As financial institutions brace for legislative overhaul of their derivatives business, companies that enter into derivative contracts as part of a hedging strategy are wondering what the impending new regime will mean for them, too.

But thanks to a final burst of political intrigue in Washington last week that has plunged derivatives oversight back into uncertainty, right now nobody knows.

At issue is one section of the regulatory reform bill pending in Congress, which will require financial firms trading in derivatives to post more cash as collateral. Its intention is to prevent a major derivatives trader from going broke suddenly and leaving ...