Stocks ended last week on a high note, after Federal Reserve Chairman Ben Bernanke said the U.S. central bank has more tools, if needed, to stimulate the economy. Also, durable goods orders rose 4.2% in July, more than the 2.5% increases projected, on increased demand for airplanes and automobiles, but bookings softened in other sectors. German Chancellor Angela Merkel and Greek Prime Minister Antonis Samaras held talks, with both reportedly saying that they want Greece to remain in the euro zone and Merkel adding that Germany expects Greece “to stick to its commitments.” Amazon rose 1.88%, touching a new high, as the company unveiled an expanded deal with NBC Universal and as speculation about a new tablet continued. Autodesk plunged 15.6% after the co. missed revenue forecasts for the second quarter of fiscal 2013 and cut its outlook. Morgan Stanley gained 0.4% after a report in The Wall Street Journal that said the lead underwriter of Facebook’s initial public offering has considerable exposure to the social-networking company through equity investments by several of Morgan Stanley’s mutual funds. This week trading could get choppy as investors gear up for Ben Bernanke's closely watched annual speech at the meeting in Jackson Hole. The market will also be sorting through a batch of economic data, including reports on consumer confidence, pending home sales, personal income and spending, as well as Chicago area manufacturing and the Fed's beige book. Implied volatility inched lower on modest trading volumes.