U.S. stocks traded mixed Tuesday, with the Dow Jones Industrial Average dropping 40 points, as investors sifted through a series of quarterly-earnings reports that signaled a strong U.S. dollar is continuing to weigh on corporate results. However, the Nasdaq composite rallied above the psychologically important 5,000 level Tuesday, boosted by gains from biotechnology stocks.

In morning trading Tuesday, the Dow (INDEXDJX:.DJI) dropped 39.93 points, or 0.22 percent, to 17,995.00. The Standard & Poor's 500 (INDEXNASDAQ:.IXIC) rose 3.59 points, or 0.17 percent, to 2,103.70. The Nasdaq composite (INDEXSP:.INX) added 24.34 points, or 0.48 percent, to 5,018.21. 

Shares of Dow component DuPont Co. (NYSE:DD) dropped 3.2 percent Tuesday to $70.52 after the chemical company lowered its earnings outlook for the year, after saying a strengthening U.S. dollar weighed on sales across all of its segments, including a 14 percent and 10 percent decline, respectively, in its agricultural business and chemicals division. DuPont said it now expects currency to bring down its full-year results by 80 cents per share, above the 60 cent negative impact the company first estimated in January.

DuPont reported first-quarter net income of $1.03 billion, or earnings per share of $1.13, on revenue of $9.37 billion, down from a profit of $1.45 billion, or earnings per share of $1.54, as sales rose $10.12 billion a year earlier. Wall Street had expected a profit of $1.31 a share and revenue of $9.41 billion, according to analysts polled by Thomson Reuters.

The chemical company also announced an increase in its quarterly dividend by 4 percent to 59 cents per share.

Meanwhile, the Nasdaq composite rallied over 5,000 on Tuesday, with its biotechnology index gaining 1.5 percent, driven by a more than 8 percent gain from pharmaceutical company Mylan NV (NASDAQ:MYL).

The euro traded lower Tuesday for a second day against the U.S. dollar, falling to $1.07 as concerns grow about Greece’s debt crisis. The European Central Bank is said to be studying measures to reduce emergency funding for Greek banks under its emergency liquidity assistance, Bloomberg reported Tuesday. The U.S. dollar gained 0.4 percent against major world currencies. 

No major U.S. economic data is scheduled for release Tuesday.

Notable companies reporting after the closing bell include Internet giant Yahoo! Inc., restaurant chain Chipotle Mexican Grill Inc., quick-service restaurant company Yum! Brands Inc. and social-game services company Zynga Inc.

Crude oil dipped Tuesday in the midst of growing tensions in the Middle East as investors fear a civil war in Yemen could affect global oil supplies. West Texas Intermediate crude, the benchmark for U.S. oil prices, fell 0.23 percent to $56.25 a barrel, for May 15 delivery, on the New York Mercantile Exchange. Brent crude, the benchmark for global oil prices, fell 0.50 percent to $63.13 a barrel, for June 15 delivery, on the London ICE Futures Exchange.