A small band of humans is fighting what it warns is the rise of the machines in financial markets.

A group of two dozen brokers and traders has sued CME Group, the owner of major commodities exchanges in New York and Chicago, arguing that a new rule that took effect on Monday would benefit high-frequency traders, favoring machines over people and putting hundreds of jobs at risk at futures and options exchange the Chicago Board of Trade.

“A lot of people are going to lose their jobs,” said George Sang, the lead attorney for the plaintiffs in the suit. “High- frequency traders, computer programs will be displacing people out of their livelihoods.”

Under the current trading system, the final prices for futures contracts for everyday commodities like corn and soybean oil are negotiated in person, on the floor of the exchanges in an area known as the "pit." This "outcry market system," as it is known, is responsible for the noisy, frantic trading environment -- in which brokers and traders yell and hand-signal buy and sell orders with one another -- that many still associate with the floors of stock exchanges. Some of the customers that these traders and brokers work for are farmers looking to hedge the price of various crops.

The CME's new rule replaces this in-person trading process with a blended system that takes into account orders placed by computerized traders when arriving at a final settlement price for these contracts.

According to the lawsuit, this change "will, for all practical purposes, eliminate the open outcry pit based system."

"An emergency exists because if the proposed rule change is allowed to proceed on June 25, 2012, Plaintiffs and the overwhelming majority of other floor traders of the [Chicago Board of Trade] will lose the vast majority of their business almost immediately and will have to close their operations forever,” the lawsuit stated.

Sang represents 24 plaintiffs in the suit, though he said that hundreds more will be out of a job, such as those in the various positions supporting people working on the floor.

CME spokesman Chris Grams wrote in an email that the changes were meant to help the company abide by market regulations "as trading in our markets evolves." CME thinks trading under its new rule "accurately captures contract value ... and is fully consistent with our functions as a designated contract market and a derivatives clearing organization," Grams said.

Throughout the financial world, pit trading -- and the bustle that accompanies it -- is largely going the way of the buggy whip and is being replaced by a computerized system, much of it high speed, running silently, over servers.

As Bryan Harkins, chief operating officer of electronic stock exchange DirectEdge told The Huffington Post in April, "The floor of the New York Stock Exchange is basically a television studio right now” because much of the trading activity on that exchange has gone electronic.

Some see this transformation, including the loss of the traditional pit jobs, as part of a natural evolutionary process.

“Eventually electronic trading is going to dominate,” said Menachem Brenner, a professor of finance at New York University's Stern School of Business and a former floor trader. “The noisy pit is going to be history,” as will be the jobs there, he said. “They’re going to be obsolete.”

The plaintiffs in the CME lawsuit argue that the rule change they are fighting is part of a broader effort to cater to electronic trading and especially to high-frequency traders -- computerized trading firms that buy and sell stocks, bonds and derivatives by the millisecond or faster using computer algorithms. Market experts argue that many U.S. exchanges are increasingly reliant upon high-frequency trading outfits to provide trading volume.

In recent weeks, high-frequency trading has garnered attention from federal regulators, and the practice has been criticized for causing volatility in the markets, such as in 2010 when a freak flash crash caused the Dow Jones industrial average to lose 1,000 points in minutes.

Sang argued that the CME's rule change will being greater volatility to the commodities markets as well. “The market will be more manipulated than ever,” he said.