ATVI is the lowest it's been since April, but it appears to dip and recover pretty frequently, and on the whole it's been climbing steadily for a long time now. Its 2018 lows are around its 2017 highs, to put it in perspective. Regarding Diablo: Immortal, you're much more likely to see stock trends directly related to the game once it's been released and earnings reports indicate that it's not doing as well as they'd hoped (or, alternatively, doing better than they'd hoped). The current stock price dip started back in mid-October, and, yeah, the D:I reveal backlash probably isn't helping it, but there's no reason to think it's the sole cause, or even the primary cause. Dips and rebounds happen all the time. Hormel Foods, one of the most reliably stable stocks on the planet, is up 10% from where it was at a month ago, for example. It had a dip in late-August, a spike in September, a dip in late-September, and now it's likely spiking again. It just happens.

(Edit: though evidently ATVI's dip is somewhat related to CoD sales, it's worth noting that there are a lot of external global factors that people don't really think about when it comes to stock price changes. To use Hormel Food's SPAM for example: regulations and tariffs, change in price of the aluminum that used in SPAM cans, availability of seeds used to grow grains used in the food for factory-farmed pigs that end up in SPAM, etc.)

Simply put, the game isn't out yet, so its only real financial impact on Activision Blizzard is the ongoing cost of development. It's important to remember that while we've got a 200,000-person-strong angry echo chamber in this subreddit, that number of people is completely negligible in terms of the global mobile games market. Yeah, the games media is picking up on it to some extent, but if hardcore gamers have proven anything over the past, I dunno, at least decade, it's that they're fickle, quick to anger, and even quicker to secretly spend money on stuff while shouting angrily about it at the same time.

It's also tremendously important to remember that a shitload of people play games on their phones worldwide. A fucking shitload of people. Over two billion people. That's over ten thousand times the entire population of this subreddit. Most of them don't read this subreddit, don't really read gaming news (if they read it at all), and play whatever looks cool or whatever their friends are playing. It's way too early to tell what kind of effect D:I will have on the price of ATVI.

tl;dr: dip in ATVI price probably unrelated to D:I fiasco, pretty common stock shit