Complex sentence: In 2007, SEC enforcement completed an investigation which began on January 6,2006, into a Ponzi scheme allegation which resulted in neither a finding of fraud, nor a referral to the SEC Commissioners for legal action.
Split into simpler sentences: In 2007, SEC enforcement completed an investigation they had begun on January 6,2006 into a Ponzi scheme allegation. This investigation resulted in neither a finding of fraud, nor a referral to the SEC Commissioners for legal action.