The trillions of dollars of trades that zip through the data centers scattered across northern New Jersey usually do so quietly. At least, until the state wants a slice.

The biggest U.S. stock exchanges and major market-makers are joining forces to fight a proposed tax on financial transactions under consideration by New Jersey Governor Phil Murphy. Members of the newly formed coalition -- such as New York Stock Exchange, Nasdaq Inc., Citadel Securities and Virtu Financial Inc. -- are threatening to move operations out of the state if the tax is enacted.

Now, an industry test of backup systems later this month is turning into a showcase that Wall Street firms can pack their bags if needed. Modern markets are built on speed, but the biggest companies say they’ll sacrifice a few fractions of a second if it means avoiding billions in taxes.

“On Sept. 26, we will conduct a test to ensure that the industry is prepared for a move out of New Jersey should the tax pass,” the coalition, which calls itself the Coalition to Prevent the Taxing of Retirement Savings, said in a statement Friday.

Murphy said on Aug. 31 he was “very seriously” considering a tax on high-volume electronic trading in the state, home to Wall Street’s massive server farms. The state would charge a quarter of a cent per “financial transaction” at entities processing at least 10,000 annually via electronic infrastructure, according to a recently introduced bill.

The state could collect $10 billion annually from the tax on stocks, options, futures and swaps trading via New Jersey electronic data centers, according to its Democratic sponsor, Assemblyman John McKeon. Murphy, a Democrat and retired Goldman Sachs Group Inc. senior director, favors using the revenue to expand his social-justice agenda and shore up the state’s fiscal health, according to senior administration officials.

State finances have been slammed by the Covid-19 pandemic, and New Jersey, one of the most indebted U.S. states, has unfunded pension and benefits obligations of well over $200 billion.

The finance industry has long been quick to fight the profit threat from transaction taxes, including one floated by Senator Bernie Sanders last year in his presidential campaign. An International Monetary Fund study in 2011 suggested that transaction taxes initially target the finance industry, but eventually firms pass on higher costs to customers.

New Jersey’s proposed levy “would hurt the tens of millions of Americans who invest in financial markets to save for retirement and fund their children’s education,” the industry coalition said Friday. “Our members are committed to ensuring that those savers continue to have access to the lowest cost and most efficient markets in the world.”

NYSE said earlier Friday it would operate its Chicago equity exchange from a secondary data center from Sept. 28 to Oct. 2 to “confirm the industry’s ability to seamlessly move live trading out of New Jersey.”

Nasdaq said the Sept. 26 test will simulate a normal trading day, with its Chicago data center acting as the primary location for its equities and options matching engines. In notices to clients, both Nasdaq and Cboe emphasized the importance of the test to ensure markets were ready to relocate.

UBS Group AG, Cboe Global Markets Inc., Members Exchange, and TD Ameritrade Holding Corp. are part of the coalition. Equinix Inc., which runs data centers in New Jersey that underpin the world’s biggest and most active stock markets, also joined the group.