Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Chinese online video company Tudou Holdings (Nasdaq: TUDO) soared a staggering 145% on Monday after larger rival Youku (NYSE: YOKU) agreed to acquire it for about $1 billion.

So what: The all-stock deal will create China's largest video site, commanding more than one-third of the market. Rising costs and intense competition have made for a particularly tough operating environment lately, so it's no surprise that even Youku shares are up big -- about 14% -- on the news.   

Now what: Upon completion of the deal, the combined company will be called Youku Todou Holdings, owned 71.5% by current Youku holders and 28.5% by current Tudou holders. "We expect to see significant synergies across a number of areas including leveraging licensed content over a larger user base and realizing efficiencies in bandwidth management and other common expenses," said Youku CEO Victor Koo, who will lead the new entity. Of course, as there are still far too many players in the Chinese online video space, the likes of Tencent Holdings,, and Baidu might be solid plays on even more industry consolidation.