Elizabeth Warren unveiled a policy proposal July 18 to slap new rules on private equity and “useless speculation” on Wall Street while rolling back President Donald Trump’s deregulation of the financial industry.

A centerpiece of her “economic patriotism” plan is to transform private equity firms, which she said often act like “vampires” when they buy companies by “bleeding the company dry and walking away enriched even as the company succumbs.”

Elizabeth Warren
Photographer: Sergio Flores/Bloomberg

The new plan from the former Harvard law professor highlights her unique populist pitch for the Democratic presidential nomination — a promise to meld her understanding of Wall Street...