early in the life of the Internet(06:01) Stocks, flows, and whatever the heck a wallet is(09:21) What does an ACH pull cost?(11:01) Extensions on the basic wallet model(11:38) What's in your wallet? A new debit card(14:49) Sponsors: Mercury | Granola(18:09) What's in your wallet? A new debit card (cont’d)(23:06) Put the wallet on the phone already(24:50) That smells like an ads business(27:33) Speaking of Stripe and wallets(32:52) Wrap

    Everyone wants to be your wallet

  5. Aug 27

    How AI detection actually works, with Pangram’s Max Spero

    Patrick McKenzie (patio11) is joined by Max Spero, co-founder and CEO of Pangram Labs, which builds models that identify AI-generated text and images. Max goes under the hood to explain how AI detection actually works. They also discuss the institutions that quietly assumed writing was expensive: credit bureaus that negotiated the right to shred templated dispute letters, grant committees where reading the application is five percent of the work, and unemployment offices staffed for a world where claims cannot plausibly rise two hundredfold.  –Full transcript available here: https://www.complexsystemspodcast.com/how-ai-detection-actually-works-with-pangrams-max-spero/ –Presenting Sponsors: Mercury & GranolaComplex Systems is presented by Mercury—radically better banking for founders. Mercury Spend hands your team and agents their own cards with limits you set once, so nobody waits on you to approve a SaaS invoice and nobody chases a receipt. Apply online in minutes at https://mercury.com/. If meetings consistently leave you with hazy action items and lost context, Granola handles the transcription so you can actually participate and gives you searchable notes afterward. Try it free at granola.ai/complexsystems with code COMPLEXSYSTEMS – Links: Pangram Labs: https://textguard.ai/ – Timestamps: (00:00) Intro(00:27) Why AI detection exists(01:42) Friction as a rate limiter(05:42) What Pangram actually does(06:57) Authorship identification at scale(11:01) Common Crawl and the crawling arms race(15:52) Being in the weights(18:08) Ghostwriting letters to banks(19:45) Templated letters and the FCRA loophole(22:38) The anti-memetic property of LLM text(25:28) Value above the weights(27:03) What happens to programmers(30:19) Sponsors: Mercury | Granola(33:39) Jevons Paradox and the compiler(36:44) What comes after the coding harness(40:19) Mode collapse and the dinner recommendation problem(43:00) The patio11 fan blog(45:58) Cognitive surplus and the dead internet(49:40) Is this fight winnable?(54:35) Reputation and disclosure norms(58:02) Training on books and moral standing(01:01:52) Attention, phones, and what we've gained(01:04:17) Wrap

    How AI detection actually works, with Pangram’s Max Spero

  6. Aug 20

    Two banks can't agree on fourth-grade math | Alex Elliott

    Patrick McKenzie (@patio11) is joined by Alex Elliott (@alexpotato), who has spent his career in SRE and operations roles at financial firms ranging from ten-person fintechs to global investment banks, to discuss what the back office actually does all day. They cover the life cycle of a trade: execution, clearing, settlement, and the constant reconciliation between counterparties who don't quite agree on what happened. Alex recounts the Friday afternoon when twenty million shares went out to the street instead of five, and Patrick explains what happens between 4:15 and 4:30 when one bank owes another $36 million and the person who owns that process is on vacation. –Full transcript available here: https://www.complexsystemspodcast.com/two-banks-cant-agree-on-fourth-grade-math/ –Presenting Sponsors: Mercury, MongoDB & Granola Complex Systems is presented by Mercury—radically better banking for founders. Mercury's new feature Command brings an LLM directly into your banking interface, so checking balances, finding invoices, or sending a wire is as easy as asking. Apply online in minutes at https://mercury.com/.  If meetings consistently leave you with hazy action items and lost context, Granola handles the transcription so you can actually participate and gives you searchable notes afterward. Try it free at granola.ai/complexsystems with code COMPLEXSYSTEMS What's the point of building faster with AI if your database can't keep up? MongoDB's native data model mirrors the language LLMs already speak. Ship at the speed of AI while staying ACID compliant at Fortune 500 scale. Start building at https://mongodb.com/ai. – Links: Alex’s website: https://alexpotato.com/ – Timestamps: (00:00) Intro(01:48) The life cycle of a trade(04:37) Why you don't know who you traded with(06:01) Hiding a large block trade(10:04) Information walls inside financial firms(12:49) What the middle office does: managing positions(15:41) Calendars, time zones, and other sources of gibbering madness(19:37) War story: twenty million shares out the door(22:45) Sponsors: Mercury | Granola(25:50) Ops as an iterated game(28:53) Busting trades and who has the authority(33:38) Sponsor: MongoDB(34:29) Inside the Knight Capital collapse(35:49) Agreements, obligations, and who you have to call(36:57) Reconciliation, FTP files, and the humans behind them(39:16) Deadlines, cutoffs, and the $36 million phone call(44:26) How two banks fail to agree on fourth-grade math(48:54) When the golden record goes down(51:55) Finding the one person who can sell the position(54:09) How much business do we do with Fidelity?(56:38) Prime brokerage and extending credit(01:01:03) Smart flow, dumb flow, and payment for order flow(01:02:45) Wrap

    Two banks can't agree on fourth-grade math | Alex Elliott

  7. Aug 13

    LLMs and the economics of Evil, Inc., with Manish Goregaokar

    Patrick McKenzie (patio11) is joined by Manish Goregaokar, a senior software engineer and member of the Rust security response team, to discuss what LLMs do to the cost side of running a sophisticated con. They walk through a scam built for programmers: a plausible company, a few rounds of interviews, and an NDA signed via "sign in with email" that quietly hands an attacker the identity account everything else resets against. A version of it hit at least five people in the Rust community within days of Manish publishing on the subject, and Patrick describes being targeted himself by someone posing as a Bloomberg reporter who wanted him on a Zoom call with a codec problem. They also cover money mules and the three stages of laundering, the $25 million Hong Kong transfer authorized on a fully deepfaked video call, and why the only durable individual defense is refusing to trust any communication you did not initiate. –Full transcript available here: https://www.complexsystemspodcast.com/what-llms-do-to-the-economics-of-scams-with-manish-goregaokar/ –Presenting Sponsors: Mercury, MongoDB & Granola Complex Systems is presented by Mercury—radically better banking for founders. Mercury's new feature Command brings an LLM directly into your banking interface, so checking balances, finding invoices, or sending a wire is as easy as asking. Apply online in minutes at https://mercury.com/.  If meetings consistently leave you with hazy action items and lost context, Granola handles the transcription so you can actually participate and gives you searchable notes afterward. Try it free at granola.ai/complexsystems with code COMPLEXSYSTEMS What's the point of building faster with AI if your database can't keep up? MongoDB's native data model mirrors the language LLMs already speak. Ship at the speed of AI while staying ACID compliant at Fortune 500 scale. Start building at https://mongodb.com/ai. – Links: Manish Goregaokar’s blog: https://manishearth.github.io/  Manish on X: https://x.com/ManishEarth– Timestamps: (00:00) Intro(00:27) The future of the con is already here(01:40) Scams are run like businesses(03:30) A scam aimed at programmers(05:12) Why single sign-on is the one ring to rule them all(06:50) Persistent threats against individuals(08:58) What LLMs change about cost(11:40) Manual scams and business email compromise(14:30) How money movement constrains scammers(17:39) The industry that helps you pay ransoms(19:32) Bespoke attacks on individual targets(21:41) The Rust community gets targeted(23:02) Supply chain attacks and long-lived impersonation(24:58) Money mules and the three stages of laundering(28:35) Why law enforcement struggles with internet crime(30:01) Sponsors: Mercury │ Granola(33:03) Patriotic hackers and the post-Soviet talent pool(35:27) What individuals can do(36:27) Only trust communication you initiate(38:21) Wire fraud in real estate closings(41:07) Why legitimate institutions look like scams(45:22) Who eats the loss(47:21) Sponsor: MongoDB(48:12) Why banks can't just block new payees(50:45) Verification protocols and family passwords(53:07) Urgency and secrecy(54:44) Systemic fixes and who pays(57:55) Open weights and the coming wave(01:02:17) Wrap

    LLMs and the economics of Evil, Inc., with Manish Goregaokar

  8. Aug 6

    The economics of putting germicidal light in every room, with Misha Gurevich and Vivian Belenky of Aerolamp

    In this episode, Patrick McKenzie (patio11) is joined by Misha Gurevich, CEO of Aerolamp, and Vivian Belenky, its chief scientist and a researcher at Columbia, to discuss why UVC, a wavelength of light that inactivates airborne pathogens but is absorbed harmlessly by the dead outer layer of human skin, remains almost entirely undeployed. They explain the physics and safety case for 222 nanometers, the economics of installation, and preliminary South African trial results showing 90% suppression of tuberculosis transmission in hospital wards.  –Full transcript available here: https://www.complexsystemspodcast.com/the-economics-of-putting-germicidal-light-in-every-room/ –Presenting Sponsors: Mercury & MongoDB Complex Systems is presented by Mercury—radically better banking for founders. Mercury's new feature Command brings an LLM directly into your banking interface, so checking balances, finding invoices, or sending a wire is as easy as asking. Apply online in minutes at https://mercury.com/.  What's the point of building faster with AI if your database can't keep up? MongoDB's native data model mirrors the language LLMs already speak. Ship at the speed of AI while staying ACID compliant at Fortune 500 scale. Start building at https://mongodb.com/ai. – Links: Aerolamp: https://aerolamp.net/ – Timestamps: (00:00) Intro(00:58) What far UVC does to pathogens(03:25) Why it's safe for skin and eyes(09:24) What a typical deployment looks like(11:21) Why isn't this everywhere already?(13:55) Where the rollout should be prioritized(17:31) The economics per room and per building(20:56) Lamp lifetime and maintenance(21:48) When does the evidence become undeniable?(23:24) Tuberculosis and long-term care as early proof points(27:16) Pandemic math and kneecapping the next outbreak(30:16) Sponsors: Mercury | MongoDB(32:49) R0, K-factor, and why the built environment beats opt-in(34:23) Building codes, ASHRAE 241, and competing technologies(39:11) The deployment curve and the awareness problem(42:33) Scaling manufacturing: krypton chloride versus LEDs(45:14) Price versus cost, and where the inflection point is(47:35) Should you put one in your house?(51:51) What would make this fail?(56:09) The hygiene hypothesis objection(01:01:13) The precautionary principle and reasoning under uncertainty(01:06:04) Where the first million dollars should go(01:10:49) The business case and the heckler's veto(01:14:51) Where to find Aerolamp(01:15:52) Wrap

    The economics of putting germicidal light in every room, with Misha Gurevich and Vivian Belenky of Aerolamp
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We live in a world where our civilization and daily lives depend upon institutions, infrastructure, and technological substrates that are _complicated_ but not _unknowable_. Join Patrick McKenzie (patio11) as he discusses how decisions, technology, culture, and incentives shape our finance, technology, government, and more, with the people who built (and build) those Complex Systems.

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