The Dow Jones Industrial Average set a sixth-straight record Wednesday, closing above 22,000 for the first time, but experts point out that whatever goes up must always come down.
The Dow closed up a fraction at 22,016.
Healthy earnings reports from computer technology giant Apple, the world's largest publicly traded company, and airplane manufacturer Boeing were major contributors to the Dow hitting another major milestone.
The Dow Jones is an index of 30 major companies from a variety retail, manufacturing and service industries. It has been used as a gauge of the health of the U.S. stock market for more than 100 years.
The Dow is up 11 percent so far this year and all of Wall Street has been in what is known as a "bull market" for several years.
It has been buoyed, in part, by better-than-expected corporate earnings and expectations brought on by the pro-business Trump White House.
But some analysts say they cannot see a lot of room for the Dow to go much higher.
They say that while they expect more positive earnings reports, Congress' inaction on President Trump's proposed tax cuts could take some wind out of investor optimism.
Plus, they point out that the Dow Jones Industrial Average is an index of just 30 companies, which they say is sometimes a narrow gauge of overall investor confidence.
Some other world markets have outperformed the New York Stock Exchange so far this year, such as the Dow Jones China 88 Index, the eurozone's Euro Stoxx Index and the Sao Paulo Bovespa Index in Brazil.