ARMONK, N.Y. – IBM announced yesterday that the SEC is investigating how the company disclosed its methods for expensing employee stock options in the first quarter. The technology giant described the investigation as informal and said it was cooperating.

When IBM released its first-quarter earnings on April 14, it said employee stock options cut into earnings by 10 cents per share. The consensus analysts’ estimate was 14 cents a share.

The 14-cent figure had emerged in a chart that IBM’s chief financial officer Mark Loughridge put out during an April 5 conference call, when he disclosed what options costs would have been in the year-ago quarter had IBM been expensing stock compensation at the time. He indicated that the then-current quarter’s results would be similar.

Some analysts complained that IBM led them to believe the options-expensing costs would be higher so as to cushion the disappointing results IBM ended up posting. IBM’s first-quarter earnings amounted to 84 cents per share in the quarter, well short of the 90 cents per share analysts had been expecting.

When asked if the company had intentionally misled analysts in order to soften the impact of the relatively weak quarterly earnings, IBM spokesman Ed Barbini would not comment, other than to say that Mr. Loughridge had been clear that stock-option expenses would be lower in 2005 than in 2004.

IBM shares fell 13 cents yesterday to close at $73.88 on the New York Stock Exchange, then fell another 88 cents after the probe was announced.