* Alcoa falls after missing earnings estimates
* U.S. jobless claims fall to 45-year low
* Indexes down: Dow 0.07 pct, S&P 0.04 pct, Nasdaq down 0.08 pct (Updates to open)
Jan 18 (Reuters) - Wall Street's main indexes edged lower on Thursday as declines in healthcare and energy stocks paused a rally that had driven the Dow to its fastest ever 1,000 point gain.
Pfizer fell 0.9 percent and Amgen dropped more than 1 percent, knocking 0.34 percent off the S&P healthcare sector.
The S&P energy index fell 0.16 percent as oil slipped towards $69 a barrel on a reported rise in U.S. fuel stocks.
Alcoa shares sank 8.21 percent after the aluminum producer's quarterly earnings missed analysts' estimates.
Morgan Stanley wrapped up earnings season for the big U.S. banks with a better-than-expected adjusted profit, but its shares slipped 0.43 percent.
"Fourth quarter in terms of net interest margins for money center banks were better than expected, so that's good news. And with interest rates rising, the outlook for financials are pretty good," said Art Hogan, chief market strategist at B. Riley FBR in Boston.
At 9:45 a.m. ET (1445 GMT), the Dow Jones Industrial Average was down 17.44 points, or 0.07 percent, at 26,098.21, the S&P 500 was down 1.18 points, or 0.04 percent, at 2,801.38 and the Nasdaq Composite was down 6.11 points, or 0.08 percent, at 7,292.17.
Economic data in the day was mixed. U.S. homebuilding fell more than expected in December, recording its biggest drop in just over a year, while weekly jobless claims dropped to a 45-year low last week.
Earlier in the day, data from China showed its economic growth accelerated for the first time in seven years, putting world stocks on a firm footing.
"Economic data continues to accelerate both domestically and globally and that is certainly among the key drivers in the market," Hogan said.
Republican leaders in the U.S. Congress intensified efforts to pass a temporary extension in funding government operations and avert a shutdown, scheduling a vote on the measure for later Thursday.
The government is operating on its third temporary funding extension since the 2018 fiscal year began on Oct. 1.
Amazon said it has short-listed 20 cities, including one in Canada, to build its second headquarters after reviewing 238 proposals and expects to make a decision this year. Its shares were down 0.54 percent.
La Quinta Holdings jumped about 5 percent after Wyndham Worldwide said it would acquire the company's hotel operations for $1.95 billion. Wyndham rose 4 percent.
IBM and American Express are expected to report after market close.
Declining issues outnumbered advancers on the NYSE by 1,849 to 787. On the Nasdaq, 1,601 issues fell and 889 advanced. (Reporting by Sruthi Shankar in Bengaluru; Editing by Anil D'Silva)