A tweet from president-elect Donald Trump calling on the U.S. government to scrap an order with Boeing Co. for the development of a replacement for the Air Force One jet temporarily knocked about $1 billion US off the stock market value of the aircraft maker.

“Boeing is building a brand new 747 Air Force One for future presidents, but costs are out of control, more than $4 billion. Cancel order!” Trump tweeted Tuesday morning.

Boeing is building a brand new 747 Air Force One for future presidents, but costs are out of control, more than $4 billion. Cancel order!

“The plane is totally out of control. I think it’s ridiculous. I think Boeing is doing a little bit of a number. We want Boeing to make a lot of money but not that much money,” Trump later told reporters when he spoke in the lobby of the Trump Tower in New York.

Reuters reported that Boeing has not begun building the two replacement aircraft for the current Air Force One, and has not been awarded the money for them. The company is currently working on design and engineering for the aircraft.

“We are currently under contract for $170 million to help determine the capabilities of these complex military aircraft that serve the unique requirements of the president of the United States,” Boeing said in a statement.

The White House also said it didn’t know where Trump got his figure.

“Some of the statistics that have been cited, shall we say, don’t appear to reflect the nature of the financial arrangement  between Boeing and the Department of Defence,” White House  spokesman Josh Earnest told reporters.

The Government Accountability Office, the U.S. government’s auditing arm, in March 2016 estimated total program costs at more than $3.2 billion US between the 2010 and 2020 federal budget years.

According to the Associated Press, U.S. military officials say two new aircraft could cost at least $4 billion US for development, construction and future maintenance, matching the figure Trump cited. The officials were not authorized to comment publicly about the sensitive military project and spoke on condition of anonymity.

Boeing aircraft have been used to shuttle U.S. presidents since 1943. The new replacements for Air Force One are due to be in service by 2024.

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U.S. president-elect Donald Trump speaks to members of the news media in the main lobby at Trump Tower in Manhattan on Tuesday. (Brendan McDermid/Reuters)

Illustrating the power of Trump’s words, shares of Boeing opened sharply lower at the start of trading on the New York Stock Exchange on Tuesday. After finishing Monday at $152.16, the stock opened at $150.84 and got as low as $150.02, representing a drop in stock market value of about $1 billion US.

Following the initial shock, Boeing’s stock regained ground. It pushed into positive territory by early afternoon, climbing as high as $152.64.

In the wake of Trump’s tweet, the Washington Post later reported that a Trump spokesman said the president-elect had sold all of his shares in companies earlier this year. Jay Miller didn’t say why Trump had sold the shares or what he got for them.

Selling his stock portfolio could solve an issue for Trump: concerns that his holdings could present potential conflicts of interest.