Credit Suisse and Barclays are in discussions to pay as much as $150 million combined to end several investigations and one lawsuit alleging improprieties related to their “dark pools,” according to people familiar with the matter.

The settlement talks with the Securities and Exchange Commission and New York Attorney General could result in the two biggest penalties to date for alleged wrongdoing at bank-operated private-trading venues. The biggest thus far is the $20.3 million New York brokerage Investment Technology Group agreed to pay the SEC in August. ITG admitted wrongdoing in its case.