Intel, the world's biggest computer chipmaker, is being investigated by New York Attorney General Andrew Cuomo over whether it broke anti-trust laws.
Mr Cuomo is looking into claims that Intel stopped customers from dealing with rival Advanced Micro Devices.
Intel has cut prices and tried to boost efficiency as AMD has made efforts to become the world's top producer.
Mr Cuomo has issued a subpoena seeking documents and information from Intel over its conduct regarding AMD.
"Our investigation is focused on determining whether Intel has improperly used monopoly power to exclude competitors or stifle competition," Mr Cuomo said.
He added that protecting fair and open competition in the microprocessor market was critical worldwide.
"Businesses and consumers everywhere should have the ability to easily choose the best products at the best price, and only fair competition can guarantee it."
The subpoena seeks documents from Intel regarding its pricing strategy.
Of concern is whether Intel compensated customers for being exclusive and penalised those who were not. The probe is also looking into whether the firm "illegally cut off competitors from distribution channels".
Intel shares closed 0.1% lower at $22.7 by close of trade.