A number of tech stocks, buoyed by fresh positive earnings, were on the rise after the closing bell Thursday.

Prominent among these was Advanced Micro Devices ( AMD), which widened its fourth-quarter loss from last year to $1.77 billion, or $3.06 a share. Excluding $2.89 per share in items, however, that handily beats analysts' estimates for a loss of 36 cents a share, per Thomson Financial. Shares of the Sunnyvale, Calif., company were rising 31 cents, or 4.9%, to $6.65, in recent extended trading.

IBM ( IBM) shares were also riding high after the Armonk, N.Y., computer maker thumped fourth-quarter estimates with earnings of $3.95 billion, or $2.80 a share, compared with last year's $2.26 per-share income from continuing operations. Revenue climbed 9.9% to $28.87 billion. Analysts were seeking a profit of $2.60 a share on revenue of $28.24 billion. Shares gained $5.15, or 5.1%, to $106.25.

Xilinx ( XLNX) was adding 5.3% to $20.15 after the California chipmaker pulled in ahead of fiscal third-quarter estimates with income that leapt 34.6% vs. last year to 35 cents a share. And Massachusetts-based Skyworks Solutions ( SWKS), another chipmaker, beat by a penny with rising non-GAAP earnings of 17 cents a share. Its stock was up 4.8% in recent late trading.

Elsewhere, NYSE Euronext ( NYX) took back some of its regular-session losses, recently adding 2.9% to $73.11, after the bourse announced it will take out the American Stock Exchange for $260 million in stock. NYSE also said that Amex members will be entitled to further NYSE shares based on proceeds from the expected sale of Amex's New York headquarters.

On the other hand, Seagate Technology ( STX) gave up 4.2% after predicting current-quarter sales of $3.2 billion to $3.3 billion -- just under the $3.31 billion Street views. For the fiscal second quarter, the disc-drive maker more than tripled its earnings, year over year, to 73 cents a share. On a non-GAAP basis, that comes to 76 cents a share, which claws past the 75-cent average Street projection. Still, shares of the Cayman Islands-based company were losing 90 cents to $20.70.

Elsewhere in the red, sports-apparel maker Under Armour ( UA) took a 17.2% slide after saying it expects to make just 3 cents to 5 cents a share in the first half, having shifted a "substantial portion" of its full-year marketing costs into that period. Analysts are seeking first-half earnings of 39 cents a share, less extraordinary items.

The Baltimore-based company also upped its 2007 sales outlook to around $605 million, up from the prior range of $590 million to $600 million, and pegs earnings at between $1.03 to $1.04 a share. Analysts are looking for revenue of $603.6 million in revenue and a profit of $1.01 a share. Under Armour shares were lately trading at $30.74.

Lastly, Seattle bank Washington Mutual ( WM) saw erratic postclose trading after saying it swung to a fourth-quarter loss of $1.87 billion, or $2.19 a share, primarily thanks to a mortgage-related writedown totaling $1.6 billion. Wall Street had expected a loss of only $1.36 a share. A year earlier, WaMu had pocketed earnings of $1.06 billion, or $1.10 a share. Recently, WaMu stock was flat at $12.46.

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