* Fed's Plosser says set a fixed amount of bond buys, then end them
* Tesla extends losses; Twitter gets a sell rating
* Indexes: Dow up 0.4 pct; S&P up 0.1 pct; Nasdaq down 0.1 pct
NEW YORK, Nov 18 (Reuters) - Shares of Boeing led the blue chip Dow index above the 16,000 level on Monday while the S&P 500 topped 1,800 for the first time in history.
Boeing Co shares gained 2 percent to $138.77 after the U.S. planemaker, at the Dubai Airshow on Sunday, announced commitments for a total of 259 of its new 777 jets. Worth about $100 billion at list prices, it is the largest combined order in Boeing's history.
While the Nasdaq Composite was less than 20 points away from 4,000, a level it hasn't seen since September 2000, the tech heavy index was down for the day, pressured by social media stocks including Facebook and Zulily.
The round numbers on major levels could provide some technical resistance at first, but clearing them could prompt more buying from investors eager to chase performance.
"The current technical backdrop remains positive with more evidence of a supportive rotation taking hold within the equity market," said Robert Sluymer, analyst at RBC Capital Markets in New York.
"We would need to see evidence that negative momentum and relative performance divergences (in different sectors) are in place to conclude a correction is developing."
Social media stocks were among the day's top decliners with Facebook down 4.4 percent at $46.83, Twitter down 5.4 percent at $41.58 and Yelp down 5.5 percent at $66.87. Twitter got hit by a downgrade by Wunderlich Securities. Zulily Inc shares fell 3.2 percent to $36.50.
Tesla also extended losses, down 8 percent at $124.50, giving up about 22 percent for the month so far.
A number of U.S. Federal Reserve speakers offered more insights into the central bank's stimulus. The latest was Charles Plosser, president of the Philadelphia Fed, who said improved economic and labor market conditions suggest the Fed should set a fixed dollar amount on its current bond-buying program and end the program when that amount is reached.
William Dudley, the president of the Federal Reserve Bank of New York, said on Monday that he was becoming "more hopeful" about the U.S. economy.
But with intervention from the Fed likely to keep interest rates near zero for the foreseeable future, equities are expected to continue to attract yield-seeking investors, even after the Fed begins to scale back its asset purchases.
The Dow Jones industrial average was up 61.84 points, or 0.39 percent, at 16,023.54. The Standard & Poor's 500 Index was up 2.31 points, or 0.13 percent, at 1,800.49. The Nasdaq Composite Index was down 2.78 points, or 0.07 percent, at 3,983.19.
The S&P 500 had earlier hit 1,802.33 and the Dow touched 16,030.28, their highest levels ever. On Friday, both closed at record highs in their sixth straight week of gains.