Even after a bumpy Friday, the S&P 500 index had its best week in two months. Stocks ended Friday mostly unchanged, as traders weighed a weak jobs report for August and tensions between the US and Syria. Traders were rattled by conflicting forces. A mediocre August jobs report suggested that US economic growth was slowing, while providing a reason for the Fed to keep up its stimulus program. The geopolitical risks of Syria added to the uncertainty. One clear trend emerged: Investors moved money into safer assets. The yield on the 10-year Treasury note fell to 2.94 percent from 3 percent the day before.