NEW YORK (CNN/Money) - First-quarter earnings per share at General Electric, the No. 1 company by market value, probably fell about 9 percent, as the conglomerate's plastics and power systems business suffered from rising oil prices and the country's march to war.

That's the forecast of Wall Street analysts awaiting General Electric's profit report, due before the market opens Friday.

Fairfield, Conn.-based GE is expected to have earned 32 cents a share in the quarter ended last month on $32.2 billion in revenue, according to First Call, which tracks analysts' forecasts.

GE, which is involved in broadcasting, light bulbs, reinsurance, aircraft engines and medical equipment, earned 35 cents a share on $33.2 billion in revenue in the year-ago quarter.

GE Chief Financial Officer Keith Sherin this month said that the company's medical equipment and financial services units are performing better than expected.

But GE's plastics business has endured rising energy costs. The price of oil, a raw material in making plastics, rose to nearly $40 a barrel this year as the United States neared war with Iraq.

At the same time, the company's power systems unit depends on business from a manufacturing sector that has seen better days. Earlier this month, the Institute for Supply Management said its March index of manufacturing activity fell to 46.2 -- the lowest level since November 2001.

Executives delayed an array of spending decisions during the buildup to war in Iraq, which raised costs for broadcasters like GE's NBC unit.

But investors appear to be betting that the worst may be over for GE (GE: Research, Estimates), whose stock fell 39 percent last year. Company shares are up 24 percent since Feb. 13. At $273 billion, GE is the biggest company by market capitalization.

GE said it will release first-quarter results at about 6:30 a.m. ET Friday and conduct a conference call two hours later.

General Electric shares rose 8 cents to $27.38 Thursday.