AIG shares slump; Treasury plans new offering Shares of insurance group American International Group (AIG) fell in heavy trading Monday after the Treasury announced plans to sell shares of the insurance company it acquired as part of the government bailout of the insurer in 2008, at the height of the financial crisis. It would be the third public offering of AIG shares. Buyers purchased $6 billion of AIG common stock in March and $5.8 billion worth in May 2011. AIG has said it intends to buy up to $2 billion of the stock sold in the offering, the Treasury Department said in a statement. AIG bought around $3 billion worth of stock in the March sale, a Treasury official said. In 2008, the Treasury and the Federal Reserve made $182 billion available to prop up the company, which couldn't meet its credit insurance obligations when housing markets crashed. U.S. authorities retain approximately $44 billion of that investment, a Treasury official said. The AIG rescue was the largest U.S. government bailout of a private company in history. AIG shares were down about 5 percent at $31.06 as more than 85 million shares changed hands. The stock has risen from as low as $20 late last year. Among other hot stocks Monday: Shares of Vertex Pharmaceuticals (VRTX) soared 46 percent after the company reported promising results of its new cystic fibrosis drug Kalydeco. The midstage study found the drug, when combined with its experimental treatment for the disease, led to significant improvement in lung function. The data suggested Vertex could have a multibillion-dollar franchise in cystic fibrosis, a life threatening genetic disorder that affects about 70,000 people worldwide. The company's shares were up $16.60 at $54.01. BroadSoft shares (BSFT) slumped after the Internet communications company forecast weaker-than-expected second-quarter results. Shares were off 20 percent at $32.76. The stock has climbed 65 percent since a low of $24.85 Jan. 4. Cognizant Technology Solutions Corp. (CTSH) plunged 16 percent after the information technology services provider lowered its forecast for the full year on low demand, echoing the bleak outlook from other rivals due to the uncertain global economy. Louisiana-Pacific shares (LPX) were up about 5 percent at $9.38 after the building products company posted a net loss that was smaller than the one posted a year ago. Shares in airline giant United Continental (UAL) were up 5 percent at $23.43.