Google's stock rose nearly 8 percent to $368.93 in after-hours trade on Thursday after Standard & Poor's said the Internet search giant would list on its benchmark S&P 500 Index beginning March 31. The index is comprised of 500 leading companies in the U.S. Some analysts had expected Google to be added last year when its stock price more than doubled in value to top $400. Over the past year, Google has outperformed the S&P. Google has a market cap of more than $100 billion.