More than 200 companies chose Cyber Monday — traditionally the largest online sales days of the year — to call on the Federal Communications Commission to preserve the open internet.

Firms including Twitter, Tumblr, Square and Reddit noted that that Americans spent almost $3.5 billion last year in an one-day online shopping binge made possible by the free and open internet. These companies said the internet is an open marketplace where all businesses — from established players to an aspiring fashion designer in Wyoming — can thrive and compete equally.

The companies, in a letter to FCC Chairman Ajit Pai, said his proposal to repeal net neutrality rules that require Internet service providers treat all traffic equally threaten to “end this open commerce.”

“Without these rules, internet service providers will be able to favor certain websites and e-businesses, or the platforms they use to garner new customers, over others by putting the ones that can pay in fast lanes and slowing down or even blocking others,” the group wrote. “Businesses may have to pay a toll just to reach customers. This would put small and medium-sized businesses at a disadvantage and prevent innovative ones from getting off the ground.”

Pai said he wants the FCC to stop “micromanaging” the Internet, and return to the state of play before the government chose to regulate service providers like utilities.

Broadband for America, a coalition whose members include such giant broadband providers as AT&T and Comcast and trade groups including the Telecommunications Industry Association and USTelecom Association — issued a statement this morning, applauding the proposed change. These groups argued deregulation would lead to renewed investment and innovation, after a two-year decline in capital spending.

“We are also proud to reaffirm our unshakeable commitment to an open internet. This means no blocking of legal content, no throttling, no unfair discrimination, and continued transparency in our customer practices,” the group said in a statement today. “We stand by an open internet because it’s good for our business, and our customers expect and deserve it.”

The FCC plans to vote on the new rules, called the Restoring Internet Freedom Order, at its December 14 open meeting.