Financial regulators are investigating how computer giant IBM awarded share options to its staff earlier this year.
IBM's sales have been hit recently by poor demand in Europe
IBM revealed on Monday that it was the subject of an informal probe by the Securities and Exchange Commission (SEC) and was co-operating fully.
The inquiry is thought to be linked to IBM's announcement of disappointing quarterly trading results in April.
IBM shares dropped by more than 1% in after-hours trading on Monday after news of the investigation emerged.
The inquiry is believed to be tied to how IBM disclosed the cost of employee share options given in the first quarter of the financial year.
At the time, some analysts claimed that IBM indicated that the cost of awarding share options would be higher than it actually turned out to be in order to reduce expectations of its overall trading performance.
IBM's net profit of $1.4bn for the three months to March 31 was well below analysts forecasts, prompting an 8% fall in its shares on April 15.
"The SEC has informed IBM that the informal investigation is not an indication that any violations of law have occurred," the New York based company said in a prepared statement.
The SEC declined to comment publicly on the matter on Monday.