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> Because of this, banks have to publish the interest rate, compound interval, and annual percentage yield separately.

No, the way a subject is trough in school is not the reason banks have to publish all those numbers.

That a look at all the different ways accountant calculate compound interest, and you will see the reason. Anyway, when was the last time banks united to make some rule to make it easier for laypeople to understand what they do?

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Yep. I work in finance. There are a ton of things like this that are just convention. Like treasury bonds being priced in 1/32nd increments. It probably made sense at the beginning, doesn’t now, but the whole market is built around the convention so we’re stuck with it.

Regulation is the other reason. APR is required to be rate-per-period * period-per-year while also accounting for fees. But APY is rate-per-period compounded over a year. These have more to do with the grifts and bubbles that gave birth to the regulations. Again, it made sense at the time and now we’re kind of stuck with it. Not the best standard but better than no standard.

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