Fiat SpA may boost its stake in Chrysler Group LLC to more than 51 percent before an initial public offering of the U.S. automaker, Sergio Marchionne, chief executive officer of both companies, told reporters in Turin, Italy today.

Fiat has the right to buy additional shares in the U.S. company beginning today, the CEO said. Fiat may buy shares in Chrysler from a union trust, Marchionne said.

Marchionne said he is considering a merger of the two companies, though he has no timing in mind. A merger is not a priority now, he said.