Failed 2016 Democrat nominee Hillary Clinton issued a warning on Wednesday, asserting at the New York Times‘ DealBook conference that both Sen. Elizabeth Warren’s (D-MA) and Sen. Bernie Sanders’ (I-VT) plans to hike taxes on the ultra-wealthy would be “incredibly disruptive.”

Clinton appeared at the DealBook conference this week and dismissed both Warren’s and Sanders’ plans to tax the wealthy, suggesting their proposals are “complicated” and would not work in the long run.

“I just don’t understand how that could work, and I don’t see other examples anywhere else in the world where it has actually worked over a long period of time,” Clinton said.

Both Warren and Sanders have unveiled radical redistribution plans as key features of their presidential platforms. Warren’s “Ultra-Millionaire Tax” targets individuals with more than $50 million in assets, levying a two percent tax, which goes up to three percent for those with more than $1 billion in assets. However, her $52 trillion Medicare for All plan increases the taxes on the ultra-wealthy, “asking billionaires to pitch in six cents on each dollar of net worth above $1 billion.”

Sanders’ plan also targets America’s ultra-wealthy, proposing a one percent tax on couples with a net worth in excess of $32 million:

The tax rate would increase to 2 percent on net worth from $50 to $250 million, 3 percent from $250 to $500 million, 4 percent from $500 million to $1 billion, 5 percent from $1 to $2.5 billion, 6 percent from $2.5 to $5 billion, 7 percent from $5 to $10 billion, and 8 percent on wealth over $10 billion.

“Billionaires should not exist,” he declared following his plan’s rollout:

Clinton signaled that neither of their proposals is feasible.

“If you were going to do a wealth tax and it was on assets … how you would value it is, I think, complicated to start with,” she said.

“But assume you can get some system of evaluation, people would literally have to sell assets to pay the tax on the assets that they owned before the wealth tax was levied,” she continued.

“That would be incredibly disruptive, so I think there are other ways to raise the revenues,” she added.

Both Warren and Sanders took aim at billionaire Michael Bloomberg, who is close to making a decision on a presidential bid, following the reports that he filed presidential primary paperwork in Alabama ahead of the deadline.

“Welcome to the race, @MikeBloomberg! If you’re looking for policy plans that will make a huge difference for working people and which are very popular, start here,” Warren tweeted, providing a link to her calculator “for the billionaires.”

“The billionaire class is scared and they should be scared,” Sanders tweeted following the news.