For the first time since June 2009, shares in General Motors (GM) have begun trading on the New York Stock Exchange, opening Thursday at $35. In early morning trading, the Detroit automaker's shares continued to drive higher, up over 8% at one point.

GM's initial public offering is set to become the biggest global IPO ever. The carmaker sold about 478 million shares Wednesday at $33 each, raising $20.1 billion. Including an option that would allow underwriters to sell more shares, GM looks set to raise $23.1 billion.

The IPO values GM at about $63 billion.

The sale of stock will effectively reduce the U.S. government's stake in the company to around 40% from the current 61%, allowing GM to start shedding the embarrassing "Government Motors" nickname and accompanying stigma. The government acquired its stake as part of the bankruptcy process GM agreed to last year. The government poured nearly $50 billion into GM and after the IPO, taxpayers are still owed nearly $10 billion.

The offering was priced well above the earlier anticipated range of $26 to $29. The company has recently reported earnings of $2 billion on sales of $34 billion, as well as a strong balance sheet, with strong cash flow. With its remarkable comeback, GM shares may be on track to continue trading higher, although concerns remain and investors will be hard pressed to forget its problems of the past few years and the many hurdles still ahead.