There were also discouraging news out of China, giving investors more reason to worry that one of the most important engines of the global economy is sputtering. Auto sales growth slowed in August and imports shrank unexpectedly. Factory output also slid to three-year low last month. The Chinese president warned growth could slow further.Among stocks that made big moves: â¿¿ Sprint Nextel climbed 2.4 percent after the country's third-largest cellphone company was upgraded by an analyst, who said the company's ongoing network revamp would save it money. The stock rose 12 cents to $5.15. â¿¿ LeapFrog Enterprises dropped 80 cents, or almost 9 percent, to $8.35. The educational toy maker's LeapPad product will face new competition from Toys R Us, which announced plans to launch its own tablet computer aimed at children next month. â¿¿ American International Group fell after the U.S. government said Sunday it was selling shares in the insurer that would decrease its holdings below a majority stake for the first time since the bailout of AIG in 2008. AIG's stock lost 69 cents, or 2 percent, to $33.30. â¿¿ Shares of Geron Corp. plunged 56 percent after the company announced two setbacks for its experimental cancer drug. Geron has ended one study and does not expect the drug to succeed in a second. Its stock fell $1.62 to $1.28.