> The stock immediately fell as much as 10 percent, or $40. Then came word of the potential Prime increase, the first in the program’s nine years.The stock quickly shaved about half its losses, dropping only 4 percent in after-hours trading. Amazon shares were up sharply in regular trading on Thursday. They rose $18.81, to $403.01, just short of the stock’s record high.

A day later and it's back to being down 10%. Wall Street has had some nutty volatility lately: https://www.google.com/finance?q=amzn