But "often" does not mean "always." Sometimes the gap wildly understates the reaction.
That truly only tells the story if you left at exactly 4:00 p.m. and didn't return until 9:30 a.m. the next morning.
Chart courtesy of TD Ameritrade
The headline number looked bad, and AMZN instantly dropped $10 -- and on the highest volume of the after-hours session, to boot. The subsequent counter-reaction was quick and painful for anyone that sold the first dip, as the stock ticked at $269 within two minutes. Within seven minutes, AMZN was trading as high as $279. By 4:28 p.m., it was trading around $290. So all told, it had a $40 range low to high, and a $50 round trip if you add in the first $10 drop.
The options expectation I write up is intended to give a general sense of how someone with a delta-neutral, long or short volatility position (say straddles or strangles) would fare on the earnings. So if it goes out at $23, as it did in AMZN, it suggests that option longs and option shorts more or less broke even. But results may certainly vary. A trader with a long volatility curve who traded in the after-hours session certainly had the shot to more than pay for his position. The same trader who sat and waited probably had a bit of a wash the next day.
Conversely, a short volatility trader (say a strangle and/or straddle seller), would have done better sitting on the sidelines and letting the stock settle down. The aggressive short gamma trader might have gotten a serious case of whipsaw.
The takeaway isn't that long gamma traders should stay aggressive, and short gamma traders passive -- just that there's a bevy of moving parts in all these, and the "Options Move" is just a guideline. Look no further than Apple Inc. (NASDAQ:AAPL - 456.83) to see the reverse lesson. Short gamma traders could have sold stock in the $500 or $490 range, down off the close but way higher than the $460 level of one hour later.
Disclaimer: The views represented on this blog are those of the individual author's only, and do not necessarily represent the views of Schaeffer's Investment Research.