DuPont said it earned $417 million, or 46 cents a share, in the three months ended June 30, down from $1.08 billion, or $1.18 a share, a year earlier.
Overall revenue fell 24% to $7 billion from $9.3 billion a year ago and slightly below analysts' forecast of $7.1 billion.
Excluding one-time items, adjusted earnings were 61 cents a share, beating Wall Street's estimate of 53 cents a share.
Drugmaker Merckmrk posted a 12% drop in second-quarter profit, because of lower sales of its cholesterol drugs and several vaccines.
The company said the strong dollar was also a factor, lowering total revenue to $5.9 billion.
The maker of asthma and allergy treatment Singulair and cervical cancer vaccine Gardasil said net income fell to $1.56 billion, or 74 cents a share, from $1.77 billion, or 82 cents a share.
The company said it had restructuring charges and expenses related to its acquisition of Schering-Plough that totaled 9 cents a share. Without that, earnings per share would have been 83 cents.
Analysts polled by Thomson Reuters expected earnings per share of 77 cents and revenue of $5.84 billion.
Results were helped by a 10% decline in marketing and administrative expenses. Moreover, the drugmaker's effective tax rate, excluding special charges and merger-related costs, was 20.4%, a benefit of about 5 percentage points due to favorable tax settlements.
Merck stuck with its full-year 2009 profit forecast of $3.15 to $3.30 a share excluding special items, and its full-year revenue forecast of $23.2 billion to $23.7 billion.
At Schering-Plough sgp, profit jumped 49% in the second quarter, as the company recorded lower one-time costs.
In March, Merck agreed to buy Schering-Plough for $41.1 billion. The combined company would be the second-largest drugmaker in the world by revenue.
The deal is expected to close in the fourth quarter, and the companies said they are cooperating to make the transaction smooth.
Southwest Airlines luv broke a string of three straight losing quarters by scratching out a small profit in the April-June period despite a downturn in travel.
Demand for business travel remains weak, and "we cannot predict a profitable third quarter," said Chairman and CEO Gary Kelly.
Southwest said Tuesday it earned $54 million, or 7 cents a share, in the quarter ended June 30, down sharply from a gain of $321 million, or 44 cents a share, a year earlier.
Excluding one-time items, Southwest said it would have earned $59 million, or 8 cents a share.
Analysts expected profit of 7 cents a share excluding items.
Revenue dipped 8.8%, to $2.62 billion.
United Technologiesutx said its second-quarter profit fell 24% as the diversified manufacturer posted double-digit declines in key businesses.
The diversified manufacturer also cut its revenue guidance for the year and lowered the high end of its profit forecast range.
Net income totaled $976 million, or $1.05 a share, down from $1.28 billion, or $1.32 a share, in same period last year. The latest quarter included 22 cents a share in restructuring costs, and a one-time gain of 6 cents a share.
Revenue slid to $13.2 billion from $15.9 billion.
Analysts expected earnings to be $1.04 a share excluding items on revenue of $13.9 billion.