More than a dozen Wall Street trading firms systematically cheated their customers of millions of dollars by improperly slicing bits of profit from countless trades, federal regulators said on Wednesday.

The Securities and Exchange Commission disclosed the allegations after negotiating settlements. The firms did not admit or deny the charges but agreed to pay a total of more than $69 million in forfeited profits and penalties.

The 14 firms named in the complaints are all “specialists,” trading firms that have a specific duty to maintain orderly markets by matching buyers and sellers and standing ready to conduct trades when buyers or sellers are scarce. They include units or subsidiaries of well-known Wall Street names, including E*Trade Capital Markets, Goldman Sachs Execution and Clearing, Knight Financial Products and TD Options.

Regulators said the firms had engaged in various types of “front-running,” which involves trading ahead of customer orders or timing their own trades to seize profits. For instance, specialists that had a big order to buy a stock would first buy it from a seller themselves and then illegally bid up the price moments before selling it to profit on the transaction.