Patrick McKenzie reads from his 2024 Bits About Money essay on ACATS, the Automated Customer Account Transfer Service that governs how Americans move investment accounts between brokerages, then updates it with regulatory developments (and industry infighting) from early 2026. The essay covers why a system underpinning trillions of dollars in assets was deliberately designed to skip verifying whether transfers are actually authorized, what the three-business-day shot clock means in practice, and how a bad actor armed with a stolen identity and a mobile app can drain someone's retirement account before they notice it's gone. (Good news, though: they’ll almost certainly get it back. Bad news: quite stressful, and it often isn’t obvious when staring at the zero that this is a recoverable condition.)

–
Full transcript available here: https://www.complexsystemspodcast.com/acats/

–
Presenting Sponsors: Mercury & Granola

If you have more interesting hobbies than managing your money, Mercury Personal is built for you. It allows you to automate movement between accounts—allocating paychecks and tax prep the moment they hit—with a sensible permissions model for partners or accountants. It works the way tech people expect banking to work. Go to mercury.com/personal to experience banking built by the same folks Patrick trusts for his business.

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:

Guys what is wrong with ACATS: https://www.bitsaboutmoney.com/archive/how-acats-transfers-work/

–

Timestamps:
(00:00) Intro
(01:49) A brief digression into self-regulatory organizations
(03:04) FINRA regulates asset transfers between brokerages
(04:54) How does one transfer securities account assets?
(06:52) What does an ACATS request actually entail?
(09:44) Brokerages frequently do not verify incoming ACATS requests
(15:28) Recent developments in ACATS fraud
(19:13) Should I be terrified, Patrick?
(20:07) Sponsors: Mercury | Granola
(23:17) Should I be terrified, Patrick? (cont’d)
(24:46) Another fun wonky control
(28:29) A final ACATS story
(29:58) Regulatory updates: FINRA 26-02
(32:34) Comment letters from the industry
(43:20) Outro

How brokerage transfers actually work

Complex Systems with Patrick McKenzie (patio11)

How brokerage transfers actually work