Updated from 4:51 p.m. EDT

Shares of

RSA Security

(RSAS)

dropped sharply after the closing bell Monday, when the company announced it would miss its first-quarter sales and earnings targets by a wide margin.

After a brief trading halt, shares plunged rapidly in recent after-hours trading, losing about one-quarter of their value in just a few minutes. The stock recovered a bit and was off $3.08 a share, or 19.4%, to $12.79. RSA ended the regular session at $15.87 a share.

RSA, which sells enterprise security solutions, said revenue in the March quarter will range from $74 million to $76 million, slightly more than the $72 million in sales posted a year ago but well below the guidance of $81 million to $84 million the company issued in January.

Net income will range from 8 cents to 10 cents a diluted share, compared with earlier guidance of 13 cents to 15 cents a diluted share. A year ago, the Bedford, Mass.-based company posted a profit of 10 cents.

The first quarter of the year is normally slow for RSA, but sales to technology customers dipped below normal in March, the company said.

The company's authentication business was solid, but software sales overall were far below expectations. Company executives, who seemed unsure of what caused the shortfall, said it hit across all major geographical units.

"This was not indicative of anything that will turn around in one quarter," CEO Arthur W. Coviello said in a conference call with analysts after the announcement. He added that this might be the beginning of an industrywide slowdown.

RSA will issue final results for the quarter on April 27.