NEW YORK —  The closely watched Dow Jones industrial average topped 25,000 points for the first time Thursday, continuing a run that lifted stocks by more than 20 percent in 2017.

The bellwether gauge crossed the historic milestone shortly after the start of the day’s trading. The latest surge comes as Wall Street analysts raise their forecasts for a wide variety of companies, betting they will benefit from the strength of the global economy and a move by Congress to cut business taxes. Technology and energy companies led the charge this week, the latter as anti-government protests in Iran sparked fears of oil disruptions and brutally cold weather fed demand for heating fuel. Asian and European stock markets were all up overnight as well, and a positive holiday sales report from retailer J.C. Penney Thursday morning boosted shares further.

For the Dow, encompassing 30 large publicly traded companies, reaching the 25,000 milestone holds more symbolic than practical value. It has risen steadily since 2009, but has marked 2017 by repeatedly marching through record levels. The Dow passed the 20,000 threshold days after Trump took office then kept climbing, posting 71 record highs last year. It passed 24,000 on Nov. 30, making the latest 1,000-point run one of the fastest in its history.

In 2017, the broader Standard & Poor’s 500-stock index and the tech-heavy Nasdaq composite index also posted their best years since 2013, and they have continued to climb this year.

The steady rise in U.S. markets has befuddled some veteran traders who say it can’t be explained by the traditional metrics used to value stock prices. The S & P 500 hasn’t dipped 3 percent in more than a year for the first time in recent history. Some investors appear to be ignoring the normal warning signals for fear that they could miss out on more profits if they sell now, market analysts said.

Those signs include rising U.S. tensions with North Korea, an economic slowdown in China, the fallout from Britain’s decision to leave the European Union and even a special prosecutor investigation into Russian meddling into the 2016 election have failed to shake markets. Stocks have continued to climb even as the Trump administration threatens to renegotiate trade deals that could spark retaliation by giants like China.

Some market analysts say, when stock prices inevitably begin to fall, the decline could be more dramatic and quicker than it has in the past. If the tax bill does not generate the kind of economic growth Republicans expect, for example, it could prompt investors to cash in their profits. Investors have, so far, also have ignored the potential market volatility that could coincide with Federal Reserve Chair Janet Yellen stepping down next year, they say.

An eventual correction could “take some of the froth out of the market,” said Mark Stoeckle, chief executive of Adams Funds. “That could be a good thing for a long-term investor.”