U.S. regulators voted today to define which companies will face new oversight in the $708 trillion global swaps market, where largely unregulated trades helped fuel the 2008 financial crisis.

A rule approved unanimously by the Securities and Exchange Commission today and awaiting a Commodity Futures Trading Commission vote will initially define a regulated dealer as one that conducts swaps with a notional value of at least $8 billion in a 12-month period. The banks, hedge funds and energy firms defined as swap dealers will be subject to the highest capital and collateral requirements for market participants.

“Adopting these entity definitions is a foundational step in the establishment of the new regime to regulate trading in this very significant market,” SEC Chairman Mary Schapiro said before the vote. “These rules clarify for market participants whether their current activities will subject them to comprehensive oversight in the coming months.”