TEKsystems (Allegis), On Assignment, Randstad Technologies and Experis (ManpowerGroup) rank as the four largest suppliers of information technology staffing in the U.S., according to Staffing Industry Analysts’ 2012 list of largest U.S. IT staffing firms released yesterday.

Allegis’ TEKsystems division ranked as largest overall with market share of 12 percent. On Assignment — fueled by its acquisition of Apex Systems in May 2012 — climbed to the No. 2 ranking with 5 percent market share. Randstad Technologies also had 5 percent market share, followed by ManpowerGroup’s Experis division with 4 percent.

The annual list of largest IT staffing firms includes companies with at least $100 million in U.S. IT staffing revenue in 2012. This year’s list included 32 firms with combined revenue of $13.7 billion and 60 percent market share. For comparison, the 33 firms on the list last year had combined revenue of $13.0 billion and 63 percent market share.

The top five firms this year garnered 29 percent of market share and the top 15 firms controlled 49 percent of market share.

“Firms on the list generated $13.7 billion in U.S. IT staffing revenue, which underscores the enormous breadth of demand for IT professionals among U.S. businesses,” said Research Analyst Timothy Landhuis. “We continue to believe that IT staffing remains a dynamic sector with above-average growth prospects.  Last year, we estimate that significant organic growth was achieved by firms such as Insight Global, The Judge Group, and DISYS, to give just a few examples. We project this segment will grow an additional 8 percent this year.”

Staffing Industry Analysts ranked companies by revenue, according to industry custom, but this ranking should not be taken to imply that a firm with a higher rank provides better service or more value to its shareholders.

Corporate members of Staffing Industry Analysts can access the full list by clicking here.