Staffing Industry Analysts released its annual list of largest US staffing firms, which includes 143 firms with US staffing revenue that exceeded $100 million in 2017.

“The 143 companies included in this year’s report generated a combined revenue of $83.6 billion and had an estimated 58.6% of market share,” SIA President Barry Asin said. “These organizations stand out for their sizable operations, impressive achievements and as industry leaders in today’s competitive and dynamic ecosystem.”

 The five largest firms in the US are:

1. Allegis Group, $9.53 billion, 6.7% market share
2. Randstad Holding: $4.68 billion, 3.3% market share
3. Adecco: $4.55 billion, 3.2% market share
4. Kelly Services Inc.: $3.62 billion, 2.5% market share
5. Robert Half International Inc.: $3.45 billion, 2.4% market share

Maryland-based Allegis Group topped the list; Kelly Services moved up one spot this year to rank fourth on the list, swapping positions with Robert Half International. Kelly Services’ results include its third-quarter 2017 acquisition of Teachers On Call, the sixth-largest education staffing firm in the US.

“Due in part to the favorable economic environment over the past year, this year’s report highlights the degree to which many large staffing firms continue to grow via both organic initiatives and strategic acquisitions,” said Timothy Landhuis, director of research at SIA. “Consistent with our research findings regarding a robust level of merger and acquisition activity in the US staffing industry, we note that five companies that appeared in last year’s report do not appear in this year’s report because they were acquired by another staffing company.”

The report does have six new firms that did not appear in last year's report.

Among all firms in the report, industrial and IT skill segments were the largest temporary staffing skill segments served this year by revenue, with 45 and 44 companies, respectively.

This year’s report defines “staffing revenue” as revenue generated from the provision of temporary workers to business clients, as well as from “place and search” services (direct hire/ permanent placement and retained search). It also includes revenue from “temp-to-hire” conversions.

SIA corporate members can download the full report online.