Tumblr might be Yahoo’s (NASDAQ:YHOO) 11th acquisition under Marissa Mayer leadership, but it’s the first one to cross the $1 billion mark.

At Yahoo’s third-quarter earnings conference call, Mayer’s first at the company, she announced that she planned on acquiring several small companies that would help Yahoo step up their game in the realm of social apps, smartphones and tablets.

“We're looking for smaller-scale acquisitions that align well overall with our businesses,” said Mayer on the conference call dated Oct 22, 2012. “I think that the size and scale that's comfortable for a great integration, a great product coming out of it is something that's much more in the size and scale of double-digit millions and low hundreds of millions.”

Just two days after that call, Yahoo announced that it had acquired Stamped, most likely for the company’s talent--nine ex-Google employees that are now working for Yahoo’s mobile product team.

Stamped was merely the first of a long string of acquisitions. This May, Yahoo has already acquired five companies, the latest being Tumblr.

Though exact dollar values are unknown, it is likely that all 10 of Mayer’s first spate of acquisitions for Yahoo were under the $100 million mark.

It’s hard to tell how many more companies Mayer will acquire for Yahoo, but one thing's for certain--she’s a pro at this.

“I've done about 20 or so such acquisitions,” Mayer said at that same conference call for Yahoo. And she’s had 11 more acquisitions under her belt since. Check out this timeline of Mayer’s acquisitions, so far:

Marissa Mayer's Shopping Spree
Before Tumblr, Marissa Mayer Acquired These Companies For Yahoo Lisa Mahapatra