Amazon’s stock fell like a rock today, dropping more than 5% to close at $1,371.99, following a sustained Twitter assault from President Donald Trump.

Trump reignited his feud with Amazon during Holy Week, asserting that the U.S. Post Office subsidizes its delivery costs to the tune of $1.50 per package it delivers for the Seattle-based online retailer. He kept up the criticism of the retailing giant this morning, dragging down the company’s stock and the Dow Jones Industrial Average with it. The Dow tumbled 459 points to 23,644.19.

The barrage of presidential tweets throughout Easter Weekend, together with an Axios report last Wednesday that the president was “obsessed” with regulating the company, served to wipe out $50 billion in market capitalization.

Investors see Trump’s tweets, and Facebook’s Cambridge Analytica privacy debacle, as portending increased regulation and government involvement in the technology sector. That’s depressing the share prices of the high-performing tech stocks known by the acronym FANG: Facebook, Amazon, Netflix and Google.

“For investors in Facebook and Amazon these are two totally distinct regulatory issues which both have wide-ranging ramifications,” writes tech analyst Daniel Ives of GBH Insights. “Yet together, the confluence of these events has prove to be a significant worry for the Street around FANG names, sending a negative ripple effect across tech stocks.”

Amazon and The Washington Post are favorite Trump targets. During the 2016 presidential campaign, Trump once told a crowd of supporters, “If I become president, oh [does Amazon] have problems. They’re going to have such problems.”

Candidate Trump also accused Amazon CEO Jeff Bezos, who owns The Washington Post, of using the publication as lobbying tool, “so that the politicians in Washington don’t tax Amazon like they should be taxed.”

The president continues to revisit these themes, describing the newspaper in July as “Fake News Washington Post” and attacking Amazon, after the publication embarrassed the president in revealing that a fake Time magazine cover featuring Trump was hung in at least five Trump clubs around the world.

The latest round of attacks seems to have been ignited by the Axios story regarding Trump’s obsession with Amazon and its effects on American retail.

The New York Times examined Trump’s claims about the Postal Service’s losses, noting the nation’s mail service has been losing money since 2006, and the copious amounts of red ink can’t be attributed to Amazon alone.