Facebook to buy WhatsApp: A look at 10 biggest tech deals till date

Here are some other notable deals involving US tech companies, in order of dollar amount from largest to smallest

(Also see: Facebook to buy WhatsApp in a $19 billion deal)

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.

(Also see: Lenovo to buy Motorola Mobility from Google 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."

(Also see: HP to pay $10B for Autonomy as it exits mobile)

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.

(Also see: Microsoft buying Skype for $8.5 billion)

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.

(Also see: Microsoft to acquire Nokia's Devices & Services business in 5.44 billion euros deal)

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.

(Also see: Yahoo completes $1.1 billion Tumblr acquisition)

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.

(Also see: Facebook buying photo-share app Instagram for $1 billion)