(Updates from 3:27 p.m. ET with closing information.)NEW YORK ( TheStreet) -- Chinese Internet leader Baidu ( BIDU) slid 0.96% to $85.60, while online social games maker Zynga ( ZNGA) gained 0.63% to $3.21 after Baidu denied PR*Urgent's press release claiming that the company has offered to buy Zynga for $10 per Zynga share in cash. The false release, which mirrors last November's fake press release from PRWeb saying that Google ( GOOG) made an offer for WiFi company ICOA for $400 million, raised speculation that it was distributed as a mere hoax or to try to manipulate Baidu and Zynga's stock price actions. Microsoft ( MSFT) popped 4.12% to $30.99 after Jeff Ubben revealed that his activist hedge fund, ValueAct Capital, has built up about a $2 billion stake in the software behemoth. Ubben, ValueAct's CEO said at a conference in New York Monday, according to Bloomberg, that ValueAct has amassed around 60 million shares or roughly $1.9 billion in the company -- a good deal, according to Ubben. Ubben thinks that its shares are undervalued give the prospect that Microsoft will overcome declines in PC software demand by building itself into the world's largest cloud computing company in three to five years. Microsoft becomes ValueAct's biggest holding, overshadowing ValueAct's $1.6 billion stake in Motorola Solutions Inc. ( MSI) as of Dec. 31, according to Bloomberg data. Yahoo! ( YHOO) rose 1.56% to $23.83 after the Sunnyvale, Calif.-based company announced a new app for iPhone and iPod Touch, integrating Summly, CEO Marissa Mayer's latest acquisition. DISH Network Corp. ( DISH) rose nearly 2% to $39.73 after Sprint Nextel ( S), the third-largest U.S. wireless carrier said its board formed a special committee to evaluate a $25.5 billion offer from satellite giant and discuss whether it could lead to a superior offer from Japanese wireless operator SoftBank Corp. Google ( GOOG) fell 0.33% to $797.31 after suffering a mini "flash crash" that led to speculation of a "fat finger" trade. The Internet giant is being fined by a German privacy regulator for illegally recording signals from Wifi networks while taking photos for its Street View service. CBS ( CBS) tacked on more than 1.5% to $46.87 after it said it made a minority investment in TV-streaming technology provider Syncbak as the New York-based company tries to make more headway into the mobile audience. Apple ( AAPL) was advancing 1.77% to $397.45 ahead of its scheduled fiscal second-quarter results on Tuesday. Sterne Agee analyst Shaw Wu cut his estimates for the March quarter, but noted that expectations for the June quarter have come down "to reflect an inventory drawdown and pause ahead of 2H refreshes. The good news is that data points appear to be hitting a bottom." Wu still rates Apple "buy" but lowered his price target to $610. BGC Partners analyst ColinGillis upgraded Apple to "buy" from "hold" ahead of the iPhone maker's next product cycle.