NEW YORK (CNN/Money) - U.S. stock markets slipped early Wednesday, as investors took in lower-than-forecast earnings from Alcoa, the first Dow component to report results, and awaited the onslaught of other corporate reports, due in the days ahead.

After 10 minutes of trading, the Dow Jones industrial average (down 51.85 to 10518.96, Charts), the Standard & Poor's 500 (down 4.85 to 1143.31, Charts) index and the Nasdaq composite (down 9.65 to 2050.25, Charts) all traded around 0.3 percent lower.

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The Nasdaq fell sharply Tuesday, retreating after three up sessions partly in response to a profit warning from Nokia, while the Dow industrials managed to eke out another session of small gains.

Optimism about the economic recovery and the first-quarter earnings reporting period fueled the three sessions of gains. While optimism remains, expectations for the results are so high, that any company that falls short or warns it will fall short may see its stock get pummeled, like Nokia Tuesday or Alcoa.

Starting off the first-quarter reporting period after the bell Tuesday, Alcoa (AA: down $0.85 to $35.65, Research, Estimates), the first Dow component to offer its results said it earned 40 cents per share, up from 23 cents a year earlier, due to higher prices for aluminum. However, that was two cents shy of analysts' forecasts and was sufficient to cause the stock to slide.

Among other corporate news in focus Wednesday morning was the late Tuesday announcement that Boeing (BA: down $0.17 to $42.19, Research, Estimates) picked units of General Electric (GE: up $0.05 to $31.57, Research, Estimates) and Rolls Royce to build the engines for its new 7E7 commercial jets, in a deal that analysts say could ultimately be worth $40 billion. The deal was a blow to the engine unit of rival United Technologies (UTX: down $0.45 to $89.30, Research, Estimates).

Treasury prices edged lower, pushing the 10-year note yield up to 4.16 percent from 4.15 percent late Tuesday. The dollar fell versus the euro and was flat against the yen.

Among commodities markets, Brent crude oil futures fell 12 cents to $31.05 a barrel in London. COMEX gold fell $1.10 to $418.70.

In international trading, Asian markets closed mostly higher, although Tokyo's Nikkei fell, while European markets rose at midday there.