Among the companies whose shares are expected to see active trade in Tuesday's session are AT&T Inc., Sun Microsystems Inc., Lockheed Martin Corp., DuPont and Amazon.com Inc.

Aflac Inc. (AFL) is expected to report first-quarter earnings of 70 cents a share, according to analysts polled by Thomson First call.

Amazon.com Inc. (AMZN) is seen posting a first-quarter profit of 12 cents a share.

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AT&T Inc.'s (T) first-quarter per-share profit is expected to be 48 cents.

Corning Inc. (GLW) is expected to post earnings of 23 cents a share in its first quarter.

E.I. Du Pont De Nemours & Co. (DD) is seen posting a first-quarter profit of 80 cents a share.

HCA Inc.'s (HCA) first-quarter results are expected to show a profit of 89 cents a share.

JetBlue Airways Corp. (JBLU) is expected to report a first-quarter loss of 20 cents a share.

Lockheed Martin Corp. (LMT) is seen posting earnings of $1.14 a share in its first quarter.

Lucent Technologies Inc.'s (LU) fiscal second-quarter results are expected to shows a per-share profit of 3 cents.

United States Steel Corp. (X) is expected to post earnings of $1.48 a share in its first quarter .

After Monday's closing bell, Sun Microsystems Inc. (SUNW) said its fiscal third-quarter loss widened, despite surging sales. The company also said Chief Executive Scott McNealy has resigned, and will be succeeded by President and Chief Operating Officer Jonathan Schwartz. See After Hours columns.

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CNet Networks Inc. (CNET) posted a first-quarter loss on higher sales, yet the company chopped its full-year profit forecast mostly due to the expensing of employee stock options.

Cognex Corp. (CGNX) said first-quarter profit rose to $8.8 million, or 18 cents a share, from $5.3 million, or 11 cents, a year ago. Sales for the three months ended April 2 advanced to $59 million from $43.2 million in last year's first quarter. Analysts' average estimate stood at 19 cents a share on sales of $61.4 million, according to Thomson First Call.

Con-way Inc. (CNW) said first-quarter net income was $46.4 million, up from $31.1 million last year. Income from continuing operations for the first quarter was $45.5 million, or 83 cents a share, up from $38.9 million, or 69 cents a share, last year. Analysts polled by Thomson First Call were looking for per-share income of 76 cents. The freight transportation company reported quarterly revenue of $1.06 billion, up from $947.7 million last year. Analysts were looking for a result of $1.05 billion.

Chubb Corp. (CB) reported better-than-expected first-quarter earnings as the profitability of the company's professional liability insurance business improved dramatically.

Crane Co. (CR) posted a 50% surge in first-quarter profit on the back of a strong performance in its fluid handling business.

Dov Pharmaceutical Inc. (DOVP) said results from the Phase III trial of its analgesic bicifadine for chronic back pain didn't achieve a statistically significant effect relative to placebo on the primary endpoint of the study.

Everest Re Group (RE) reported first-quarter results that missed analyst estimates after the reinsurer unveiled more losses from the past year's record hurricane season.

Plum Creek Timber Co. (PCL) reported nearly a 10% drop in profit for the first three months of the year on a soft market in the South, though rising sales and strong demand in its Northern timber operations kept its earnings from slipping as far as Wall Street had feared.

Mindspeed Technologies Inc. (MSPD) reported a fiscal second-quarter net loss of $7.11 million, or 7 cents a share, vs. a net loss of $18.4 million, or 18 cents a share, in the year-ago period. Excluding certain items, the per-share loss came in at 4 cents compared with 11 cents last year. Revenue at the Newport Beach, Calif.-based semiconductor solutions company rose to $34.6 million from $26.6 million. Analysts polled by Thomson First Call had forecast a per-share loss of 3 cents on revenue of $35 million.

JDA Software Inc. (JDAS) said its quarterly profit sank 31% and its revenue declined as it failed to close a significant number of deals during the period. The company also said it would acquire supply-chain management software firm Manugistics Group Inc. (MANU) for $211 million in cash.

NutriSystem Inc. (NTRI) said first-quarter net income was $22.3 million, or 60 cents a share, compared with $3.23 million, or 10 cents a share, during the same period last year. Analysts polled by Thomson First Call were looking for per-share income of 41 cents. Revenue for the quarter was $146.8 million, up from $37.4 million last year. Analysts were looking for revenue of $125 million.

Pactiv Corp. (PTV) said it more than doubled its first-quarter profit as it was able to offset some raw material costs and saw lower expenses for product launches.

PartnerRe Ltd. (PRE) said first-quarter net income came in at $193.2 million, or $3.21 a share, up 73% from a year earlier, when the Bermuda-based reinsurer made $111.4 million, or $1.84 a share. Operating earnings, which exclude after-tax realized investment gains and losses, were $133.7 million, or $2.32 a share, versus $67.6 million, or $1.21 a share, a year earlier, the company reported. PartnerRe was expected to make $1.93 a share, according to the average estimate of 14 analysts in a Thomson First Call survey.

Pitney Bowes Inc. (PBI) posted a higher first-quarter profit and offered an upbeat look ahead on rising demand for its digital-mailing products.

Netflix Inc. (NFLX) said it swung to a first-quarter profit on a 47% increase in subscriber revenue.

Rent-A-Center Inc. (RCII) said first-quarter net income was $40.3 million, or 57 cents a share, compared with $42.7 million, or 56 cents a share, during the same period last year. Analysts polled by Thomson First Call were looking for a per-share result of 50 cents. The rent-to-own operator said quarterly revenue was $607 million, up from $601.8 million last year. Analysts were looking for revenue of $600 million.

Ruth's Chris Steak House Inc. (RUTH) said net income rose to $5.9 million, or 25 cents a share, from $2.3 million, or 6 cents a share, in the year-ago period. Total revenue increased 15.5% to $65.4 million. Analysts, on average, expected it to post a profit of 26 cents a share on revenue of $64.8 million, according to Thomson First Call. Comparable restaurant sales rose 6.8% at company-owned restaurants and 5.5% at franchised restaurants. The restaurant operator said it agreed to buy seven franchised restaurants with an option to acquire an eighth unit for $37 million in cash.

W.R. Berkley Corp. (BER) said first-quarter net income came in at $162 million, or 80 cents a share, up 34% from a year earlier, when the property and casualty insurer made $121 million, or 61 cents a share. Operating earnings, which exclude realized investment gains and losses, were $160 million, or 79 cents a share, compared with $121 million, or 61 cents a share, for the same quarter of 2005, the company reported. Net investment income jumped 47% to $131 million and net premiums written increased 8% to $1.3 billion, the insurer added.

YRC Worldwide Inc. (YRCW) reported first-quarter net earnings of $42.1 million, or 71 cents a share, down 16% from $49.9 million, or 96 cents a share, in the year-ago period. On an adjusted basis, earnings came in at 72 cents a share compared with 92 cents a share last year. Revenue rose to $2.37 billion from $1.68 billion. Analysts polled by Thomson First Call had forecast earnings of 68 cents a share on revenue of $2.32 billion.

Slightly higher margins and same-store sales growth in the U.S. helped Yum Brands Inc. (YUM) offset some foreign currency headwinds overseas and post an 11% increase on total revenue growth of 2%.

Zoran Corp. (ZRAN) reported first-quarter earnings of $20.8 million, or 43 cents a share. During the same quarter a year ago, Zoran posted a net loss of $18.8 million, or 43 cents a share. There were 48.5 million shares outstanding in the quarter vs. 43.2 million a year ago. Revenue at the Sunnyvale, Calif.-based developer of circuits for digital video and audio products rose to $142.2 million from $73.9 million.