Argument is simple enough: you would make trades unprofitable.

A proposal for Illinois to tax trades on exchanges in the state is “ridiculous,” according to the executive chairman of Chicago-based market operator CME Group Inc.

The suggested levy—which would charge $1 or $2 per contract, depending on the product—would make many transactions uneconomic, forcing the exchange to leave the state because customers would stop buying and selling, CME Chairman Terry Duffy said.

The bill, designed to increase revenue in the financially troubled state, is in early stages and faces long odds of approval.

Yes, as Sen. Don Harmon told an Oak Park audience in 2013, in this exchange from my Illinois Blues: How the Ruling Party Talks to Voters.

. . . from the floor came an enterprising suggestion, that even with Harmon’s proposed fair tax (“graduated”) there still wouldn’t be enough money. “So how about the proposed tax on stock trades?” (A “sales tax on speculators,” a columnist called it.)

[Rep. Camille Lilly] laughed. “Actually, I saw that proposal, among so many that I didn’t read.”

Harmon said he had heard testimony for this tax, naming a local socialist who was also an energetic proponent of a mandated “living wage” for village employees. But he gently poured cold water on the idea, Lilly next to him nodding vigorous agreement.

“There’s the fear that this legislation would push the Chicago Mercantile Exchange out of the state,” Harmon explained. It was a rare nod to the role of taxation in damaging the economy.

Illinois Blues is available also as paperback and non-Kindle ebook.

For the rest of the CME story: Newsalert: CME Boss says he would have no choice but to move CME if Illinois tax passes