Earnings date

Four times a year a public company tells everybody how the last three months went: what it sold, what it earned, and usually what it expects next. The day it does that is its earnings date.

Two things make it unusual. It’s scheduled — announced weeks in advance, so it’s one of the few big price moves you can see coming. And it almost always happens with the market closed, either after the 4 pm close or before the 9:30 am open, which means nobody can trade on the news until the next open. All the reaction gets compressed into that first price.

Say a company closes at $100 on Thursday and reports at 4:15 pm. If the results disappoint, the stock doesn’t drift down through $99 and $98 on Friday morning. It opens at, say, $91, and that $9 happened while you couldn’t do anything about it.

Until a company confirms its date, calendars show an estimate — usually a window of a few days based on when it reported last year. An unconfirmed date can move.