Yahoo! Inc. (Nasdaq: YHOO) Earnings Preview: Mayer's Perfect Streak Depends on This

This earnings streak doesn't mean the company is in perfect shape. Under Mayer's leadership, Yahoo's core business has actually suffered declining revenue - down 2.2% in 2013. Moreover, Mayer's tenure has failed to boost Yahoo's share in its core business. Its U.S. digital advertisement market share dropped from 6.8% to 5.8% in 2013, according to eMarketer.

Instead, Mayer is credited with a supreme ability to make quality acquisitions. Yahoo! bought more companies in its year and a half with Mayer than the previous 10 years combined.

And that's what YHOO stock investors should key in on today - the health and monetization of the acquisitions Yahoo is now leaning on to boost traffic and advertising.

While these numbers will contribute to whether or not Mayer will be able to maintain her streak, they aren't the deciding factor.

In fact, the performance of this one company alone could make or break Yahoo earnings - and YHOO stock - today...

All eyes are on what Yahoo announces regarding revenue growth and operating margins for Alibaba Group Holding Ltd.

Yahoo's 24% stake in the Chinese e-commerce giant could be responsible for more than 50% of Yahoo! stock value. Alibaba is estimated to be worth over $14 billion, and growing rapidly, according to JP Morgan analyst Doug Anmuth.

On Nov. 11, 2013, Alibaba benefited as $5.7 billion was exchanged on its websites when Chinese shoppers celebrated "Singles' Day." The online consumers spent nearly four times more than U.S. shoppers shelled out on 2012's Cyber Monday ($1.46 billion).

In Q2 2013 - the last earnings period reported - Alibaba generated $1.7 billion in revenue, $856 million in operating income, and $717 million in net income.

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Another big acquisition to watch is Yahoo's stake in Yahoo! Japan. The company is worth an increase of $7 per share to its American counterpart, according to Victor Anthony, managing director for Internet media at Topeka Capital markets, in an interview with The New York Times.

Yahoo! Japan generated $920 million in revenue and $480 million in operating income in Q3.

Finally, look for commentary on user growth and monetization for Internet blogging service Tumblr, which Yahoo acquired in a $1.1 billion acquisition in May 2013.

Acquiring Tumblr was supposed to help Yahoo reach a younger demographic. Additionally, it should help boost Yahoo's ability to implement more targeted ads (by way of providing data points like gender and location information).

Yahoo (YHOO) stock was up 0.9% to $36.99 in afternoon trading before earnings.

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