New Summary: Stocks gain even as shutdown begins

News Summary: Investors keep calm even as a partial shutdown of the US government starts

KEEP CALM AND CARRY ON: Investors stayed calm on the first day of a partial U.S. government shutdown and pushed the stock market to modest gains. At least for now, investors aren't anticipating that the stalemate will cause enough disruption to threaten a gradual U.S. recovery and a four-year bull run in the stock market.

SIGNS OF IMPROVEMENT: A private industry group said U.S. manufacturing expanded at the fastest pace since April 2011 last month on stronger production and hiring. That was encouraging news for investors who were focusing on the economy instead of Washington.

DINNER DATE: Billionaire activist investor Carl Icahn tweeted about his dinner date with Apple CEO Tim Cook. Icahn, who says he owns $2 billion of Apple's stock, tried to persuade Cook to boost the size of the company's stock buyback to $150 billion. Apple rose $11.21, or 2.4 percent, to $487.96.