What happened

Small-cap tech stock Energous Corporation (WATT -1.82%) had kind of an interesting day today -- and by "interesting," I mean bad.

Demonstrating its WattUp "wireless charging 2.0" technology for charging electronic devices without need for a point of contact (much less a plug) at the Mobile World Congress Barcelona today, Energous also announced a partnership with Chinese smartphone maker vivo Global to "explore integrating WattUp into smartphone designs that charge wirelessly over-the-air."

Energous stock responded by dropping more than 8%, closing the day down 8.2%.

Cartoon characters confused by declining stock chart.

 Image source: Getty Images.

So what

Why might that be? After all, aren't partnerships -- and potential sales of products to a partner -- a good thing for Energous and its WattUp invention?

You'd think so, right? But I can't help but wonder if by tooting its horn in this way, Energous got investors just excited enough about its prospects to take a closer look at its business. Upon doing so, they might have noticed that Energous, valued at $261 million, has no profits (and therefore no P/E), no free cash flow, and hardly even any sales to speak of -- less than $500,000 over the last 12 months.

Check out the latest Energous earnings call transcript.

Now what

Energous has its work cut out for itself, convincing investors that a small-cap tech stock selling for more than 500 times sales is a good investment. Inking a partnership with a top 10 global smartphone supplier is a good first step. A better step would be "beating earnings" and giving great guidance when it reports its Q4 results on Wednesday. That could be difficult, however. Analysts are looking for Energous to report sales of $790,000 for the quarter -- which is more revenue than the company collected in the entire four quarters preceding Q4, combined.

Fingers crossed.