Trump promises a major tax announcement in a few weeks

President Donald Trump, facing doubts about the speed of his promised tax reform, said Thursday he will announce a plan in a few weeks.

In a meeting with U.S. airline executives, Trump spoke again on removing regulations for American businesses.

"Lowering the overall tax burden on American business is big league ... that's coming along very well. We're way ahead of schedule, I believe. And we're going to announce something I would say over the next two or three weeks that will be phenomenal in terms of tax," Trump said.

In a press briefing on Thursday, White House spokesman Sean Spicer told reporters that Trump realizes middle-class Americans need tax relief and that the U.S. needs "fundamental comprehensive tax reform."

The president also wants to create a tax plan that keeps jobs here, and incentivize companies to grow and come here, Spicer said.

Stocks and Treasury yields had jumped in the wake of Trump's Nov. 8 victory, amid the prospects for looser regulations in certain sectors, lower tax rates and fiscal stimulus.

However, investors appeared to be worried about delays after complications surrounding Republican attempts to repeal and replace Obamacare.

In a Fox News interview that aired Sunday night, Trump said a replacement for Obamacare might not be ready until next year.

"You have to remember Obamacare doesn't work, so we are putting in a wonderful plan," Trump told Fox News' Bill O'Reilly.

After Trump's comments on Thursday, the 10-year Treasury yield moved up slightly. The dollar also jumped on Trump's announcement. The S&P moved about 4 points.

"That added to the bearish price action that was already in place. It was more contributing to the negative tone that was in place. His comments were worth about two basis points," said Ian Lyngen, head of U.S. rates strategy at BMO.

"People were talking about it," he said, but added that it provided no detail and therefore not much clarity for the markets.

Trump meets US airline executives

Trump met on Thursday with U.S. aviation executives to discuss the industry's aging airports and air traffic control reform. Trump said the current government contract for a new air traffic control system is not good and is "obsolete."

Trump said the head of the Federal Aviation Administration should be a pilot.

The White House meeting came at a time of heightened tension within the industry after U.S. carriers raised concerns about ongoing trade agreements with foreign carriers. Trump has vowed to renegotiate or scrap trade deals he sees as unfair between the United States and other countries.

The Trump administration had not yet addressed the U.S. carriers' competition concerns.

Following the meeting, Delta Air Lines CEO Ed Bastian said the company plans to hire 25,000 people over the next five years with the support of "a level playing field globally."

"We had a positive discussion about many of the major issues facing U.S. travelers, airline employees and the aviation industry, which is a vital economic engine for America. I look forward to working with President Trump, Secretary Chao, Secretary Tillerson and other members of the administration on issues important to Delta, our employees and our customers," Bastian said in a statement.

United Airlines CEO Oscar Munoz said the company was committed to protecting and creating American jobs.

"We look forward to working together with the president on the many initiatives and issues that will make America better and the U.S. aviation industry the best in the world. This includes modernizing our aviation infrastructure and cutting the red tape that gets in the way of our industry's ability to deliver the best experience for our employees and customers," he said.

Jetblue and Alaska Airlines also released statements, saying they had positive meetings with the president.

—CNBC's Patti Domm and Reuters contributed to this report.