By Alexandra Scaggs 

U.S. stocks inched lower in morning trading, pausing after the S&P 500 index closed above 2000 for the first time.

The Dow Jones Industrial Average was little changed, slipping less than 0.1% to 17103. The S&P 500 index declined one point, or 0.1%, to 1999, and the Nasdaq Composite Index shed four points, or 0.1%, to 4566.

Stocks retreated from record levels reached in Tuesday's quiet trading session, when the S&P 500 made its 30th record close for the year and the Dow hit a fresh intraday high.

There was little economic news on the calendar Wednesday, so traders instead eyed a regulatory filing from Chinese e-commerce giant Alibaba Group ahead of its initial public offering, which is expected next month. Yahoo Inc., which owns a chunk of the company, gained 0.5%.

"The Alibaba IPO is going to be enormous for Wall Street," said Michael Purves, chief global strategist for Greenwich, Conn.-based brokerage firm Weeden Co. Fund managers "may have to sell other stocks in the tech sector to make room for it."

Technology stocks lagged. Tech stocks led the S&P 500 index lower, shedding 0.3% in early trading.

The Dow has gained 3.2% and the S&P 500 is up 8.2% for the year, through Tuesday's close. The S&P 500 has recovered from a mid-July swoon, caused in part by a flare-up in concerns about Ukraine and the Middle East. The Dow isn't far behind, hovering 0.2% below its July 16 record as of Tuesday's close.

The latest advance has come amid light summer trading. That has pushed U.S. stock valuations further above long-term averages, which has left some strategists nervous that any unexpected bad news could prompt declines.

"People have to be prepared, if we continue to rally, when people get back to work [in September] you might get some volatility," said Mr. Purves.

Treasury prices continued to push higher, with the yield on the 10-year note remaining near its lowest level since June 2013. In recent trading, the yield on the benchmark 10-year note fell to 2.368%, according to FactSet.

European stocks were mixed, with the Stoxx Europe 600 edging up 0.1%. Expectations for further easing from the European Central Bank have been building in the wake of continued weak economic data and remarks from ECB President Mario Draghi last week.

In corporate news, Tiffany Co. rose 1.1% after it reported better-than-expected second-quarter results and lifted its earnings outlook for the year.

Burger King Worldwide Inc. is coming under criticism for its acquisition of Tim Hortons Inc. that would allow the hamburger chain to move its headquarters to Canada in a so-called tax inversion. Shares of Burger King fell 3.3% and shares of Tim Hortons shed 1.5%.

In commodity markets, crude-oil futures rose 0.1% to $94.00 a barrel. Gold futures slipped 0.2% to $1,282.80 an ounce.

Write to Alexandra Scaggs at alexandra.scaggs@wsj.com