* Yellen's speech at Jackson Hole on Friday awaited
* Materials index gains as metal prices rise
* Coty tumbles after reporting a surprise loss
* Indexes up: Dow 0.48 pct, S&P 0.56 pct, Nasdaq 0.78 pct (Updates to open)
Aug 22 (Reuters) - U.S. stocks opened higher on Tuesday, with the Dow gaining more than 100 points, as investors went bargain hunting following a turbulent two weeks, while awaiting the annual central bankers meeting in Jackson Hole later this week.
The S&P has tumbled 2.1 percent in the last two weeks, the biggest such drop since the U.S. presidential election, on concerns over President Donald Trump's ability to legislate his pro-growth agenda.
Still, the index is up about 14 percent since the election.
The central banking conference in Jackson Hole, Wyoming, starts Thursday, with Federal Reserve Chair Janet Yellen's speech on Friday of key interest to market participants.
The speech will be closely watched for a steer on U.S. monetary policy, especially given the persistently low inflation rate, but central bank observers do not expect Yellen to give new guidance.
"The market is in a little bit of a wait-and-see mode as we go into Jackson Hole at the end of the week," said Lindsey Bell, investment strategist at CFRA Research in New York.
"A lot of people are waiting to see what Yellen has to say, especially with regard to inflation and how that might signal the Fed's thinking on the next interest rate hike, if we can still expect something for December."
At 9:40 a.m. ET (1340 GMT), the Dow Jones Industrial Average was up 103.48 points, or 0.48 percent, at 21,807.23 and the S&P 500 was up 13.71 points, or 0.56 percent, at 2,442.08.
The Nasdaq Composite was up 48.16 points, or 0.78 percent, at 6,261.28.
Nine of the 11 major S&P sectors were higher. The top gainer was the materials index, gaining 0.74 percent, helped by a jump in prices of metals, including copper.
Freeport jumped 3.9 percent, also helped by news that Indonesia expects to strike an agreement this month to allow the miner to keep operating its copper mine in Papua.
Freeport was the top percentage gainer on the S&P, followed by Macy's, which jumped more than 4 percent to $20.34 after announcing a restructuring and job cuts.
At the other end was Coty, tumbling about 11 percent following the beauty products maker's surprise quarterly loss.
Medtronic fell about 2 percent to $81.78 after reporting lower-than-expected revenue.
Toll Brothers was off more than 2 percent after the luxury homebuilder posted a revenue miss and tempered its gross margin forecast.
Advancing issues outnumbered decliners on the NYSE by 2,056 to 461. On the Nasdaq, 1,714 issues rose and 560 fell. (Reporting by Sruthi Shankar in Bengaluru; Editing by Savio D'Souza)