Nov. 5 (Bloomberg) -- PetroChina Co. passed Exxon Mobil Corp. as the world's largest company by market value as it started trading in Shanghai for the first time. PetroChina's Class-A shares more than doubled, advancing as high as 48.62 yuan ($6.52) from their sale price of 16.7 yuan. They reached 45.03 yuan at 9:44 a.m., valuing the company at $1.03 trillion. Exxon is worth $488 billion on the New York Stock Exchange. http://www.bloomberg.com/apps/news?pid=20601087&sid=afq.WPd_zCO4&refer=home That's right $1,030,000,000,000 All these worries about $10B here and $10B there lost on mortgages is nothing. All Merill or Citi should do is sell its shares in China .