How is AMZN worth 13 AAPLs?

Updated: May 08, 2012 11:10 AM UTC

Click to enlarge. Source: Jeffrey Forsberg

FORTUNE -- I know that comparisons, as Shakespeare's Dogberry put it, are supposed to be odorous, but this one is beginning to stink.

How can Apple (aapl), with $110 billion in the bank, annual sales of $140 billion and earnings that nearly double every year, be valued so much lower than Amazon (amzn), which has $6 billion in the bank, sales of $50 billion and earnings that fell 35% last quarter?

This is a question that reader Jeff Forsberg has been asking for nearly a year. On Friday he sent the chart above, an updated version of the coiled spring visual metaphor he introduced last June, when Amazon's price-to-earnings ratio was 81 and Apple's was 16.

A year later, it's only grown worse.

As of Friday, Amazon was selling for 184 times earnings and Apple for 13.8, a 13-to-1 gap that grew even wider in Monday's trading.

"This is getting hard to understand," Forsberg writes. "It's almost as if Wall Street is pricing Amazon on the basis of Apple's earnings performance. There's more upside with Apple's median price target than Amazon's, and yet Apple's P/E's is compressed to a level that strains credibility.  By comparison, there's hardly any coil left in Amazon's spring.  What gives?"

What indeed?