NEW YORK (CNNMoney.com) -- Stocks slipped at the open Wednesday, as investors looked past the morning's mostly upbeat spate of earnings and focused on Amazon.com's disappointing results and bet that the previous session's advance couldn't last.

The tech-fueled Nasdaq composite (down 10.68 to 2,063.22, Charts) lost 0.5 percent.

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The Dow Jones industrial average (down 30.17 to 11,073.54, Charts) fell 0.3 percent in the early going and the broader Standard & Poor's 500 (down 3.38 to 1,265.50, Charts) index lost around 0.4 percent.

Stocks managed an eleventh-hour rally Tuesday at the end of a choppy session, thanks to a slide in oil prices.

But the tone Wednesday was more negative, with investors again worried about slowing economic growth paired with rising interest rates - and the impact such an environment will have on corporate profits.

With no economic reports released Wednesday morning, the focus was earnings news.

Troubled automaker General Motors (up $1.35 to $32.01, Charts) reported a much-better than expected improvement in quarterly operating profit, sending shares up 3 percent at the open.

But GM had less of an impact on sentiment than Amazon.com (down $4.72 to $28.87, Charts), which slumped after it reported quarterly results late Tuesday that fell from a year earlier and missed estimates, on revenue that declined from the prior year and basically met estimates.

In other news, Hewlett-Packard (down $0.73 to $30.60, Charts) said late Tuesday that it would buy Mercury Interactive, a software and business services firm for about $4.5 billion in cash. Hewlett shares dipped 2 percent Wednesday morning.

U.S. light crude oil for September delivery fell 15 cents to $73.60 a barrel in electronic trading ahead of the weekly oil inventories report, due at 10:30 a.m. ET.

Treasury prices fell, lifting the yield on the benchmark 10-year note to 5.07 percent from 5.06 percent late Tuesday. Treasury prices and yields move in opposite directions.

In global trade, major Asian markets were mixed, with the Japanese Nikkei falling 0.8 percent. European markets were mostly higher at midday.

Caution: slowdown ahead.

More on the markets.