The head of Nasdaq OMX Group Inc said on Friday he does not expect any new obligations or privileges for U.S. “market-makers” until 2012 at the earliest, calling any regulatory change “a slippery slope.”

The U.S. Securities and Exchange Commission, reacting to the May “flash crash,” has suggested it might be necessary to saddle some high-frequency trading firms with obligations to make markets and add liquidity during stressful times.

“I don’t think something will happen in 2011,” Nasdaq OMX Chief Executive Officer Robert Greifeld said on a conference call, adding it would be “a difficult road to try to properly define what responsibility and privileges to give participants.”