What happened
Worries about a potential attempt by Russian state bank Sberbank to expand its ownership stake in Yandex (NBIS -2.92%) shaved dozens of percentage points off the Russian internet giant's share price earlier this month. Strong earnings by Yandex earlier this week helped to allay those worries -- as a more profitable Yandex is certainly a good thing for investors, regardless of whoever ultimately controls it.
What's really getting investors excited about Yandex today, though, is this:
According to a UBS analyst -- quoted on TheFly.com -- Yandex "is now considering strategic options with regards to potential hostile takeover defenses." Hearing that, investors rushed to bid up Yandex 9.3% by Wednesday's close.

Image source: Yandex.
So what
If Yandex succeeds in fending off a takeover attempt by Sberbank -- or if, by announcing its determination to do so, it dissuades Sberbank from attempting to buy a blocking stake in the first place -- this would remove a sizable cloud of worry that's been hanging over Yandex stock these past couple of weeks.
Without that worry, investors would be freer to focus on the 39% year-over-year (ruble-denominated) sales growth Yandex exhibited earlier this week -- and the 461% increase in Yandex's per-share earnings.
Now what
Yandex shares currently trade for a mere 14.3 times trailing earnings -- but are pegged for better than 40% long-term earnings growth on Wall Street. At a resulting PEG ratio of just 3.5, I'd argue the only thing standing between Yandex -- and investors recognizing Yandex as an out-and-out bargain of a growth stock -- is the threat of the Russian state coming and taking that bargain away for itself.
Today's 9% price spike on news Yandex doesn't intend to let a takeover happen is the best proof of that.