Wall Street is making headway in a campaign to persuade regulators to soften a key rule that has forced banks to boost capital since the financial crisis.

After financial firms complained for about a year that some of the new requirements will make it overly expensive to offer derivatives to clients, regulators planned to discuss possible concessions at a private meeting starting Wednesday, according to two people with knowledge of the talks. The meeting consists of policy advisers to a group of global authorities that includes the Federal Reserve, the European Central Bank (ECB), and the Bank of England, the people said.

The lobbying is tied to one aspect of how industry overseers set leverage ratios, which determine how much capital lenders need to offset their risks. As the rules are now written, banks take a hit on the billions of dollars in collateral they receive from customers for handling their derivatives trades.