After Amazon (AMZN) reported disappointing earnings Thursday afternoon, its stock cratered and is down more than 10% in premarket trading Friday morning. Because Bezos owns close to 84 million shares in the e-commerce giant, that dip means that he is almost $6 billion poorer this morning than he was yesterday.

The stock plunge came after Amazon posted significantly less profit than expected during the holiday quarter, while expenses grew more quickly than investors would have liked. As Fortune’s Barb Darrow pointed out last night, Amazon’s cloud business, Amazon Web Services, continued to grow its top and bottom line at a rate that would make most companies green with envy. But that still didn’t satisfy panicky investors, who were expecting even faster growth in that segment.

Regardless of investor sentiment, Amazon Web Services is obviously a huge profit driver for the company, with earnings from that unit accounting for 142% of the conpany’s profits last quarter.