WASHINGTON — President Trump once again lashed out at Amazon.com, the online retailing giant, on Thursday morning, saying he has long had concerns about the company’s business practices.

“I have stated my concerns with Amazon long before the Election. Unlike others, they pay little or no taxes to state & local governments, use our Postal System as their Delivery Boy (causing tremendous loss to the U.S.), and are putting many thousands of retailers out of business!,” he tweeted.

Trump has periodically criticized Amazon before and since becoming president. Jeff Bezos, the founder and chief executive of Amazon, also owns The Washington Post.

Trump’s latest critique comes after Amazon’s stock took a hit Wednesday following the publication of a report in Axios that Trump was “obsessed” with the retail giant, according to a person interviewed by the publication. Shares fell more than 4 percent on Wednesday, and continued their tumble Thursday, falling more than 3.8 percent in morning trading.

Some of Trump’s claims about Amazon have not been based on complete information. Amazon, for example, does collect taxes on products it sells to customers in the 45 states with a sales tax. Items sold by third-party vendors, however, may have different arrangements. The company has also said it supports legislation that would require other online retailers to pay state and local sales taxes.

Amazon declined to comment on Trump’s tweet Thursday.

Trump’s use of social media to call out individual people and companies has been unprecedented for a president. His other Twitter targets have included Apple, Boeing and General Motors, as well as media outlets including The Washington Post, The New York Times and CNN.

The president has long been vocal with his disapproval of Amazon. In December, Trump attacked the company’s arrangement with the U.S. Postal Service and called on the agency to raise the shipping rates it charges Amazon.

“Why is the United States Post Office, which is losing many billions of dollars a year, while charging Amazon and others so little to deliver their packages, making Amazon richer and the Post Office dumber and poorer?,” he tweeted. “Should be charging MUCH MORE!”

His tweets about the USPS reflect a debate about whether the Postal Service is charging Amazon and other retailers enough to deliver packages. Parcel delivery has become an increasingly important part of the Postal Service’s business as first-class mail has been on a long-running decline.

Earlier in his presidency, Trump tweeted that “Amazon is doing great damage to tax paying retailers. Towns, cities and states throughout the U.S. are being hurt – many jobs being lost!”

He has also suggested that The Post is “a lobbyist weapon against Congress to keep Politicians from looking into Amazon no-tax monopoly.”

The Post’s editors and Bezos have declared that Bezos is not involved in any journalistic decisions. The Post is owned by Bezos personally, not by Amazon.