President Donald Trump and Amazon CEO Jeff Bezos

President Donald Trump accused Amazon on Thursday of not paying enough tax, taking advantage of the US postal system and putting small retailers out of business, but he offered no evidence to back up his criticisms and did not suggest any actions he would take.

Trump has attacked Amazon and its Chief Executive Jeff Bezos several times, and his latest comment came a day after news website Axios reported he was obsessed with the world’s largest online retailer and wanted to rein in its growing power, possibly with federal antitrust or competition laws.

“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!” Trump tweeted early on Thursday.

Amazon shares fell as much as 4.5 percent in morning trade, but recovered and closed up just over 1 percent. The stock dropped 5 percent on Wednesday following the Axios report. Amazon declined to comment on the tweet.

The retailer and cloud computing pioneer is the latest company Trump has singled out for praise or condemnation, although the effect on stock prices of his targets is generally short-lived.

Trump’s criticism did not diminish US fund managers’ long-term enthusiasm for Amazon, whose stock has risen more than five-fold in the last five years.