* Yellen comments leave rate expectations unchanged on Wall Street
* Core inflation highest since January 2013
* Boeing falls after Bombardier jet report
* Microsoft down after report of Salesforce deal talks
* Indexes end down: Dow 0.29 pct, S&P 0.22 pct, Nasdaq 0.03 pct (Updates to close)
By Noel Randewich
May 22 (Reuters) - U.S. stocks ended weaker on Friday after Federal Reserve Chair Janet Yellen indicated that the central bank was poised to raise interest rates this year, in line with Wall Street's expectations.
Lackadaisical trading volume during the session ended a week of slow activity that has left many investors unconvinced that recent record-high levels are likely to last.
In a speech, Yellen said a rate hike would be warranted this year if the economy keeps improving as expected. She also said it would take several years to return to normal interest rates.
Investors have enjoyed an extended period of low volatility and steady gains, but with the Fed on track to raise rates this year and major indexes near records, the market could get a bit choppier in coming weeks.
"I think what Janet Yellen and all of the Fed officials have been doing is very carefully choreographing their move. I think this is probably the most telegraphed Fed liftoff in some time," said Bruce Zaro, chief technical strategist at Bolton Global Asset Management.
"They're concerned about the markets' reaction."
The Dow Jones industrial average fell 53.72 points, or 0.29 percent, to end at 18,232.02 points.
After trading near flat for most of Friday, the S&P 500 lost 4.76 points, or 0.22 percent, to close the week at 2,126.06. The Nasdaq Composite dropped 1.43 points, or 0.03 percent, to 5,089.36.
Both the Dow and the S&P hit new records this week but Friday's dip left the Dow in the red. For the week, the Dow ended 0.2 percent lower and the S&P rose 0.20 percent.
The Nasdaq added 0.8 percent for the week.
Volume on U.S. stock markets has been below the month-to-date average for several sessions. On Friday, ahead of the Memorial Day long weekend, about 4.9 billion shares changed hands on U.S. exchanges, below the 6.2 billion average this month, according to BATS Global Markets.
All of the 10 major S&P 500 sectors ended lower, led by a 0.8 percent drop in the telecommunication services index .
Shares of Microsoft lost 1.10 percent after CNBC reported the company held significant talks to buy cloud software heavyweight Salesforce.com but failed to agree on a price. Salesforce rose 2.88 percent.
Boeing shares fell 1.72 percent to $144.81 after the Wall Street Journal reported that Bombardier was considering a third model of its CSeries jetliner.
Consumer prices moderated last month, data showed, but the so-called core consumer price index, which strips out food and energy costs, posted its largest gain since January 2013.
The dollar rose to a 3-1/2-week high against the euro and U.S. bond yields rose after the stronger-than-expected rise in core consumer prices.
NYSE declining issues outnumbered advancing ones 1,922 to 1,085, for a 1.77-to-1 ratio; on the Nasdaq, 1,566 issues fell and 1,177 advanced, for a 1.33-to-1 ratio favoring decliners.
The S&P 500 posted 27 new 52-week highs and 3 new lows; the Nasdaq Composite recorded 71 new highs and 36 new lows. (Additional reporting by Lucia Mutikani, Tanya Agrawal and Ryan Vlastelica; Editing by Savio D'Souza and Nick Zieminski)