Randstad Holding NV, the world's third-largest staffing firm, began talks to acquire Vedior NV, the fourth-largest, both companies announced today. The Netherlands-based companies would vault ahead of Manpower Inc. (NYSE: MAN) and be second only to Adecco SA if combined.

Randstad said the discussions are in the preliminary stage and there is no guarantee it will ultimately acquire Vedior. However any such deal will include "a significant equity component," according to the company.

Machteld Merens, a spokeswoman for Randstad, said the company can't state a timeline for a possible deal. "We are in friendly conversations with each other," Merens said. "As soon as we know more we will make sure it goes public."

Vedior said it received a proposal from Randstad and the talks between the two companies could lead to a public offer. But it said there's no guarantee of that at this time.

Randstad's 2006 revenue was $10.28 billion and Vedior's was $9.62 billion. A combined revenue of $19.90 billion would send them past Manpower Inc, which had revenue of $17.56 billion in 2006. The largest staffing firm, Adecco, had 2006 revenue of $25.64 billion.

Trading of Vedior shares was halted for a time Friday prior to the company releasing its announcement because of a run-up in the share price. Vedior shares closed at euro17, up 37.96%. Meanwhile the Netherlands Authority for the Financial Markets (AFM) said it began an investigation. "We are starting an investigation to see if there was advanced market knowledge or misuse of knowledge," said Franscé Verdeuzeldonk, a spokeswoman for the AFM. There was no timeline as to when that investigation might end.

Randstad shares fell 0.77% to euro32.37.