For many years now, I have been writing about the big four management software makers and how every move they make could impact the overall network and systems management market --redefining how IT executives manage, automate and optimize their environments.

And despite consistently getting poor grades from customers, these incumbent players continue to keep challengers at bay and market their software as critical to IT executives' businesses. One way they do it is by knowing when to build and when to buy technology. Because even on those frequent occasions that I get the chance to write about new and innovative start-ups, more times than not, one of the big four -- BMC, CA, HP and IBM -- eventually acquires the newcomer and works to integrate the best-of-breed technology into their broader suites.

For instance, BMC most recently acquired run-book automation vendor RealOps for an undisclosed amount. And last year HP picked up Mercury Interactive -- a not so small competitor -- in a $4.5 billion deal not too long after Mercury executives detailed to me how Mercury was going to displace the big four and become a market-leading management software maker on its own.

With HP making some 20 software buys since current CEO Mark Hurd came on board in April 2005 and IBM picked up about a dozen software companies in 2006, it doesn't seem likely that any vendors can get ahead of the big four. Yet industry watchers are saying the competition for market share won't come from newcomers, but well-established vendors that will make a significant shift and get into management software.

"The biggest story around the big four … is how they will compete against Microsoft, Oracle, EMC, SAP and Symantec, which are moving more aggressively into the management market. This is already happening," says Will Cappelli, research vice president at Gartner. "Right now the big four still dominate the market, but have lost crucial domains to Microsoft and the Oracle domain is being challenged.

The management market is about $10 billion and growing, Gartner says, and doing so considerably faster than both the middleware and applications market. With the big four owning about 55% of the market, that leaves room for further consolidation among established players, but also opens the door to fringe players looking to expand further into the management market -- companies such as EMC, Microsoft, Oracle, SAP and Symantec. For instance, when Gartner asked IT buyers in a 2006 poll which vendors represent a challenge to the management players, about 35% of 106 people polled said Microsoft and close to 25% pointed to Oracle.

Denise Dubie is senior editor with Network World.