Agilent Technologies

(A) - Get Report

warned Thursday that it would earn 18 cents to 22 cents a share, well short of the 35 cents a share forecast by analysts surveyed by

First Call/Thomson Financial

.

The disclosure, made after regular stock market closed, sent Agilent's shares into a tailspin. In after-hours trading, the stock plunged 18 points, or almost 25%, to 55, according to

Instinet

. Agilent's stock had previously closed down 1 1/16 at 73.

The

Hewlett-Packard

(HWP)

spin-off attributed the expected profit shortfall to capacity constraints and component shortages, which have been preventing the company from keeping up with orders. Demand for its testing and measurement equipment and semiconductor products remained strong, the company said.

"We're very frustrated because we're not fully satisfying the unprecedented demand in our communications businesses," Edward W. Barnholt, Agilent's chief executive, said in a statement.

Agilent said weakness in its medical-instrument and chemical-analysis businesses were also contributing to the third-quarter softness. Agilent is scheduled to report its earnings on Aug. 17

Robert Walker, Agilent's chief financial officer, said the company felt comfortable it would meet the fourth-quarter earnings estimate of 39 cents a share.

Agilent's warning comes after a disappointing second quarter, in which the company posted an 11% decline in operating earnings from a year earlier.