By Adam Shell, USA TODAY

NEW YORK -- Stocks were trading sharply lower Tuesday after a new batch of weak earnings reports from major U.S.

companies reinforced fears that the economy remains fragile.

The Dow Jones industrial average and the broader Standard & Poor's 500 index were down about 1.4%, while the Nasdaq composite index was off 1.2% in the first half hour of trading.

A trend that started off the quarterly earnings reporting season continues: investor disappointment about weakness in sales and revenues, signaling a lack of demand for goods and services.

TRACK STOCKS: Get real-time quotes with our free Portfolio Tracker Tuesday's earnings misses before the opening bell on Wall Street included two companies in the benchmark 30-stock Dow Jones industrial average.

Chemical maker DuPont's (DD) earnings fell short of analyst expectations by 2 cents; revenue also came below estimates.

Similarly, manufacturing conglomerate 3M (MMM) reported earnings in line with expectations but lowered its full-year guidance, and revenues came in at $7.5 billion, below expectations of $7.6 billion.

UPS (UPS), the package delivery giant that is a good barometer of the economy's health, met analysts' profit estimates but also was shy on revenues.

One exception to the trend: Yahoo late Monday reported results that outpaced analysts' expectations on earnings and revenue. Shares of Yahoo (YHOO) were up nearly 5% Tuesday to just over $16.50 a share.

Still, "a weakening trend in earnings announcements of late has taken some of the optimism out of global markets," Barclays analyst Alan James wrote in a Tuesday report to investors.

Some of the weakness is due to the relative strength of the U.S. dollar, which crimps profits when they are translated into greenbacks from weaker foreign currencies.

What companies say about future quarters also suggests the economy, both at home and abroad, won't re-accelerate anytime soon.

Other signs of those fears are showing up in the price of crude oil and gold, both of which were down sharply Tuesday. Crude oil was trading $87.02, down $1.63, or 1.8%.

Gold futures were down to $1,712.40, down $13.90, about 0.8%.

Heading into Tuesday's earnings reports, 20 of 21 companies in the S&P 500 index that have issued forward guidance have issued warnings that profits or revenue, sometimes both, will be lower than expected in coming months, according to Gregory Harrison, an analyst at Thomson Reuters.

Investors have been loud and clear in their reaction: In its best Jerry Maguire impersonation, Wall Street is saying to Corporate America: Show me the sales! Show me the revenue!

Good news on earnings related to cost-cutting and worker productivity isn't enough, in fact, just isn't cutting it for investors who are grading a company's latest quarterly profit performance.

A sales squeeze is the main story line so far of the quarterly profit reporting season. While six of 10 companies in the S&P 500 have beaten earnings-per-share targets - just below the 62% historical average - revenue misses have been plentiful.

Only 39% of the 123 S&P 500 companies that have reported results have topped analyst revenue estimates, far below the 62% that normally beat, Thomson Reuters data show. Overall, S&P 500 revenue is on track to fall 0.4%, a fifth straight quarterly decline.

"The data reinforce concerns that demand in the economy is weak," says Gregory Harrison, analyst at Thomson Reuters.

The latest revenue shortfalls came Monday from heavy equipment maker Caterpillar (CAT) and toy maker Hasbro (HAS). That follows last week's misses from search engine Google (GOOG) and tech titan IBM.

Stock prices are taking a hit as companies spread the blame. Some are pointing the finger at China, where growth is slowing. Europe, due to its debt woes, is also on the list of excuses.

U.S. consumers get their share of the blame, companies say, since they're buying fewer of everything from toys to burritos.

Even smartphones have been fingered as a revenue shortfall culprit because tech firms are getting fewer ad dollars from smaller digital screens.