What happened

Roku (NASDAQ:ROKU) stock went off to the races Monday, rising more than 12% before retracing to close the day with a still respectable 4.9% gain.

Why? It seems investors got excited when the company announced  that it has hired Mustafa Ozgen to become its newest senior vice president and general manager in charge of account acquisition, replacing Chas Smith, who is currently in charge of "Roku TVs and players." Smith is expected to leave the company at the end of this quarter.

Roku box and remote

Investors hit the up button repeatedly on Roku stock today -- then had second thoughts. Image source: Roku.

So what

This is good news for Ozgen, surely -- but is it good enough news to justify adding as much as $5.50 per share to Roku's stock price? I mean, on a share count of 77.2 million, that's nearly $425 million in added market cap, which seems a bit much for what seems a rather run-of-the-mill hire.

Granted, Roku played up Ozgen's pluses in the new position. He "has deep business management and consumer electronics industry experience." He previously "served as CEO of both SmartKem Limited and QD Vision which was acquired by Samsung Electronics." He was even a "Commissioned Naval Officer in the Turkish Navy."

Check out the latest Roku earnings call transcript. 

Now what

Could it be that Ozgen, who sold one company to Samsung, is being brought in to help sell Roku as well? And is that what got investors so excited? Well, Roku's doing just fine on its own, having grown its revenue 39% last quarter, and guiding investors to expect 40% accounts growth when it reports Q4 earnings. It doesn't need to sell itself to anybody.

Plus, Ozgen's new title suggests he'll be kept too busy trying to keep new accounts growth growing to have much time left over trying to sell his boss' company to anyone. And maybe it's that realization that explains why Roku couldn't hold onto all of its gains today and ended up rising less than 5%.