The Securities and Exchange Commission is launching an investigation regarding IBM's first quarter earnings and moreover is looking into the company's way for accounting for stcok-based compensation.

In a filing with regulators, IBM said that it "has received a request to voluntarily comply with an informal investigation by the staff of the Securities and Exchange Commission concerning IBM's disclosures relating to IBM's first quarter earnings and expensing of equity compensation."

An informal SEC probe doesn't automatically imply that the agency will necessarily file civil charges.

The company reported first-quarter results that were lower that ones predicted on Wall Street. IBM's net-income figure included a 10-cents-a-share charge for stock-based compensation. This is the first time that the company included the cost of option expensing on its income statement.

Yesterday, IBM's shares were closed at $73.88, down 13 cents.