Defense attorney Joseph Tacopina said Leszczynski was "astonished and shocked he was charged with a crime. He still doesn't know why."
Guy Oksenhendler, an attorney for Chouchane, declined to comment.
In a release, the Securities and Exchange Commission also announced civil charges against the men, saying their markups and markdowns of prices they reported to their customers ranged from a few dollars to $228,000 in more than 36,000 transactions over the four-year period. The SEC said some of the fees were more than 1,000 percent of what they were telling their customers they were being charged.
"These brokers stole millions of dollars by overcharging customers for trades involving stocks with high trading volumes and price volatility, which are characteristics they wrongly thought would conceal their illicit pricing scheme," said Robert Khuzami, director of the SEC's Division of Enforcement. "They underestimated the SEC's ability and resolve to pursue such illegal schemes."