
When Apple gaps higher immediately following its after-hours earnings report, the next day it typically gives back some of that gain, declining by an average of nearly 1 percent between the opening and closing bells.
Birinyi Associates studied Apple's post-earnings behavior since 2009. It found Apple stock has gapped up, or shot higher 65 percent of the time right after its earnings report, in the period between the earnings release in the after-hours market session to the last price in pre-market trading.
The average positive gap in that period was 4.7 percent.
Then Birinyi measured the performance from the opening price to the closing price on the next day, and found Apple, whether it gapped higher or lower, has traded lower 65 percent of the time for an average 0.92 percent decline from the open to close.
