Analyst upgrades:

• Wells Fargo upgraded Prudential (PRU) to outperform from market perform. The firm thinks the company is in a better position than its peers and will be able to more effectively exploit M&A opportunities.
• UBS upgraded Reliance Steel (RS) to buy from neutral based on potential growth through M&A and valuation. The firm raised its target to $50 from $49.
• Deutsche Bank upgraded Eastman Chemical (EMN) to buy from hold on expectations the company's portfolio transformation will drive higher normalized earnings power, which the firm believes is not fully reflected in consensus estimates. Deutsche raised its target price on shares to $70 from $62.
• Amylin Pharma (AMLN) was upgraded to overweight from equal weight at Barclays.
• Cephalon (CEPH) was upgraded to buy from hold at Jefferies.
• Acuity Brands (AYI) was upgraded to outperform from perform at Oppenheimer.

Mobile phones are becoming less and less about calling people. Because of broadband networks, we are seeing multimedia features becoming common fare -- including music downloads, video streaming and even e-commerce.

This requires some complex technology and one of the leaders in the field is Airvana, which is planning to go public.

Airvana develops software and hardware products based on Internet Protocol (IP) technology as well as Qualcomm Inc.'s (NASDAQ: QCOM) CDMA standards. (Qualcomm owns roughly 10.7% of Airvana). Airvana employs about 380 engineers and has plowed $180 million into R&D over the past seven years. With its technology, carriers can deliver broadband-quality services to mobile devices.

The company certainly has serious customer concentration. About 95% of Airvana's sales come through an OEM deal with Nortel Networks (NYSE: NT). But it has been a nice business so far. Last year, Airvana posted $170.3 million in revenues and cash flow of $57.1 million.

The lead underwriters on the IPO include Morgan Stanley (NYSE: MS) and Lehman Brothers (NYSE: LEH). The proposed ticker is AIRV. You can check out the IPO prospectus at the SEC website.

Tom Taulli is the author of various books, including the Complete M&A Handbook and the EDGAR-Online Guide to Decoding Financial Statements.