(Bloomberg News) Less than halfway through the process of implementing the 2010 Dodd-Frank Act, the pace of rule-writing by the U.S. Securities and Exchange Commission has slowed by about half.

The agency's five commissioners haven't met once in the last four months to approve or propose regulations required under Dodd-Frank, designed to curb the kind of risky practices that fueled the 2008 financial crisis.

SEC Chairman Mary Schapiro acknowledged the slowdown, describing it as a "natural lull" after an initial gush of proposals.

"It's easier to propose rules than it is to adopt them," Schapiro told reporters in Washington last month, particularly after a court rejected one agency rule over its costs.

The rule-making holdup is extending a period of uncertainty for affected firms -- some welcome the delay of unwelcome regulations, others would prefer clarity.

Tom Quaadman, vice president of the U.S. Chamber of Commerce's Center for Capital Markets Competitiveness, described the law as imposing "impossible deadlines."

"They've given them a 2,400-page piece of legislation that really directs the regulators to do all the hard work," Quaadman said.

Among the rules in limbo are the so-called Volcker rule to ban banks' proprietary trading, restrictions on asset-backed securities deals, and forcing firms to disclose whether manufacturing metals were mined in war-ravaged parts of Africa.

Financial Revamp

Enacted in 2010, Dodd-Frank requires U.S. regulators to write hundreds of new rules to revamp how the financial sector does business, and more of those rules were assigned to the SEC than any other agency.

In the first year after the law's passage, the agency voted to approve 108 proposals, adoptions and rule concept releases, according to data compiled by Bloomberg, most of them related to Dodd-Frank. That's an average of nine per month.