By Mike Bird

The Dow Jones Industrial Average pulled back from the elusive 20000 mark, after getting closer than ever on Friday.

The blue-chip index fell 28 points, or 0.1%, to 19936 on Monday. The S&P 500 declined 0.1%, and the Nasdaq Composite was up 0.2%.

The Dow industrials had risen to within one point of its next thousand-point milestone on Friday before retreating slightly. It was the best week for the Dow industrials since Dec. 9, while the S&P 500 and the Nasdaq Composite closed at fresh highs.

Many investors and analysts say they expect volatility to pick up in the coming months, when details about President-elect Donald Trump's prospective policies -- including tax cuts and fiscal stimulus -- become more clear. Some investors have dialed back on popular postelection trades in recent weeks.

"The stock market certainly seems to be embracing all the potential good news, but the devil is in the details," said Bill Costello, portfolio manager at Westwood Holdings Group. Mr. Costello added that he expects optimism to "wane and wax throughout the year" as investors learn of the extent to which Mr. Trump's much-talked-about policies can be implemented.

On Monday, energy stocks were among the worst performers in the S&P 500. Transocean, Range Resources and Southwestern Energy fell more than 3% each.

The decline in energy shares came as U.S. crude oil fell 2.9% to $52.45 a barrel. Analysts said some investors were growing increasingly concerned over rig counts, which have shown the number of rigs in the U.S. drilling for oil rising for 10 consecutive weeks, according to Houston-based oil-field services companyBaker Hughes.

Elsewhere Monday, the Stoxx Europe 600 declined 0.5%, with the banking and energy sectors -- which have helped power the recent rally in stocks -- losing more than 1% each.

The fall in stocks followed a sharp decline in the pound, which slumped to its lowest level since October against the dollar after U.K. Prime Minister Theresa May said Britain would make a definitive break from the European Union.

The government has promised that Article 50 -- which begins a two-year Brexit negotiation period -- will be triggered by the end of March.

The pound fell 1% against the U.S. dollar to $1.2168. The U.K.'s FTSE 100, which tends to benefit from a drop in sterling, was one of the few European indexes in positive territory, rising 0.4% to a fresh high.

In bond markets, the yield on the 10-year U.S. Treasury note fell to 2.383%, according to Tradeweb, from 2.417% Friday.

Earlier, Hong Kong's Hang Seng rose0.2% and the Shanghai Composite Index added 0.5%. Japanese markets were closed for a public holiday.

Akane Otani contributed to this article.

Write to Mike Bird at Mike.Bird@wsj.com

(END) Dow Jones Newswires

January 09, 2017 11:47 ET (16:47 GMT)

Copyright (c) 2017 Dow Jones & Company, Inc.