The companies whose shares are actively trading in Tuesday's morning session include National Semiconductor, Apple, Questcor, Cubist, Intersil, Diamond Foods, Cree and Teekay LNG.
Shares of National Semiconductor (NYSE:NSM) were surged 71 percent after Texas Instruments (NYSE:TXN) agreed to buy the company for $6.5 billion, or $25 per share. Shares were trading up by $10 at $24.07.
Shares of Questcor Pharmaceuticals (NASDAQ:QCOR) jumped $3.10 or 21 percent to $18.02 after its preliminary first quarter revenue topped Street view.
Shares of Cubist Pharmaceuticals (NASDAQ:CBST) soared $4.15, or 16 percent, to $29.40, after it settled a patent dispute with Teva (NASDAQ:TEVA).
Shares of Intersil (NASDAQ: ISIL) soared 10 percent to $13.35 as the TI-National Semi deal boosted chip stocks.
Shares of Diamond Foods (NASDAQ:DMND) advanced 10 percent to $62.90 after it agreed to buy Pringles business from Procter & Gamble Co. (NYSE:PG).
Shares of Apple (NASDAQ:AAPL) fell more than 1 percent after Wall Street Journal reported that Nasdaq plans to slash Apple's weighting in the Nasdaq-100 Index to about 12.3 percent from 20.49 percent.
Shares of Cree Inc. (NASDAQ:CREE) sank 4 percent to $43.90 after it cut its quarterly revenue forecast due to lower sales of LED chips and components.
Shares of Kayne Anderson MLP Investment Co. (NYSE:KYN) declined 5 percent to $30.57 after it priced its public offering of common stock at a discount to yesterday's closing price.
Shares of Teekay LNG Partners (NYSE:TGP) shares were down 5 percent to $38.54 after it priced its public offering of common stock at a discount to yesterday's closing price.