The hacking of the Associated Press's Twitter account yesterday has raised concerns over the trustworthiness of information spread through the site, Bloomberg reports. Stocks fell 1 percent Tuesday after a fake tweet about explosions at the White House appeared on the AP's account. The incident puts pressure on the tech company to improve security for users, Wade Williamson, a senior security analyst at Palo Alto Networks Inc., a provider of network-protection tools, told Bloomberg. "The account that got compromised is the big difference here, as opposed to the traditional impersonating-a-celebrity to say something shocking," Williamson said. AP has suspended its Twitter account and the Federal Bureau of Investigation is investigating the matter.