The European Commission has filed antitrust charges against Qualcomm, alleging that the US chip maker tried to stifle competition.
Qualcomm is accused of illegally paying a major customer to exclusively use its chipsets, and selling chips below cost to force rival Icera out of the market.
The commission sent two statements of objections to the company in two separate investigations, which were launched earlier this year.
The regulator gave Qualcomm several months to respond to the charges of exclusivity payments since 2011 and of predatory pricing between 2009 and 2011.
EU Commissioner in charge of competition policy Margrethe Vestager said: "Many consumers enjoy high-speed internet on smartphones and other devices – baseband chipsets are key components that make this happen.
"I am concerned that Qualcomm’s actions may have pushed out competitors or prevented them from competing."
If found guilty of breaching EU antitrust rules, Qualcomm may face a $2.7bn fine, equal to 10% of its 2014 global revenue.
Qualcomm said it has been cooperating with the commission since the outset of the matters.
Qualcomm general counsel and executive vice president Don Rosenberg said: "We look forward to demonstrating that competition in the sale of wireless chips has been and remains strong and dynamic, and that Qualcomm’s sales practices have always complied with European competition law."
Separately, the Taiwan Fair Trade Commission has launched an investigation into whether Qualcomm’s patent licensing arrangements violate the Taiwan Fair Trade Act. The matter is in its early stages.
