The Dow Jones industrial average saw its best one-day point gain since the day before President Donald Trump was elected, and closed at an all-time high Wednesday as the stock market continues to reflect economic optimism in the Trump era, USA Today reports.

The numbers

The Dow rose 322.79 points (1.3%), the best one-day gain in 14 months.

It closed at 26,115.65, the first time the Dow has broken the 26,000 mark in its 121-year history.

Just 13 days ago, the Dow rose above 25,000, which makes this the fastest 1,000-point climb ever.

What’s causing the rise?

The new GOP tax law may be contributing heavily to the sharp rise.

Wall Street analysts have been boosting 2018 earnings forecasts for U.S. companies at a very fast pace since Trump signed the tax bill into law. Those projections are boosting the stock market.

Is there a downside?

Maybe. Some skeptics believe that the record-breaking rise of the Dow could lead to a painful fall back to earth.

“There is a danger that the U.S. stock market could accelerate so quickly that it decouples from the economic fundamentals most analysts think currently underpin it,” said Jacob Deppe, head of trading at Infinox. “The fear is the higher stocks climb now, the further they may have to fall later.”