Update (4/2/2018 10 am ET): With Amazon shares already heading lower thanks to Trump's weekend twitter thrashing, the president has again chimed in Monday morning, tripling down on his recent threatening rhetoric toward the e-commerce giant.

According to Trump, "only fools, or worse, are saying that our money losing Post Office makes money with Amazon. THEY LOSE A FORTUNE, and this will be changed."

Amazon shares were down more than 3.5% as the price of a single share slipped below the $1,400 level.

President Trump's obsession and escalating feud with Jeff Bezos, and bringing Amazon to heel before it destroys what's left of America's crumbling brick-and-mortar retail industry, was on display Saturday morning when he fired off a series of angry tweets claiming the Bezos-owned Washington Post should register as a lobbyist and that the Post Office should jack up its parcel rates to stick it to Amazon.