Shares of Amazon, the world's largest e-retailer, plunged as much as 11 percent to $172 on Wednesday after the company reported fourth-quarter revenue below expectations. They closed at $179.46, down $14.98 or 7 percent.

The effect was to trim Amazon's market value to only $81.6 billion and slice the value of CEO Jeff Bezos's personal stake by $1.32 billion.

Seattle-based Amazon reported $17.4 billion in revenue for the holiday period, about $900 below estimates, as net income plummeted 57 percent to $177 million, or 38 cents a share, from $416 million, or 91 cents, a year earlier.

Analyst Youssef Squali of Jefferies estimated Amazon sold as many as 7 million Kindle devices during the quarter, including about 4 million Kindle Fire tablets, the $199 devices priced to compete with Apple's iPad 2. Apple earlier reported selling 15.2 million iPads in the calendar quarter. Squali and other analysts had thought far more Kindle Fires had been sold.

The reaction by Amazon shares repeated market reaction Oct. 26, after Amazon reported lower-than-expected third-quarter earnings based on the goals by Bezos to seed the market with new Kindle Fire tablets sold below cost to recoup losses over time selling services.

That day, Amazon shares fell 12 percent in the first hour of trading, erasing $9 billion in value and trimming the personal stake of Bezos by about $2.2 billion.

Since then, Amazon's market value has fallen from $103 billion to $81.6 billion on Wednesday. Amazon CFO Thomas Szkutak Tuesday night said he was confident Amazon's strategy would succeed over time. So far we like [what] we see, he told investors.

The decline in wealth of the Bezos family apparently hasn't changed its plans.

Last month, Bezos, 48, and his wife, Mackenzie, donated $15 million to Princeton University, from which Jeff graduated in 1986 with a degree in computer science and Mackenzie in 1992 with a degree in English. The Bezos funds were designated for a biosciences unit within the new Princeton Neuroscience Institute.