Even by the bloated standards of high-tech mergers and acquisitions, Microsoft's proposed purchase of Yahoo appears to be the largest ever among technology firms. It is certainly Microsoft's largest. The company mostly buys smaller firms for less than a billion dollars to fill in gaps in its product lineup. But that may be changing. Last year, for instance, Microsoft bought Seattle online advertising firm aQuantive for US$6 billion, its largest ever until the long-rumored Yahoo deal was unveiled on Friday.

Here's how the proposed Microsoft-Yahoo deal compares to some other memorable high-tech acquisitions by the company's main competitors:

Microsoft offers to buy Yahoo

Why: Microsoft wants to buy into the search/online advertising biz. Yahoo is struggling. Their common foe: Google.

Price: US$44.6 billion -- half cash, half stock -- a 62 per cent premium over Yahoo's price a day earlier.

Hostile/friendly: Unsolicited, though the two firms have had discussions during the past 18 months, according to Microsoft CEO Steve Ballmer.

Key premerger stats:

Market cap: Microsoft: US$303 billion; Yahoo: US$25.6 billion

Head count: Microsoft: 78,565; Yahoo: 14,300 (minus 1,000 in layoffs announced earlier this week)

Revenues: Microsoft: US$58 billion; Yahoo: US$7 billion

Net profit: Microsoft: US$16.9 billion; Yahoo: US$660 million

Deal to be completed by: Microsoft is targeting the end of this year, if Yahoo agrees and no regulators call foul.

Other major Microsoft acquisitions:

1999: Visio Corp. (business planning), for US$1.4 billion

2001: Great Plains Software (accounting and CRM), for US$1.45 billion

2002: Navision Software (ERP), for US$1.45 billion

2007: aQuantive (Internet advertising), for US$6 billion

2008: Fast Search & Transfer ASA (enterprise search), for US$1.3 billion