IBM last week overtook Microsoft in terms of market value for the first time in 15 years.
IBM's focus on a combination of hardware, software, and services helped it steadily grow its market capitalization and catch up to Microsoft, which has suffered through faster market capitalization gyrations.
IBM's share prices on Thursday closed at $179.17, up $1.62 from Wednesday's close to give Big Blue a market capitalization of $214 billion. Microsoft, meanwhile, saw its Thursday share prices close at $25.45, which was down 12.5 cents for the day, giving it a market capitalization of $213.2 billion.
While Microsoft dropped significantly from its peak through about 2008, and then followed up with a crash to around $150 million right after the economic meltdown, IBM's share prices were relatively steady, falling somewhat from its peaks and taking a fairly steep dive after the recession before steadily rising to its current level.
For IBM, a key strength is its diversified revenue mix, including its strong high-margin services business.
IBM in July said that for its second quarter of fiscal 2011, its global technology services and global business services businesses combined accounted for 56.6 percent of its overall revenue. That compares to 23.2 percent of it revenue coming from software, 17.6 percent from systems, and 1.9 percent from financial services.
And while IBM, which this year celebrated its 100th anniversary, is often thought of as a stodgy old company compared to its peers in the software and Internet markets, the company has managed to continue growing many of its legacy businesses, including its mainframe and Unix server businesses.
Microsoft, on the other hand, depends heavily on the software business. In July, the company reported as part of its fiscal 2011 financial report that software accounted for 83.4 percent of its revenue compared to 3.6 percent from online services and 12.7 percent from entertainment and devices.
IBM's market capitalization towards the close of the stock market on Monday was $208.4 billion compared to $207.6 billion for Microsoft.
The online news site ARS Technica on Monday published a chart showing the market capitalization of several key tech companies, including Microsoft and IBM, over time.
In that chart, Microsoft clearly was the hot tech company leading up to the dot.com boom years, with its market capitalization peaking around $600 billion around early 2000, with IBM reaching twin peaks of about $250 billion shortly before and after the start of the new millennium.