Facebook's purchase of messaging service WhatsApp for up to $19 billion in cash and stock is one of the largest acquisitions ever in the technology sector.
Here are some other notable deals involving US tech companies, in order of dollar amount from largest to smallest:
HEWLETT-PACKARD BUYS COMPAQ - SEPTEMBER 2001
US technology giant Hewlett-Packard buys Compaq Computer for $25 billion in a bid to compete with IBM.
GOOGLE BUYS MOTOROLA MOBILITY - AUGUST 2011
Internet search giant Google buys the handset business of Motorola for $12.5 billion in a bid to challenge Apple in the smartphone market. Less than three years later, Google sold Motorola to China's Lenovo for $2.91 billion.
HEWLETT-PACKARD BUYS AUTONOMY - AUGUST 2011
US technology giant Hewlett-Packard buys British enterprise software company Autonomy for $10.24 billion. US authorities later open an investigation amid HP accusations that Autonomy had engaged in "accounting improprieties."
MICROSOFT BUYS SKYPE - MAY 2011
Microsoft buys Internet voice and video leader Skype for $8.5 billion, the largest acquisition ever by the US software giant.
ORACLE BUYS SUN - APRIL 2009
US business software giant Oracle buys struggling Sun Microsystems and its Java programming language for $7.4 billion.
MICROSOFT BUYS NOKIA - SEPTEMBER 2013
Microsoft buys the handset business of former market leader Nokia for $7.2 billion in an effort to catch up to rivals Apple and Google in the smartphone market.
GOOGLE BUYS YOUTUBE - OCTOBER 2006
Internet search giant Google buys online video platform YouTube in October 2006 from its founders, Steve Chen and Chad Hurley, for $1.65 billion.
EBAY BUYS PAYPAL - JUNE 2002
Online auction house eBay buys online payments firm PayPal for $1.5 billion.
YAHOO BUYS TUMBLR - MAY 2013
Former Google executive Marissa Mayer makes her biggest purchase since taking over as CEO of Yahoo, buying the popular blogging platform Tumblr for $1.1 billion.
FACEBOOK BUYS INSTAGRAM - APRIL 2012
Facebook offers $1 billion for hot smartphone photo-sharing service Instagram. The purchase of Instagram was Facebook's largest until the WhatsApp deal.
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