A number of celebrity Under Armour endorsers - including basketball star Stephen Curry and ballerina Misty Copeland - released statements saying they did not agree with Plank's assessment.
When Merck CEO Kenneth Frazier became the first member of President Donald Trump's American Manufacturing Council to resign in the wake of the president's equivocal response to the weekend's violent Unite the Right rally in Charlottesville, Va., he stood alone among his fellow titans of industry.
But he later lashed out again at Frazier, showing he had more anger toward a leading African-American executive who shamed him than he had for a domestic terrorist who killed an innocent woman who was protesting white supremacy.
Like several other corporate leaders, Alex Gorsky, chairman and CEO of Johnson & Johnson, said that intolerance and racism have no place in USA society but that he meant to stay on the manufacturing council.
"JOBS!" Trump tweeted, moments before Paul announced his decision. "With more than 100,000 employees in the United States", a GE spokeswoman said, "it is important for GE to participate in the discussion on how to drive growth and productivity in the USA, therefore, Jeff Immelt will remain on the Presidential Committee on American Manufacturing while he is the chairman of GE".
Just months ago, Plank found himself at the center of controversy for comments that showed support for President Trump.
"I resigned to call attention to the serious harm our divided political climate is causing to critical issues, including the serious need to address the decline of American manufacturing", said Intel's Brian Krzanich. He notes that many chiefs are privately outraged, but too scared to say anything publicly that could position them or their business as targets to the president's ire.
"Following yesterday's remarks from the president, I can not remain on the Manufacturing Jobs Initiative", Morrison said in a statement.
On Monday afternoon, Trump belatedly blamed white supremacist groups by name for the Charlottesville violence that led to three deaths, a delayed response that did little to assuage critics.
CEOs have dropped out of President Trump's councils before over disagreements.
So who has left the council and what were their reasons for doing so?
Ever since Trump assumed office, executives have struggled to balance their desire to engage the White House on policy with the growing expectations by some that they exercise a voice on social issues - all at the risk of alienating shareholders and customers on one side or another.
Over 26,000 people have signed a petition by consumer watchdog group SumofUs, demanding CEOs on President Trump's business councils to resign from their posts advising the president.
At an early meeting with pharmaceutical companies, Frazier sat at Trump's side.
Unfortunately for Merck shareholders, Frazier's high profile exit might backfire, because Trump fired back about high drug prices shortly following the CEO's decision.