Yahoo (YHOO) has completed more than 50 acquisitions during the past 16 years. Its $1.1 billion purchase of Tumblr ranks as its fourth most expensive and the priciest in terms of the amount of cash involved.

The only three that cost more, Yahoo's 1999 acquisitions of GeoCities and Broadcast.com and the 2003 purchase of Overture, were entirely or partially financed with Yahoo's stock.

Here's a look at Yahoo's highest-priced acquisitions:

Broadcast.com for stock valued at $8.1 billion in July 1999

GeoCities for stock valued at $6.4 billion in May 1999

Overture for $1.3 billion in cash and stock in October 2003

Tumblr for $1.1 billion, announced in May 2013

Kelkoo for $571 million in April 2004

Right Media for $524 million in cash and stock in July 2007

Yahoo Europe and Yahoo Korea for $501 million in November 2005

HotJobs for $439 million in cash and stock in February 2002

eGroups for stock valued at $416 million in February 2000

Zimbra for $303 million in cash in October 2007

Inktomi for $290 million in March 2003

Interclick for $259 million in December 2011

BlueLithium for $255 million in October 2007

WebCal for stock valued at $201 million in July 1998

Encompass for stock valued at $196 million in May 1999

Maktoob for $164 million in November 2009

Musicmatch for $158 million in October 2004

Kimo.com for stock valued at $157 million in January 2001

Maven for $143 million in February 2008