After its stock pop, Amazon got Whole Foods essentially for free.

For free? Well, if you consider the increase in market capitalization that Amazon is seeing midday, the answer is yes.

Here's the math:

Amazon is paying $13.7 billion in cash for Whole Foods.

Amazon's stock was up $32 and change mid-morning. There are 478 million shares outstanding, so Amazon's market cap has appreciated by about $15.6 billion today.

So, you could argue, they are getting Whole Foods for free, and pocketing $1.9 billion as well.

By the way, here's the joke going around trading desks on Wall Street: "Jeff Bezos said to Alexa, 'Buy me something from Whole Foods,' and Alexa bought Whole Foods."