BigBand Networks Inc. defied jittery markets and a mixed reception by recent technology-sector IPOs by closing up 31% on its first day of trading as a public company.

   BigBand closed at $17 in 4 p.m. Nasdaq Stock Market composite trading, well above its initial-public-offering price of $13 a share.

   The Redwood City, Calif., company's IPO priced above the expected range of $10 to $12 a share, set by underwriters Morgan Stanley and Merrill Lynch & Co. About 10.7 million shares were sold.

   BigBand is the eighth technology stock to go public so far this year, taking the combined value of the deals in the technology sector to more than $1.2 billion, based on data by Dealogic.

   BigBand's debut comes a week after a high-profile IPO, wireless-broadband company Clearwire Corp. disappointed investors, closing below its IPO price on its first day of trading on the Nasdaq. In contrast, security-software company Sourcefire Inc. was more warmly received, closing 4% higher.

   "Given the recent market performance in virtually all sectors, BigBand Networks' opening was particularly impressive," said Scott Sweet, managing director of IPOBoutique.com, an IPO-research service near Tampa, Fla. "With an increased pricing above the original filing range, it is quite apparent that the placement of the stock was particularly well-done in this challenging environment."

   BigBand's network-based platforms enable cable operators and telephone companies to offer subscribers the "triple play" -- video, voice and data services.

   BigBand moved into the black for the first time last year, reporting an $8.9 million profit for the year compared with a $25.5 million loss in 2005. BigBand had an accumulated deficit of $111.3 million at the end of 2006.

   Venture-capital firm Redpoint Ventures holds 22.5% of BigBand compared with 25.8% previously. It didn't sell any shares into the offer.

   Time Warner Inc. has cut its stake in BigBand from 4.1% to 2.9% after selling 360,140 shares.

   BigBand's business has risk, particularly given its concentrated customer base. The market is also competitive with BigBand up against companies such as Cisco Systems Inc. and Motorola Inc.