NEW YORK ( TheStreet) -- Shares of Nielsen Holdings ( NLSN) and Demand Media ( DMD) are surging in their first day trading on the New York Stock Exchange. Nielsen's shares opened at $24.75, above its initial offering price range of $20 to $22 per share. Shares of the media ratings company are trading up more than 10.5% to $25.43 on volume of 45.4 million. Nielsen's offering is one of at least seven U.S. IPOs scheduled for this week, Bloomberg data shows. Demand Media, an online content company, also debuted on the NYSE today. The company's common stock opened at $23.50, well above its initial offering price of $14 to $16 a share. The stock reached a high of $25 in morning trading and is currently up almost 35% to $22.88. So far over 9.3 million shares have traded hands. --Written by Theresa McCabe in Boston. >To contact the writer of this article, click here: Theresa McCabe. >To follow the writer on Twitter, go to @TheresaMcCabe. >To submit a news tip, send an email to: email@example.com.