They are generally given some price improvement relative to the public BBO, so the argument is that customers filled via PFOF are better off.

However one second-order effect of PFOF which argues against this is that PFOF makes it less attractive for non-PFOF firms to participate on the exchange. Because small customer trades, which are generally low information content, have been filled off exchange, only the larger and riskier trades trade on the exchange. This causes spreads to be wider on the exchange than otherwise.

Some European exchanges have banned PFOF. I think these exchanges are working OK without it.

The project was to make a wireless joystick for the apple 2. You could go to the basement and fill out an order sheet and get any kind of electronic component. The order was filled on the spot while you stood there.

I didn’t know anything about the assembly written for the project. The mentor did all that. However I got to do all the wire wrapping and some of the other bits. It worked! Good times. No doubt this is one of the reasons I ended up as an engineer…

This seems to be completely absent from the public debate.

Yes, yes I do. Banks do it for their customers today at scale.

Machine based market making tends to work well when markets are operating "normally". When some regime-changing news comes out, it's not uncommon for the over-fit algorithms to perform badly so the managers just turn them off. I.e. liquidity disappears just when it's needed most.

https://www.wsj.com/articles/thinning-liquidity-in-key-futur...

As an analogy in high school physics they give you a problem like someone 2 meters tall shoots a gun and the bullet is moving so many meters per second, how far does the bullet go before it hits the ground. You use your formula for gravitational acceleration and figure it out, and Yeah! you get the right answer.

But you can't use this formula if you really want to calculate how far the bullet goes. You have to take into account air resistance and then you need differential equations and you probably need to approximate an answer with a PDE solver.

That's just the difference between a tool to explore foundational concepts and something that attempts to be actually be useful in the real world...

For forty years (1619-1661), Black Africans came to Virginia as indentured servants rather than slaves. Then Virginia passed a slave law. Slaves were cheaper.

Citation. https://www.pbs.org/opb/historydetectives/feature/indentured...

Comments URL: https://news.ycombinator.com/item?id=1687567

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Another comment that comes to mind is from Warren Buffett, who famously called derivatives "weapons of financial mass destruction" years before the recent blow up.